machine

package
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 Go to latest Published: Apr 12, 2026 License: Apache-2.0 Imports: 18 Imported by: 0

Documentation

Overview

ADDING A NEW PROMOTED OP

Promoted ops inline hot primitives directly in the VM dispatch loop, bypassing arity check, arg binding, and indirect function call. Each promoted op has a non-tail and tail variant.

The 34 switch cases in Run() are deliberately hand-unrolled: Go compiles them to a jump table. A table-driven approach was benchmarked and rejected (~1.5% geo mean regression). See plans/2026-04-05-structural-reduction.md.

Edit sites (3 files):

  1. opcode.go — add OpXxx + OpXxxTail constants; add two opcodeTable entries with operandKind: OperandCachedBinding
  2. machine_context.go — add two case branches in Run() (non-tail + tail), each calling execPromoted(mc, instr, name, arity, tail, inlineFn)
  3. call_promoted.go — implement inlineXxx function; add case in promotedOpForName() (or call_promoted_arithmetic.go for numeric ops)

No changes needed in native_template.go or disassemble.go — both use opcodeTable[op].operandKind metadata to handle OperandCachedBinding generically. The peephole optimizer (peephole.go) also needs no changes — it uses promotedOpForName() to discover promoted ops generically.

Package machine implements the Scheme virtual machine, compiler, and macro expander.

The machine package is the core execution engine for Wile, providing:

Compilation Pipeline

Scheme source undergoes three phases:

  1. Expansion: macro-expand via [ExpanderTimeContinuation]
  2. Compilation: generate bytecode via [CompileTimeContinuation]
  3. Execution: run bytecode via MachineContext

Virtual Machine

The VM is a stack-based bytecode virtual machine with:

Continuations

Macro System

Implements R7RS hygienic macros with Flatt's "sets of scopes" model:

  • [ExpanderTimeContinuation]: macro expansion driver
  • syntax-rules pattern matching via internal/match
  • syntax-case with fenders and procedural macros

Foreign Functions

Go functions are exposed as ForeignFunction implementations: 

type ForeignFunction func(CallContext) error

CallContext is the narrow interface (7 methods) that extensions depend on. The ForeignClosure type wraps these for the VM.

Index

Constants

This section is empty.

Variables

View Source 
var DefaultPromptTag = NewPromptTag("default")

DefaultPromptTag is the default prompt tag installed at the top of execution.

View Source 
var ErrBindingNotFound = werr.NewStaticError("binding not found")
View Source 
var ErrInvalidGlobalIndex = werr.NewStaticError("literal is not a global index")
View Source 
var ErrInvalidLiteralIndex = werr.NewStaticError("invalid literal index")
View Source 
var ErrInvalidProgramCounter = werr.NewStaticError("invalid program counter")
View Source 
var ErrLocalIndexOverflow = werr.NewStaticError("local index overflow")

ErrLocalIndexOverflow signals that a De Bruijn index slot or depth exceeds the int16 encoding range (-32768..32767). EncodeLocalIndex panics with this sentinel when the bytecode format cannot represent the index.

View Source 
var ErrMachineDoNotAdvancePC = werr.NewStaticError("machine do not advance PC: operation did not advance program counter")

Functions

func DecodeLocalIndex added in v1.4.0 

func DecodeLocalIndex(arg int32) (slot, depth int)

DecodeLocalIndex unpacks slot and depth from a bit-packed Instruction.Arg.

func DisassembleString added in v1.10.5 

func DisassembleString(tpl *NativeTemplate) string

DisassembleString produces a columnar human-readable listing from a NativeTemplate.

func EncodeLocalIndex added in v1.4.0 

func EncodeLocalIndex(li *environment.LocalIndex) int32

EncodeLocalIndex packs a LocalIndex's slot and depth into a single int32 for storage in Instruction.Arg. Slot occupies the low 16 bits; depth occupies the high 16 bits. Both values must fit in int16 range (max 32767).

De Bruijn indices (de Bruijn 1972). Variables are addressed by numeric coordinates, eliminating name lookup at runtime. 

addr(x) = (slot, depth), where:
  depth = number of enclosing λ-binders from use to definition
  slot  = index within the binding array at that depth

Encoding: Arg = (depth << 16) | (slot & 0xFFFF)

Invariant: the same variable always has the same (slot, depth)
  regardless of its name. Alpha-equivalence is a non-issue at runtime.
Constrains: GetLocalBindingBySlotDepth / SetLocalValueBySlotDepth
  (runtime access walks depth parent pointers, indexes by slot),
  linked closures (parent chain must match compile-time depth).
Constrained by: resolveLocal (compile-time computation of depth
  by walking the EnvironmentFrame parent chain).

See BIBLIOGRAPHY.md "De Bruijn Indices / Lexical Addressing".

func FindCommonWindingPrefix 

func FindCommonWindingPrefix(current, target WindingStack) int

FindCommonWindingPrefix finds the longest common prefix of two winding stacks. Returns the index where they diverge (0 means no common frames).

func GraftContinuation 

func GraftContinuation(segment, target *MachineContinuation)

GraftContinuation walks the segment chain to its bottom frame and sets its parent to target, effectively splicing the segment onto the target chain.

func ReleaseSubContext added in v1.4.0 

func ReleaseSubContext(mc *MachineContext)

ReleaseSubContext zeros the MachineContext and returns it to the pool. Exported because call sites live in other packages (registry/, extensions/).

func ReleaseTopLevelContext added in v1.5.0 

func ReleaseTopLevelContext(mc *MachineContext)

ReleaseTopLevelContext zeros the MachineContext and returns it to the pool. Exported because the primary call sites live in the root wile package (engine.go).

Types

type BarrierToken added in v1.4.0 

type BarrierToken struct {
	// contains filtered or unexported fields
}

BarrierToken is an opaque identity for a with-continuation-barrier scope. Each call to call-with-continuation-barrier creates a fresh token. Barrier crossing is detected by pointer identity comparison: if the capture-time token differs from the invocation-time token, the continuation would cross a barrier boundary.

nil means "not inside any barrier."

The _ field ensures non-zero struct size. Go may return the same pointer for all zero-sized allocations (runtime.zerobase), which would defeat pointer identity comparison.

func NewBarrierToken added in v1.4.0 

func NewBarrierToken() *BarrierToken

NewBarrierToken creates a fresh barrier identity token.

type Breakpoint 

type Breakpoint struct {
	ID       BreakpointID
	File     string
	Line     int
	Column   int // 0 = any column on line
	Enabled  bool
	HitCount int
}

Breakpoint represents a source-level breakpoint.

type BreakpointID 

type BreakpointID int

BreakpointID uniquely identifies a breakpoint.

type CallContext added in v1.10.7 

type CallContext interface {
	// Arg returns the argument at the given positional index.
	// For variadic functions, the last parameter index holds the rest list.
	Arg(index int) values.Value

	// SetValue sets the single return value.
	SetValue(v values.Value)

	// SetValues sets multiple return values for R7RS values/call-with-values.
	SetValues(vs ...values.Value)

	// Authorizer returns the security authorizer for permission checks.
	Authorizer() security.Authorizer

	// Context returns the Go context for cancellation and timeout.
	Context() context.Context

	// EnvironmentFrame returns the current lexical environment frame.
	EnvironmentFrame() *environment.EnvironmentFrame

	// Thread returns the SRFI-18 thread object (nil for primordial thread).
	Thread() *values.Thread
}

type CapturedContinuation added in v1.7.0 

type CapturedContinuation struct {
	// contains filtered or unexported fields
}

CapturedContinuation is the value returned by call/cc to Scheme code. It is both callable (invoking it escapes to the captured point) and introspectable (continuation-marks can extract marks from its chain).

This replaces the opaque ForeignClosure that call/cc previously returned. The escape logic (thread check, barrier check, compose-then-abort) now lives in applyCapturedContinuation rather than inside a Go closure.

func NewCapturedContinuation added in v1.7.0 

func NewCapturedContinuation(
	cc *ComposableContinuation,
	threadID uint64,
	barrierValid *BarrierToken,
) *CapturedContinuation

NewCapturedContinuation creates a captured continuation value from a composable continuation segment and the safety context at capture time.

func (*CapturedContinuation) AcceptsArity added in v1.7.0 

func (p *CapturedContinuation) AcceptsArity(n int) bool

AcceptsArity reports whether this continuation can be called with n arguments. Escape continuations accept exactly 1 argument — the value to resume with.

func (*CapturedContinuation) ComposableContinuation added in v1.7.0 

func (p *CapturedContinuation) ComposableContinuation() *ComposableContinuation

ComposableContinuation returns the underlying composable continuation, which carries the MachineContinuation chain for mark extraction.

func (*CapturedContinuation) EqualTo added in v1.7.0 

func (p *CapturedContinuation) EqualTo(o values.Value) bool

func (*CapturedContinuation) IsVoid added in v1.7.0 

func (p *CapturedContinuation) IsVoid() bool

func (*CapturedContinuation) SchemeString added in v1.7.0 

func (p *CapturedContinuation) SchemeString() string

type CaseLambdaClosure 

type CaseLambdaClosure struct {
	// contains filtered or unexported fields
}

CaseLambdaClosure dispatches to the first clause whose arity matches the argument count. Each clause is a MachineClosure with its own template and captured environment.

func NewCaseLambdaClosure 

func NewCaseLambdaClosure(closures []*MachineClosure) *CaseLambdaClosure

func (*CaseLambdaClosure) AcceptsArity added in v1.5.0 

func (p *CaseLambdaClosure) AcceptsArity(n int) bool

AcceptsArity reports whether any clause in this case-lambda can accept n arguments.

func (*CaseLambdaClosure) Clauses 

func (p *CaseLambdaClosure) Clauses() []*MachineClosure

func (*CaseLambdaClosure) Doc added in v1.10.7 

func (p *CaseLambdaClosure) Doc() string

Doc returns the documentation from the first clause's template, or "" if no clauses.

func (*CaseLambdaClosure) EqualTo 

func (p *CaseLambdaClosure) EqualTo(o values.Value) bool

EqualTo implements Scheme equality for case-lambda closures. Two void closures (nil receivers) are considered equal to each other. Non-void closures are equal only if they have the same number of clauses and each corresponding clause is EqualTo its counterpart.

func (*CaseLambdaClosure) FindMatchingClause 

func (p *CaseLambdaClosure) FindMatchingClause(argCount int) (*MachineClosure, bool)

FindMatchingClause finds the first clause that matches the given argument count. It returns the matching closure and true when a clause can accept exactly argCount arguments (for fixed-arity clauses) or at least argCount arguments (for variadic clauses). If the receiver is nil or no clause matches, it returns nil, false.

func (*CaseLambdaClosure) IsVoid 

func (p *CaseLambdaClosure) IsVoid() bool

IsVoid reports whether this value represents the absence of a case-lambda closure. A nil receiver is treated as a distinguished "void" closure value, used as a sentinel to mean "no closure" rather than an error.

func (*CaseLambdaClosure) Name added in v1.10.7 

func (p *CaseLambdaClosure) Name() string

Name returns the name from the first clause's template, or "" if no clauses.

func (*CaseLambdaClosure) SchemeString 

func (p *CaseLambdaClosure) SchemeString() string

SchemeString returns the Scheme-readable representation of a case-lambda closure. Note that the void value (nil receiver) still prints as a case-lambda closure; callers must use IsVoid to distinguish the sentinel.

type ClausesWrapper added in v1.10.5 

type ClausesWrapper struct {
	Clauses []*SyntaxRulesClause
}

ClausesWrapper wraps a slice of SyntaxRulesClause as a values.Value for storage in NativeTemplate literals.

func (*ClausesWrapper) EqualTo added in v1.10.5 

func (p *ClausesWrapper) EqualTo(other values.Value) bool

func (*ClausesWrapper) IsVoid added in v1.10.5 

func (p *ClausesWrapper) IsVoid() bool

func (*ClausesWrapper) SchemeString added in v1.10.5 

func (p *ClausesWrapper) SchemeString() string

type Closure added in v1.5.0 

type Closure interface {
	values.Callable
	NamedCallable
	// contains filtered or unexported methods
}

Closure is a callable that can be directly applied — either a compiled Scheme closure (*MachineClosure) or a Go foreign function (*ForeignClosure). Distinguished from other Callable types (CaseLambdaClosure, Parameter, ComposableContinuation) which have different application semantics.

type ComposableContinuation 

type ComposableContinuation struct {
	// contains filtered or unexported fields
}

ComposableContinuation is a callable value wrapping a delimited continuation segment (a chain of MachineContinuation frames) plus the captured winding stack. When applied, it splices its frames onto the current continuation, effectively composing the captured computation with the current one.

This implements Racket-style composable continuations as described in Flatt, Yu, Findler, Felleisen "Adding Delimited and Composable Control to a Production Programming Environment" (ICFP 2007).

func NewComposableContinuation 

func NewComposableContinuation(cont *MachineContinuation, windingStack WindingStack, threadID uint64, barrierValid *BarrierToken) *ComposableContinuation

NewComposableContinuation creates a composable continuation from a continuation chain segment and the winding stack captured at the point of capture. barrierValid is mc.BarrierValid() at capture time; nil means the capture happened outside any with-continuation-barrier.

func (*ComposableContinuation) AcceptsArity added in v1.5.0 

func (p *ComposableContinuation) AcceptsArity(n int) bool

AcceptsArity reports whether this composable continuation can be called with n arguments. Composable continuations accept exactly 1 argument — the value to resume with.

func (*ComposableContinuation) AcquireSegment added in v1.6.0 

func (p *ComposableContinuation) AcquireSegment() *MachineContinuation

AcquireSegment returns the continuation segment for grafting.

First invocation marks the segment shared and returns it directly, avoiding a DeepCopy. Shared marking ensures RestoreAndRelease preserves frame evals for potential re-invocation.

Subsequent invocations reset the bottom frame's parent to nil (undoing GraftContinuation's mutation from the prior invocation) and deep-copy from the preserved shared frames.

This optimizes one-shot continuations (the common case in Schelog-style backtracking), eliminating O(depth) frame allocations per invocation.

func (*ComposableContinuation) BarrierValid added in v1.4.0 

func (p *ComposableContinuation) BarrierValid() *BarrierToken

BarrierValid returns the barrier identity token captured when this continuation was created. Used by applyComposableContinuation to detect barrier crossings.

func (*ComposableContinuation) Cont 

func (p *ComposableContinuation) Cont() *MachineContinuation

func (*ComposableContinuation) EqualTo 

func (p *ComposableContinuation) EqualTo(o values.Value) bool

func (*ComposableContinuation) IsVoid 

func (p *ComposableContinuation) IsVoid() bool

func (*ComposableContinuation) SchemeString 

func (p *ComposableContinuation) SchemeString() string

func (*ComposableContinuation) ThreadID added in v1.1.0 

func (p *ComposableContinuation) ThreadID() uint64

func (*ComposableContinuation) WindingStack 

func (p *ComposableContinuation) WindingStack() WindingStack

type ContinuationMarkSet added in v1.7.0 

type ContinuationMarkSet struct {
	// contains filtered or unexported fields
}

ContinuationMarkSet is an immutable snapshot of continuation marks collected from a walk of the continuation chain.

The frames slice contains per-frame mark slices, nearest frame first. Only frames with non-nil marks are included. Each frame is a []markEntry searched with eqIdentity (eq? semantics).

func CollectMarksFromContinuation added in v1.7.0 

func CollectMarksFromContinuation(cont *MachineContinuation, tag *PromptTag) *ContinuationMarkSet

CollectMarksFromContinuation walks a captured MachineContinuation chain and builds a ContinuationMarkSet snapshot. Used by the (continuation-marks cont) primitive to extract marks from a continuation captured via call/cc.

Starts from cont (nearest frame) and walks parent links, stopping at the first frame whose promptTag matches tag (inclusive). Pass DefaultPromptTag for an unbounded walk.

func (*ContinuationMarkSet) EqualTo added in v1.7.0 

func (p *ContinuationMarkSet) EqualTo(o values.Value) bool

func (*ContinuationMarkSet) First added in v1.7.0 

func (p *ContinuationMarkSet) First(key, defaultVal values.Value) values.Value

First returns the value for key from the nearest frame, or defaultVal if no frame contains the key. Uses eq? semantics (eqIdentity) for key comparison.

func (*ContinuationMarkSet) IsVoid added in v1.7.0 

func (p *ContinuationMarkSet) IsVoid() bool

func (*ContinuationMarkSet) SchemeString added in v1.7.0 

func (p *ContinuationMarkSet) SchemeString() string

func (*ContinuationMarkSet) ToList added in v1.7.0 

func (p *ContinuationMarkSet) ToList(key values.Value) values.Tuple

ToList returns a list of values for key across all frames, nearest first. Returns the empty list if no frame contains the key. Uses eq? semantics (eqIdentity) for key comparison.

func (*ContinuationMarkSet) ToListStar added in v1.7.0 

func (p *ContinuationMarkSet) ToListStar(keys []values.Value, noneVal values.Value) values.Tuple

ToListStar returns a list of vectors for multiple keys across all frames. Each vector corresponds to a frame that has at least one of the requested keys. Vector positions correspond to the keys slice; noneVal fills missing keys. Uses eq? semantics (eqIdentity) for key comparison.

Racket §10.5: continuation-mark-set->list*

type Debugger 

type Debugger struct {
	// contains filtered or unexported fields
}

Debugger manages breakpoints and stepping.

func NewDebugger 

func NewDebugger() *Debugger

NewDebugger creates a new debugger.

func (*Debugger) Breakpoints 

func (p *Debugger) Breakpoints() []*Breakpoint

Breakpoints returns all breakpoints.

func (*Debugger) CheckBreakpoint 

func (p *Debugger) CheckBreakpoint(mc *MachineContext) *Breakpoint

CheckBreakpoint checks if execution should break at current location.

func (*Debugger) Continue 

func (p *Debugger) Continue()

Continue resumes execution.

func (*Debugger) DisableBreakpoint 

func (p *Debugger) DisableBreakpoint(id BreakpointID) bool

DisableBreakpoint disables a breakpoint.

func (*Debugger) EnableBreakpoint 

func (p *Debugger) EnableBreakpoint(id BreakpointID) bool

EnableBreakpoint enables a breakpoint.

func (*Debugger) IsStepping 

func (p *Debugger) IsStepping() bool

IsStepping returns whether the debugger is in stepping mode.

func (*Debugger) OnBreak 

func (p *Debugger) OnBreak(fn func(mc *MachineContext, bp *Breakpoint))

OnBreak sets the callback for when a breakpoint is hit.

func (*Debugger) RemoveBreakpoint 

func (p *Debugger) RemoveBreakpoint(id BreakpointID) bool

RemoveBreakpoint removes a breakpoint.

func (*Debugger) SetBreakpoint 

func (p *Debugger) SetBreakpoint(file string, line, column int) BreakpointID

SetBreakpoint adds a breakpoint at the given source location.

func (*Debugger) ShouldStep 

func (p *Debugger) ShouldStep(mc *MachineContext) bool

ShouldStep checks if we should break due to stepping.

func (*Debugger) StepInto 

func (p *Debugger) StepInto()

StepInto enables step-into mode.

func (*Debugger) StepOut 

func (p *Debugger) StepOut(mc *MachineContext)

StepOut enables step-out mode.

func (*Debugger) StepOver 

func (p *Debugger) StepOver(mc *MachineContext)

StepOver enables step-over mode.

func (*Debugger) TriggerBreak 

func (p *Debugger) TriggerBreak(mc *MachineContext, bp *Breakpoint)

TriggerBreak calls the break callback if set.

type DisassembledInstruction added in v1.10.5 

type DisassembledInstruction struct {
	PC      int
	Op      string
	Arg     int32
	HasArg  bool   // true when Arg is meaningful (distinguishes unused from Arg=0)
	Slot    int    // decoded slot for local ops; -1 when not applicable
	Depth   int    // decoded depth for local ops; -1 when not applicable
	Target  int    // absolute PC for branch/save ops; -1 when not applicable
	Literal string // SchemeString() of resolved literal; "" when not applicable
	Binding string // name of cached binding's value; "" when not applicable
	SideOp  string // String() of InlinedOperation; "" when not applicable
	Source  string // "file:line:col" or ""
}

DisassembledInstruction holds the annotation for a single bytecode instruction.

type DisassembledTemplate added in v1.10.5 

type DisassembledTemplate struct {
	Name         string
	ParamCount   int
	IsVariadic   bool
	Doc          string
	Literals     []string // SchemeString() of each literal
	Bindings     []string // name of each cached binding
	Instructions []DisassembledInstruction
}

DisassembledTemplate holds the annotated disassembly of a NativeTemplate.

func Disassemble added in v1.10.5 

func Disassemble(tpl *NativeTemplate) DisassembledTemplate

Disassemble walks the template's bytecode and produces a DisassembledTemplate with annotations resolved per opcode category.

type DynamicWindFrame 

type DynamicWindFrame struct {
	Before Closure // Called when entering this extent
	After  Closure // Called when exiting this extent
	ID     uint64  // Unique identifier for extent matching
}

DynamicWindFrame represents a single dynamic-wind extent. Each frame tracks the before/after thunks for one dynamic-wind call.

R7RS §6.10: dynamic-wind establishes a dynamic extent during which the before and after thunks are called whenever control enters or exits.

Continuation-wind interaction (Friedman & Haynes 1985, Clinger et al. 1999). The winding stack W is separate from continuation chain K. 

W = [w₁, w₂, ...wₙ] where wᵢ = (before_i, after_i, id_i)

On continuation invocation from Wsrc to Wtgt:
  prefix = FindCommonWindingPrefix(Wsrc, Wtgt)
  UnwindTo(prefix):  call after_n, after_{n-1}, ... (innermost first)
  RewindTo(Wtgt):    call before_{prefix+1}, ... (outermost first)

Invariant: W is captured by value at call/cc time (copied into
  ComposableContinuation), NOT stored per continuation frame.
  W belongs to the dynamic extent, not the lexical continuation.
Constrains: RestoreWithWindingFrom (must compute prefix and run
  thunks in correct order). Sub-contexts inherit W from their parent
  via NewSubContext; NewSubContextWithWinding overrides for truncated
  stacks during unwind/exception cleanup.
Constrained by: CESK model (W is NOT part of K — it is orthogonal
  state). PushWind/PopWind opcodes maintain W during normal execution.

See BIBLIOGRAPHY.md "Dynamic-Wind" and "Continuation-Wind Interaction".

func NewDynamicWindFrame 

func NewDynamicWindFrame(before, after Closure) *DynamicWindFrame

NewDynamicWindFrame creates a new winding frame with a unique ID.

type EditPlan added in v1.5.0 

type EditPlan struct {
	// contains filtered or unexported fields
}

EditPlan collects non-overlapping bytecode edits for a NativeTemplate. Edits are applied in a single pass via Apply, which rewrites code, sourceRefs, and branch offsets, then garbage-collects unreferenced sideTable entries.

Apply remaps these Arg categories automatically:

  • PC offsets: Branch, BranchOnFalseValue, SaveContinuation
  • SideTable indices: Complex (unreferenced entries are GC'd)

These are stable across Apply and not touched:

  • Literal pool indices: LoadLiteral, LoadGlobal, StoreGlobal, PushLiteral, PushGlobal
  • Local indices: LoadLocal, StoreLocal, PushLocal
  • Stack offsets: PeekK

func NewEditPlan added in v1.5.0 

func NewEditPlan(tpl *NativeTemplate) *EditPlan

NewEditPlan creates a new edit plan for the given template.

func (*EditPlan) AddLiteral added in v1.5.0 

func (p *EditPlan) AddLiteral(v values.Value) int32

AddLiteral adds a value to the template's literal pool, with deduplication. Returns the index suitable for use in Instruction.Arg fields that reference the literal pool (OpLoadLiteral, OpLoadGlobal, OpStoreGlobal).

func (*EditPlan) Apply added in v1.5.0 

func (p *EditPlan) Apply() int

Apply rewrites the template according to all accumulated edits:

  1. Sorts and validates edits (panics on overlap)
  2. Builds a PC remap from old positions to new positions
  3. Fixes branch offsets for surviving original instructions
  4. Rebuilds code + sourceRefs, splicing in replacements
  5. Garbage-collects unreferenced sideTable entries, remaps OpComplex.Arg

Returns the net change in instruction count (negative means code shrunk).

func (*EditPlan) Delete added in v1.5.0 

func (p *EditPlan) Delete(start, end int)

Delete marks the range [start, end) for removal.

func (*EditPlan) HasEdits added in v1.5.0 

func (p *EditPlan) HasEdits() bool

HasEdits reports whether any edits have been added.

func (*EditPlan) Insert added in v1.5.0 

func (p *EditPlan) Insert(at int, instrs []Instruction, src uint32)

Insert inserts instrs before the instruction at position at.

func (*EditPlan) Replace added in v1.5.0 

func (p *EditPlan) Replace(start, end int, instrs []Instruction, src uint32)

Replace marks the range [start, end) for replacement with instrs. src is the source reference for all inserted instructions.

type ErrExceptionEscape 

type ErrExceptionEscape struct {
	Condition    values.Value          // The raised condition/object
	Continuable  bool                  // Whether handler can return
	Continuation *MachineContinuation  // Return point for continuable exceptions
	Handled      bool                  // Set true after handler processes it
	WindingStack WindingStack          // Winding stack at raise point (for proper unwinding)
	Source       *syntax.SourceContext // Source location where exception was raised
	StackTrace   StackTrace            // VM stack trace at raise point
}

ErrExceptionEscape signals an exception being raised through the call stack. It is used by raise and raise-continuable to propagate exceptions to handlers.

func (*ErrExceptionEscape) Error 

func (p *ErrExceptionEscape) Error() string

Error implements the error interface.

When Source is present and the condition is a NativeError, produces clean human-readable output like "file:5:3: error: division by zero". For non-NativeError conditions with Source, produces "file:5:3: exception: foo". When no Source is set, falls back to the original format for backward compat.

func (*ErrExceptionEscape) Unwrap added in v1.3.0 

func (p *ErrExceptionEscape) Unwrap() error

Unwrap returns the underlying error when the condition implements the error interface (e.g., *NativeError). This enables errors.Is/errors.As to traverse through ErrExceptionEscape into the wrapped error chain, supporting sentinel matching like errors.Is(err, werr.ErrDivisionByZero) from Go callers.

type ErrPromptAbort 

type ErrPromptAbort struct {
	Tag    *PromptTag
	Values []values.Value
}

ErrPromptAbort signals an abort to the nearest continuation prompt matching the given tag. It propagates up through Run() and is caught by RunWithEscapeHandling() or by call-with-continuation-prompt sub-contexts.

When caught, the handler finds the matching prompt frame, unwinds dynamic-wind extents, and invokes the prompt's handler with the abort values.

func (*ErrPromptAbort) Error 

func (p *ErrPromptAbort) Error() string

type ExceptionHandler 

type ExceptionHandler struct {
	// contains filtered or unexported fields
}

ExceptionHandler represents an installed exception handler. Handlers form a linked list (stack) for dynamic exception handling. When an exception is raised, handlers are invoked in reverse order of installation (most recent first).

func NewExceptionHandler 

func NewExceptionHandler(handler values.Callable, parent *ExceptionHandler) *ExceptionHandler

NewExceptionHandler creates a new exception handler with the given handler procedure and parent handler.

func (*ExceptionHandler) Handler 

func (p *ExceptionHandler) Handler() values.Callable

Handler returns the handler procedure.

func (*ExceptionHandler) Parent 

func (p *ExceptionHandler) Parent() *ExceptionHandler

Parent returns the previous handler in the chain.

type ExpanderCtx added in v1.10.5 

type ExpanderCtx interface {
	Env() *environment.EnvironmentFrame
	Expand(syntax.SyntaxValue) (syntax.SyntaxValue, error)
	ExpandOnce(syntax.SyntaxValue) (syntax.SyntaxValue, bool, error)
	IntroductionScope() *syntax.Scope
	SetIntroductionScope(*syntax.Scope)
	UseSiteScope() *syntax.Scope
	SetUseSiteScope(*syntax.Scope)
}

ExpanderCtx abstracts the macro expansion context so that code needing expansion capabilities can depend on this interface rather than the concrete ExpanderContext. This enables the future machine/compilation sub-package to provide ExpanderContext without circular imports back to machine/.

type ForeignClosure added in v1.5.0 

type ForeignClosure struct {
	// contains filtered or unexported fields
}

ForeignClosure wraps a Go function as a directly-callable Scheme procedure. Unlike MachineClosure, it holds the ForeignFunction directly and bypasses the bytecode VM — no template, no opcodes, no VM loop iteration.

func NewForeignClosure 

func NewForeignClosure(env *environment.EnvironmentFrame, pcnt int, variadic bool, fn ForeignFunction) *ForeignClosure

func (*ForeignClosure) AcceptsArity added in v1.5.0 

func (p *ForeignClosure) AcceptsArity(n int) bool

AcceptsArity reports whether this closure can be called with n arguments.

func (*ForeignClosure) Doc added in v1.10.3 

func (p *ForeignClosure) Doc() string

func (*ForeignClosure) Env added in v1.5.0 

func (p *ForeignClosure) Env() *environment.EnvironmentFrame

func (*ForeignClosure) EqualTo added in v1.5.0 

func (p *ForeignClosure) EqualTo(o values.Value) bool

EqualTo uses identity semantics — two foreign closures are equal only if they are the same pointer.

func (*ForeignClosure) Fn added in v1.5.0 

func (p *ForeignClosure) Fn() ForeignFunction

func (*ForeignClosure) IsVariadic added in v1.5.0 

func (p *ForeignClosure) IsVariadic() bool

func (*ForeignClosure) IsVoid added in v1.5.0 

func (p *ForeignClosure) IsVoid() bool

func (*ForeignClosure) Name added in v1.5.0 

func (p *ForeignClosure) Name() string

func (*ForeignClosure) ParameterCount added in v1.5.0 

func (p *ForeignClosure) ParameterCount() int

func (*ForeignClosure) SchemeString added in v1.5.0 

func (p *ForeignClosure) SchemeString() string

func (*ForeignClosure) SetDoc added in v1.10.3 

func (p *ForeignClosure) SetDoc(doc string)

func (*ForeignClosure) SetName added in v1.5.0 

func (p *ForeignClosure) SetName(name string)

func (*ForeignClosure) SetValidator added in v1.10.3 

func (p *ForeignClosure) SetValidator(v ForeignFunction)

SetValidator installs a contract validation function that runs before the implementation. Called during registration when contract enforcement is enabled.

func (*ForeignClosure) Validator added in v1.10.3 

func (p *ForeignClosure) Validator() ForeignFunction

Validator returns the installed contract validator, or nil if none.

type ForeignFunction 

type ForeignFunction func(mc CallContext) error

ForeignFunction is the signature for Go-implemented Scheme primitives. The CallContext provides access to arguments, the value register, and the cancellation context (via mc.Context()).

Most implementations only need CallContext methods (Arg, SetValue, SetValues, Authorizer, Context, EnvironmentFrame, Thread). Implementations that need full VM access (sub-context creation, continuation manipulation) should type-assert to *MachineContext.

type FreeIdResolution 

type FreeIdResolution struct {
	Global          *environment.GlobalIndex
	LocalScopes     []*syntax.Scope
	HasLocalBinding bool
	LibScope        *syntax.Scope
}

FreeIdResolution records how a free identifier in a syntax-rules template was bound at macro definition time. The match package uses this during template expansion to preserve hygiene.

Implements localScopesProvider, globalBindingProvider, hasLocalBindingProvider, and libraryScopeProvider from the match package.

func (*FreeIdResolution) GetGlobal 

func (p *FreeIdResolution) GetGlobal() *environment.GlobalIndex

GetGlobal implements the globalBindingProvider interface.

func (*FreeIdResolution) GetHasLocalBinding 

func (p *FreeIdResolution) GetHasLocalBinding() bool

GetHasLocalBinding implements the hasLocalBindingProvider interface.

func (*FreeIdResolution) GetLibraryScope added in v1.6.0 

func (p *FreeIdResolution) GetLibraryScope() *syntax.Scope

GetLibraryScope implements the libraryScopeProvider interface.

func (*FreeIdResolution) GetLocalScopes 

func (p *FreeIdResolution) GetLocalScopes() []*syntax.Scope

GetLocalScopes implements the localScopesProvider interface.

type FreeList added in v1.9.1 

type FreeList[T any] struct {
	// contains filtered or unexported fields
}

FreeList[T] is a type-safe, observable object pool backed by a mutex-guarded slice instead of sync.Pool. Unlike sync.Pool, the freelist is NOT cleared by the garbage collector, so recycled objects (and any capacity they retain) persist across GC cycles.

Use FreeList when the GC feedback loop makes sync.Pool ineffective: high allocation rates trigger frequent GC, which clears sync.Pool, causing more allocations. FreeList breaks this loop at the cost of no automatic shrinkage.

func NewFreeList added in v1.9.1 

func NewFreeList[T any](name string, newFn func() *T, resetFn func(*T)) *FreeList[T]

NewFreeList creates a FreeList[T] with the given name, constructor, and reset function. The freelist starts enabled.

func (*FreeList[T]) Acquire added in v1.9.1 

func (p *FreeList[T]) Acquire() *T

Acquire returns a recycled object from the freelist. If the freelist is empty or disabled, it calls newFn to allocate a new object.

func (*FreeList[T]) Drain added in v1.9.1 

func (p *FreeList[T]) Drain()

Drain clears all cached objects from the freelist.

func (*FreeList[T]) Name added in v1.9.1 

func (p *FreeList[T]) Name() string

Name returns the freelist's name.

func (*FreeList[T]) Release added in v1.9.1 

func (p *FreeList[T]) Release(v *T)

Release resets the object and appends it to the freelist. If disabled, the object is discarded after reset.

func (*FreeList[T]) SetEnabled added in v1.9.1 

func (p *FreeList[T]) SetEnabled(on bool)

SetEnabled toggles the freelist on or off. When disabled, Acquire calls newFn directly and Release discards after reset.

func (*FreeList[T]) Stats added in v1.9.1 

func (p *FreeList[T]) Stats() PoolSnapshot

Stats returns a point-in-time snapshot of the freelist's counters.

type InlinedOperation added in v1.4.0 

type InlinedOperation interface {
	Operation
	Apply(mc *MachineContext) (*MachineContext, error)
}

InlinedOperation is the interface for operations dispatched through the side table via OpComplex. These operations carry their own Apply method because the Run() loop delegates to them rather than inlining the logic.

type Instruction added in v1.4.0 

type Instruction struct {
	Op  OpCode
	Arg int32
}

Instruction is a single VM instruction for the switch-dispatch loop. Op selects the operation; Arg carries an immediate operand whose meaning depends on Op:

  • Zero-operand ops (Push, Pop, ...): Arg is unused (0).
  • Single-operand ops (Branch, LoadLiteral, ...): Arg is the offset, index, or depth.
  • Two-operand ops (LoadLocal, StoreLocal): Arg is bit-packed (slot in low 16, depth in high 16).
  • OpComplex: Arg is the index into the template's sideTable.

Size: 8 bytes (uint16 Op + 2 bytes padding + int32 Arg).

func (Instruction) String added in v1.4.0 

func (instr Instruction) String() string

String returns a human-readable representation of the instruction.

type LiteralIndex 

type LiteralIndex int

type MachineClosure 

type MachineClosure struct {
	// contains filtered or unexported fields
}

Linked closure (Church 1936, Landin 1964, Cardelli 1983). A closure is a pair of compiled code and the lexical environment at definition time. 

closure = ⟨λ, E⟩, where:
  λ = template  — compiled bytecode (NativeTemplate)
  E = env       — pointer to enclosing EnvironmentFrame

Access cost: O(1) creation (capture pointer), O(depth) free variable
  lookup (traverse parent chain). Flat closures invert this trade-off.

Invariant: E is a live pointer into the frame chain, not a copy.
  Mutations via set! are visible through the closure because the
  closure shares the frame, not a snapshot.
Constrains: OperationMakeClosure (must link E to runtime parent),
  Apply (always copies E to prevent aliasing and thread races).
Constrained by: de Bruijn addressing (free vars addressed by
  slot,depth in E's chain), CESK model (E is the environment component).

See BIBLIOGRAPHY.md "Linked Closure Representation".

func NewClosureWithTemplate 

func NewClosureWithTemplate(tpl *NativeTemplate, env *environment.EnvironmentFrame) *MachineClosure

func NewVMForeignClosure added in v1.5.0 

func NewVMForeignClosure(env *environment.EnvironmentFrame, pcnt int, variadic bool, fn ForeignFunction) *MachineClosure

NewVMForeignClosure creates a *MachineClosure backed by a ForeignFunction via a bytecode template (OpForeignFunctionCall + OpRestoreContinuation). Use this instead of NewForeignClosure for foreign functions that do nested VM execution (sub-context + Run), where the iterative VM loop prevents Go stack growth that applyForeign would cause.

func (*MachineClosure) AcceptsArity added in v1.5.0 

func (p *MachineClosure) AcceptsArity(n int) bool

AcceptsArity reports whether this closure can be called with n arguments. Fixed-arity closures require exactly paramCount args; variadic closures require at least paramCount-1 (the rest parameter collects the remainder).

func (*MachineClosure) Copy 

func (p *MachineClosure) Copy() *MachineClosure

func (*MachineClosure) Doc added in v1.10.7 

func (p *MachineClosure) Doc() string

Doc returns the closure's documentation string from its compiled template.

func (*MachineClosure) Env added in v1.5.0 

func (p *MachineClosure) Env() *environment.EnvironmentFrame

Env returns the closure's captured environment.

func (*MachineClosure) EqualTo 

func (p *MachineClosure) EqualTo(o values.Value) bool

func (*MachineClosure) IsVoid 

func (p *MachineClosure) IsVoid() bool

func (*MachineClosure) Name added in v1.10.7 

func (p *MachineClosure) Name() string

Name returns the closure's name from its compiled template.

func (*MachineClosure) SchemeString 

func (p *MachineClosure) SchemeString() string

func (*MachineClosure) Template 

func (p *MachineClosure) Template() *NativeTemplate

type MachineContext 

type MachineContext struct {
	// contains filtered or unexported fields
}

MachineContext represents the execution context of a virtual machine. It holds the current environment, values, evaluation stack, continuation, and program counter. It is created from a MachineContinuation and can be modified during execution.

func AcquireTopLevelContext added in v1.5.0 

func AcquireTopLevelContext(ctx context.Context, tpl *NativeTemplate, env *environment.EnvironmentFrame) *MachineContext

AcquireTopLevelContext returns a pooled MachineContext initialized for top-level execution (no parent continuation). This eliminates the intermediate MachineContinuation allocation that NewMachineContinuation + NewMachineContext would otherwise perform when parent is nil.

The caller MUST call ReleaseTopLevelContext after Run returns.

func NewMachineContext 

func NewMachineContext(ctx context.Context, cont *MachineContinuation) *MachineContext

NewMachineContext creates a new machine context with the given context and continuation. The context enables cancellation/timeout support in the VM loop. For callers that don't need cancellation, pass context.Background().

func NewMachineContextFromMachineClosure 

func NewMachineContextFromMachineClosure(ctx context.Context, cls *MachineClosure) *MachineContext

func NewThreadSubContext added in v1.3.0 

func NewThreadSubContext(params SubContextParams, thread *values.Thread) *MachineContext

NewThreadSubContext creates a sub-context for a thread using previously captured parent state. Unlike NewSubContext, this doesn't access the parent MachineContext fields, making it safe to call from a different goroutine. The thread parameter should be the new thread object, which provides the thread identity for the new context.

This function is specifically designed for SRFI-18 thread creation. For other uses of sub-contexts (like map, for-each, dynamic-wind), use NewSubContext instead.

func (*MachineContext) Apply 

func (p *MachineContext) Apply(mcls *MachineClosure, vs ...values.Value) (*MachineContext, error)

func (*MachineContext) ApplyCallable added in v1.2.0 

func (p *MachineContext) ApplyCallable(callable values.Value, args ...values.Value) (*MachineContext, error)

ApplyCallable dispatches a procedure call to the appropriate handler based on the callee's concrete type. This is the unified entry point for all Scheme procedure application, symmetric with OperationApply.

Supported callable types:

  • *MachineClosure: standard Scheme lambda
  • *ForeignClosure: Go foreign function (direct call, no bytecode)
  • *CaseLambdaClosure: R7RS case-lambda (§4.2.9)
  • *Parameter: R7RS parameter object (§4.2.6)
  • *ComposableContinuation: delimited continuation

Precondition: p.ctx must be set (always true for contexts created via NewMachineContext or NewSubContext).

func (*MachineContext) ApplyCaseLambda 

func (p *MachineContext) ApplyCaseLambda(clcls *CaseLambdaClosure, vs ...values.Value) (*MachineContext, error)

ApplyCaseLambda applies a case-lambda closure by finding the matching clause.

func (*MachineContext) Arg 

func (p *MachineContext) Arg(index int) values.Value

func (*MachineContext) Authorizer added in v1.7.0 

func (p *MachineContext) Authorizer() security.Authorizer

Authorizer returns the security authorizer from this context's namespace, or nil if none is set.

func (*MachineContext) BarrierValid added in v1.4.0 

func (p *MachineContext) BarrierValid() *BarrierToken

BarrierValid returns the barrier validity flag for the current context. Non-nil means execution is inside a with-continuation-barrier; the pointer identity distinguishes which barrier. Nil means no active barrier.

Escape closures and composable continuations use this to detect barrier crossings: if the capture-time pointer differs from the invocation-time pointer, the continuation would cross a barrier boundary.

func (*MachineContext) CallDepth 

func (p *MachineContext) CallDepth() int

CallDepth returns the depth of the current continuation stack.

func (*MachineContext) CaptureStackTrace 

func (p *MachineContext) CaptureStackTrace(maxDepth int) StackTrace

CaptureStackTrace walks the continuation chain and builds a stack trace.

func (*MachineContext) CaptureSubContextParams added in v1.3.0 

func (p *MachineContext) CaptureSubContextParams() SubContextParams

CaptureSubContextParams extracts the state needed to create a sub-context in a different goroutine. This is used by thread creation to avoid race conditions when accessing the parent MachineContext from a child goroutine (T4 from architectural review).

Call this in the parent goroutine before creating the child goroutine, then pass the result to NewThreadSubContext in the child goroutine.

func (*MachineContext) CollectContinuationMarks added in v1.7.0 

func (p *MachineContext) CollectContinuationMarks(tag *PromptTag) *ContinuationMarkSet

CollectContinuationMarks walks the continuation chain and builds a ContinuationMarkSet snapshot. Collects marks from the current frame and all continuation frames up to and including the nearest frame with a matching promptTag.

func (*MachineContext) Context 

func (p *MachineContext) Context() context.Context

Context returns the context for this machine context.

func (*MachineContext) Counters added in v1.1.0 

func (p *MachineContext) Counters() VMCounters

Counters returns a snapshot of the performance counters for this context.

func (*MachineContext) CurrentContinuation 

func (p *MachineContext) CurrentContinuation() *MachineContinuation

func (*MachineContext) CurrentLocation added in v1.13.14 

func (p *MachineContext) CurrentLocation() *values.DebugLocation

CurrentLocation returns the current source location as a values.DebugLocation, or nil if no source info is available. Implements values.DebugState.

func (*MachineContext) CurrentSource 

func (p *MachineContext) CurrentSource() *syntax.SourceContext

CurrentSource returns the source location for the current execution point. When the current template has no source (e.g., inside a foreign function), walks up the continuation chain to find the nearest call site with source info. Continuation PCs are return addresses (one past the call), so pc-1 gives the call site.

func (*MachineContext) Debugger 

func (p *MachineContext) Debugger() *Debugger

Debugger returns the attached debugger, or nil if none.

func (*MachineContext) DeleteMark added in v1.7.0 

func (p *MachineContext) DeleteMark(key values.Value)

DeleteMark removes the continuation mark for key from the current frame. Nils the slice when empty to maintain the "nil = zero-cost" invariant. Uses eq? semantics for key comparison. Deletion uses swap-with-last for O(1) removal; insertion order is not preserved.

func (*MachineContext) EnvironmentFrame 

func (p *MachineContext) EnvironmentFrame() *environment.EnvironmentFrame

func (*MachineContext) Error 

func (p *MachineContext) Error(msg string) *SchemeError

Error creates a SchemeError with the current source location and stack trace.

func (*MachineContext) EscapeCont 

func (p *MachineContext) EscapeCont() *MachineContinuation

EscapeCont returns the escape continuation for this context. This is set by foreign functions (like dynamic-wind) that need call/cc inside their sub-contexts to know where to continue after completion.

func (*MachineContext) Evals added in v1.10.5 

func (p *MachineContext) Evals() *Stack

Evals returns the eval stack for inspection (primarily for testing).

func (*MachineContext) ExceptionHandler 

func (p *MachineContext) ExceptionHandler() *ExceptionHandler

ExceptionHandler returns the current exception handler chain.

func (*MachineContext) ExpanderContext 

func (p *MachineContext) ExpanderContext() ExpanderCtx

ExpanderContext returns the expander context, or nil if not in expansion context.

func (*MachineContext) FindPrompt 

func (p *MachineContext) FindPrompt(tag *PromptTag) (*MachineContinuation, bool)

FindPrompt walks the continuation chain to find the nearest frame with a matching prompt tag. Also checks the context's own prompt tag (set by call-with-continuation-prompt on sub-contexts). Returns the matching frame and true, or nil and false.

When the prompt is on the context itself (not a continuation frame), returns nil and true — the caller should treat this as "prompt at the boundary of this sub-context" and slice the entire continuation chain.

func (*MachineContext) FormatStackTrace added in v1.13.14 

func (p *MachineContext) FormatStackTrace(maxDepth int) string

FormatStackTrace returns a human-readable stack trace string. Implements values.DebugState.

func (*MachineContext) GetImmediateMark added in v1.7.0 

func (p *MachineContext) GetImmediateMark(key values.Value) values.Value

GetImmediateMark returns the nearest mark for key, checking the current frame first, then the immediately saved continuation frame.

This is the correct lookup for call-with-immediate-continuation-mark: in tail position, with-continuation-mark sets the mark on the live frame (mc.marks); in non-tail position, SaveContinuation moves mc.marks to mc.cont and nils the live frame. Both cases are handled here.

func (*MachineContext) GetMark added in v1.7.0 

func (p *MachineContext) GetMark(key values.Value) values.Value

GetMark returns the continuation mark for key on the current frame, or nil if no mark is set. Uses eq? semantics for key comparison. Invariant: nil is used exclusively as the "not found" sentinel. Mark values are always non-nil Scheme values (GetValue never returns nil); SetMark must never be called with a nil val, as nil would be indistinguishable from absent.

func (*MachineContext) GetValue 

func (p *MachineContext) GetValue() values.Value

GetValue returns the first (or only) value from the value register. Returns Void if the register is empty.

func (*MachineContext) GetValues 

func (p *MachineContext) GetValues() MultipleValues

GetValues returns all values from the value register as a MultipleValues slice. For the single-value case this allocates a one-element slice; callers on the hot path should use GetValue instead.

func (*MachineContext) MaxCallDepth added in v1.3.0 

func (p *MachineContext) MaxCallDepth() uint64

MaxCallDepth returns the maximum call depth limit. 0 means unlimited.

func (*MachineContext) MaxStackSize added in v1.13.14 

func (p *MachineContext) MaxStackSize() uint64

MaxStackSize returns the maximum eval stack size limit. 0 means unlimited.

func (*MachineContext) NewSubContext 

func (p *MachineContext) NewSubContext() *MachineContext

NewSubContext creates a new MachineContext for running sub-calls (e.g., apply, map, for-each). The sub-context shares the global environment but has a fresh call stack, eval stack, and value register. This allows foreign functions to call Scheme closures without corrupting the parent context's state.

The parent's dynamic-wind winding stack is inherited automatically so that continuations captured inside the sub-context preserve the enclosing dynamic-wind context. For the rare sites that need a different stack (unwind truncation, exception cleanup), use NewSubContextWithWinding.

Note: Sub-contexts have isolated continuation chains (cont = nil). When call/cc captures a continuation inside a sub-context, it captures mc.Parent() which refers to the sub-context's chain (nil). For continuations to escape back to the outer context, the escape error propagates up through the call stack and is handled by RunWithEscapeHandling at the top level.

The parentMC field tracks the parent context, allowing call/cc to find an outer continuation for proper R7RS continuation semantics when captured inside sub-contexts.

The escapeCont field is inherited, allowing nested sub-contexts to know where execution should continue after their completion (set by dynamic-wind and similar constructs).

func (*MachineContext) NewSubContextWithTemplate added in v1.13.14 

func (p *MachineContext) NewSubContextWithTemplate(
	tpl *NativeTemplate,
	env *environment.EnvironmentFrame,
) *MachineContext

NewSubContextWithTemplate creates a sub-context configured to execute the given template in the given environment. This is the correct way for primitives like eval and load to create execution contexts — it propagates all parent fields automatically via NewSubContext, preventing the "forgotten field" bug class that NewMachineContext + manual setters is vulnerable to.

The template and env override NewSubContext's defaults (nil template, parent's TopLevel env). pc starts at 0 (pool zero-value).

func (*MachineContext) NewSubContextWithWinding added in v1.10.5 

func (p *MachineContext) NewSubContextWithWinding(windingStack WindingStack) *MachineContext

NewSubContextWithWinding creates a sub-context with an explicit winding stack instead of inheriting the parent's. Use this only when the sub-context must run with a winding stack that differs from the parent — for example, a truncated stack during unwind (machine_context_winding.go) or exception cleanup (prim_exceptions.go). All other sub-context creation should use NewSubContext.

func (*MachineContext) PC 

func (p *MachineContext) PC() int

func (*MachineContext) Parent 

func (p *MachineContext) Parent() *MachineContinuation

func (*MachineContext) ParentMC 

func (p *MachineContext) ParentMC() *MachineContext

ParentMC returns the parent machine context (for sub-contexts), or nil for top-level contexts.

func (*MachineContext) PopContinuation 

func (p *MachineContext) PopContinuation() (*MachineContinuation, error)

PopContinuation pops the current continuation from the machine context and returns it. It restores the machine context to the state saved in the popped continuation. Returns ErrContinuationUnderflow if callDepth would go below zero (compiler bug).

Note: Unlike Restore(), we do NOT copy evals here because PopContinuation is used for normal function return where the continuation is consumed once. Restore() is used for continuation re-entry (call/cc) where the same continuation may be invoked multiple times, requiring the copy to prevent stack corruption.

func (*MachineContext) PopExceptionHandler 

func (p *MachineContext) PopExceptionHandler() *ExceptionHandler

PopExceptionHandler pops the current exception handler from the stack and returns it. Returns nil if no handler is installed.

func (*MachineContext) PopWindingFrame 

func (p *MachineContext) PopWindingFrame() *DynamicWindFrame

PopWindingFrame removes the innermost frame from the winding stack.

func (*MachineContext) PromptTag 

func (p *MachineContext) PromptTag() *PromptTag

PromptTag returns the prompt tag for this context, or nil.

func (*MachineContext) PushExceptionHandler 

func (p *MachineContext) PushExceptionHandler(handler values.Callable)

PushExceptionHandler pushes a new exception handler onto the handler stack.

func (*MachineContext) PushWindingFrame 

func (p *MachineContext) PushWindingFrame(frame *DynamicWindFrame)

PushWindingFrame adds a frame to the winding stack.

func (*MachineContext) ResolveParameterValue added in v1.7.0 

func (p *MachineContext) ResolveParameterValue(param *Parameter) values.Value

ResolveParameterValue returns the effective value of a parameter, checking continuation marks (from parameterize) before falling back to the base value. This is the Go-side equivalent of calling the parameter with 0 args.

func (*MachineContext) Restore 

func (p *MachineContext) Restore(cont *MachineContinuation)

func (*MachineContext) RestoreAndRelease added in v1.4.0 

func (p *MachineContext) RestoreAndRelease(cont *MachineContinuation)

RestoreAndRelease is the fast path for normal function return. It transfers the continuation's state into the MachineContext (like Restore) but avoids copying evals — instead it transfers ownership directly and pools the consumed frame. This is safe because normal return consumes the frame exactly once; call/cc and escape paths must use Restore (which copies).

Shared frames (marked by MarkChainShared during call/cc capture) cannot be pooled because a captured continuation may re-invoke them. For shared frames, evals are copied (like Restore) and the frame is left for GC instead of pooling.

The sequence for unshared frames:

  1. Release mc's current evals to the stack pool (it's dead after restore)
  2. Transfer cont's evals directly to mc (no copy)
  3. Nil cont.evals so releaseContinuation won't double-release it
  4. Pool the consumed continuation frame

func (*MachineContext) RestoreWithWinding 

func (p *MachineContext) RestoreWithWinding(cont *MachineContinuation, targetStack WindingStack) error

RestoreWithWinding restores a continuation with proper dynamic-wind handling. It unwinds from the current dynamic extent, rewinds to the target extent, then restores the machine state.

If cont is nil (continuation captured in a sub-context), we still perform the winding operations but don't restore machine state - the caller should handle continued execution appropriately.

func (*MachineContext) RestoreWithWindingFrom 

func (p *MachineContext) RestoreWithWindingFrom(cont *MachineContinuation, sourceStack, targetStack WindingStack) error

RestoreWithWindingFrom restores a continuation with proper dynamic-wind handling, using an explicit source winding stack instead of the current context's stack.

This is needed when the escape originated from a sub-context that has a different winding stack than the context where RestoreWithWinding is called. For example, when call/cc captures inside a sub-context and the escape propagates up, the source winding stack (where the escape happened) may have frames that the top-level context doesn't know about.

Parameters:

  • cont: The continuation to restore to
  • sourceStack: The winding stack where the escape originated (for unwinding)
  • targetStack: The winding stack to restore to (for rewinding)

func (*MachineContext) RewindTo 

func (p *MachineContext) RewindTo(target WindingStack, commonDepth int) error

RewindTo runs before thunks from common ancestor to target depth. Returns error if any before thunk fails.

func (*MachineContext) Run 

func (p *MachineContext) Run() error

Run executes the VM loop starting from the current pc. The pc is NOT reset here - callers are responsible for ensuring the correct initial pc:

  • NewMachineContext copies pc from the continuation (typically 0 for fresh execution)
  • Apply sets pc = 0 for fresh closure invocation
  • Restore sets pc from the saved continuation for resumption

This design allows continuation resumption (e.g., raise-continuable) to work correctly by preserving the pc set by Restore rather than unconditionally resetting to 0.

Dispatch: Run always uses switch-dispatch over integer opcodes.

Context cancellation: The loop checks p.ctx.Done() every 1024 ops, allowing preemption via context.WithTimeout or context.WithCancel. This enables:

  • Test timeouts that actually stop execution
  • REPL interrupt support (Ctrl+C)
  • Resource management for long-running computations

Run executes the VM loop using switch-dispatch with integer opcodes. Hot-path operations (Wave 1-3) are inlined as switch cases; complex operations (closures, macros, FFI) are dispatched via OpComplex to the template's sideTable.

Set the context via SetContext() before calling Run().

func (*MachineContext) RunWithEscapeHandling 

func (p *MachineContext) RunWithEscapeHandling() error

RunWithEscapeHandling runs the VM loop, handling continuation escapes that weren't caught by an enclosing call/cc. This is used at the top level (REPL and file execution) to catch continuations invoked outside their original dynamic extent.

When a continuation captured inside a foreign function (like dynamic-wind's thunk) is invoked from outside, the escape error propagates up. This method catches it and restores the continuation with proper dynamic-wind handling.

For continuations captured inside sub-contexts (like dynamic-wind thunks):

  • Continuation: the inner state (inside the thunk)
  • EscapeCont: the outer continuation (after the original sub-context would have completed)

After the inner execution completes and unwinds, if there's a pending escape continuation, execution continues from there.

When execution completes normally (Run returns nil), any remaining frames on the winding stack are unwound (after thunks are called).

func (*MachineContext) SaveContinuation 

func (p *MachineContext) SaveContinuation(off int) error

SaveContinuation pushes a new continuation onto the machine context with the given offset to the current program counter. Returns ErrCallDepthExceeded if the call depth limit has been reached.

Note: callDepth is incremented BEFORE calling NewMachineContinuationFromMachineContext. The continuation's own callDepth is derived from mc.cont (the parent pointer), not from mc.callDepth, so this pre-increment does not affect the continuation's cached depth. See the comment on NewMachineContinuationFromMachineContext for why this matters.

func (*MachineContext) SetBarrierValid added in v1.4.0 

func (p *MachineContext) SetBarrierValid(v *BarrierToken)

SetBarrierValid sets the barrier identity token on this context. Called by PrimCallWithContinuationBarrier to mark the sub-context as inside a barrier.

func (*MachineContext) SetContext 

func (p *MachineContext) SetContext(ctx context.Context)

SetContext sets the context for this machine context. This should be called before Run() to enable context cancellation/timeout.

func (*MachineContext) SetDebugger 

func (p *MachineContext) SetDebugger(d *Debugger)

SetDebugger attaches a debugger to this context.

func (*MachineContext) SetEscapeCont 

func (p *MachineContext) SetEscapeCont(cont *MachineContinuation)

SetEscapeCont sets the escape continuation for this context.

func (*MachineContext) SetExceptionHandler 

func (p *MachineContext) SetExceptionHandler(h *ExceptionHandler)

SetExceptionHandler sets the exception handler chain.

func (*MachineContext) SetExpanderContext 

func (p *MachineContext) SetExpanderContext(ctx ExpanderCtx)

SetExpanderContext sets the expander context for this machine context. This is called when invoking macro transformers to enable syntax-local-* primitives.

func (*MachineContext) SetMark added in v1.7.0 

func (p *MachineContext) SetMark(key, val values.Value)

SetMark sets a continuation mark on the current frame using eq? semantics. Updates an existing entry with the same key, or appends a new one.

func (*MachineContext) SetMaxCallDepth added in v1.3.0 

func (p *MachineContext) SetMaxCallDepth(n uint64)

SetMaxCallDepth sets the maximum call depth limit. 0 means unlimited.

func (*MachineContext) SetMaxStackSize added in v1.13.14 

func (p *MachineContext) SetMaxStackSize(n uint64)

SetMaxStackSize sets the maximum eval stack size limit. 0 means unlimited.

func (*MachineContext) SetPC 

func (p *MachineContext) SetPC(v int)

SetPC sets the program counter. Used by PrimCallCC for inline lambda execution.

func (*MachineContext) SetPromptTag 

func (p *MachineContext) SetPromptTag(tag *PromptTag)

SetPromptTag sets the prompt tag on this context. Used by call-with-continuation-prompt to mark sub-contexts as prompt boundaries.

func (*MachineContext) SetThread added in v1.1.0 

func (p *MachineContext) SetThread(t *values.Thread)

SetThread sets the SRFI-18 thread identity on this context. Both the thread object and its ID are stored for efficient comparison.

func (*MachineContext) SetValue 

func (p *MachineContext) SetValue(v values.Value)

SetValue stores a single value in the value register without allocating. This is the hot path: every LoadLocal, LoadGlobal, LoadLiteral, Pull, Pop, MakeClosure, etc. goes through here.

func (*MachineContext) SetValues 

func (p *MachineContext) SetValues(vs ...values.Value)

SetValues sets the value register. For a single value this uses the zero-allocation fast path (singleValue); for multiple values it falls back to the multiValues slice.

func (*MachineContext) SetWindingStack 

func (p *MachineContext) SetWindingStack(stack WindingStack)

SetWindingStack sets the winding stack. Used by tests; production code should prefer NewSubContextWithWinding for override sites.

func (*MachineContext) SliceContinuationAt 

func (p *MachineContext) SliceContinuationAt(prompt *MachineContinuation) *MachineContinuation

SliceContinuationAt deep-copies the continuation chain segment from p.cont down to (but not including) the prompt frame. The returned chain's bottom frame has parent = nil, making it a standalone segment suitable for composable continuation capture.

func (*MachineContext) Template 

func (p *MachineContext) Template() *NativeTemplate

func (*MachineContext) Thread added in v1.1.0 

func (p *MachineContext) Thread() *values.Thread

Thread returns the SRFI-18 thread object for this context, or nil for the primordial thread.

func (*MachineContext) ThreadID added in v1.1.0 

func (p *MachineContext) ThreadID() uint64

ThreadID returns the SRFI-18 thread ID for this context. 0 means the primordial thread (main goroutine).

func (*MachineContext) UnwindTo 

func (p *MachineContext) UnwindTo(commonDepth int) error

UnwindTo runs after thunks from innermost to the common ancestor. Returns error if any after thunk fails.

func (*MachineContext) WindingStack 

func (p *MachineContext) WindingStack() WindingStack

WindingStack returns the current winding stack.

func (*MachineContext) WrapError 

func (p *MachineContext) WrapError(err error, msg string) *SchemeError

WrapError wraps an existing error with the current source location and stack trace.

type MachineContinuation 

type MachineContinuation struct {
	// contains filtered or unexported fields
}

func NewMachineContinuation 

func NewMachineContinuation(parent *MachineContinuation, tpl *NativeTemplate, env *environment.EnvironmentFrame) *MachineContinuation

NewMachineContinuation creates a new machine continuation with the given parent, template, environment frame, and initial values.

func NewMachineContinuationFromMachineContext 

func NewMachineContinuationFromMachineContext(mc *MachineContext, off int) *MachineContinuation

NewMachineContinuationFromMachineContext creates a new machine continuation from the given machine context and an offset to the program counter. The new continuation inherits the environment, template, and evaluation stack from the machine context.

callDepth derivation: the new frame's parent is mc.cont, so its depth is derived from mc.cont's cached depth — NOT from mc.callDepth. These values differ because SaveContinuation pre-increments mc.callDepth before calling this function, but other callers do not:

  • SaveContinuation: mc.callDepth already incremented → mc.callDepth != chain length
  • PrimCallCC sub-context path (prim_control.go): mc.callDepth == 0, mc.cont == nil
  • PrimDynamicWind escape cont (prim_control.go): mc.callDepth == chain length

Using mc.callDepth - 1 would underflow to -1 in the PrimCallCC case (mc.callDepth == 0). The parent-pointer formula is correct for all callers and immune to underflow.

func NewMachineContinuationWithPrompt 

func NewMachineContinuationWithPrompt(parent *MachineContinuation, tpl *NativeTemplate, env *environment.EnvironmentFrame, tag *PromptTag, handler Closure) *MachineContinuation

NewMachineContinuationWithPrompt creates a continuation frame that acts as a continuation prompt. The tag identifies the prompt for abort/capture, and the handler is invoked when an abort reaches this prompt.

func (*MachineContinuation) CallDepth 

func (p *MachineContinuation) CallDepth() int

CallDepth returns the depth of the continuation stack. The depth is cached in each frame at creation time, so this is O(1).

func (*MachineContinuation) Copy 

func (p *MachineContinuation) Copy() *MachineContinuation

func (*MachineContinuation) DeepCopy 

func (p *MachineContinuation) DeepCopy() *MachineContinuation

DeepCopy creates a deep copy of the entire continuation chain. Each frame in the chain is copied, with parent pointers updated to point to the copied frames. This is needed for composable continuations which must be safely re-invoked multiple times.

func (*MachineContinuation) EnvironmentFrame 

func (p *MachineContinuation) EnvironmentFrame() *environment.EnvironmentFrame

func (*MachineContinuation) EqualTo 

func (p *MachineContinuation) EqualTo(o values.Value) bool

func (*MachineContinuation) IsVoid 

func (p *MachineContinuation) IsVoid() bool

func (*MachineContinuation) MarkChainShared added in v1.4.0 

func (p *MachineContinuation) MarkChainShared()

MarkChainShared marks every frame in the continuation chain as shared. Shared frames are not pooled by RestoreAndRelease — their evals are copied instead of transferred, preserving them for re-invocation.

Early-exits when a frame is already shared: all ancestors must already be shared from a prior capture (sharing propagates toward the root).

func (*MachineContinuation) PC 

func (p *MachineContinuation) PC() int

func (*MachineContinuation) Parent 

func (p *MachineContinuation) Parent() *MachineContinuation

func (*MachineContinuation) PromptHandler 

func (p *MachineContinuation) PromptHandler() Closure

func (*MachineContinuation) PromptTag 

func (p *MachineContinuation) PromptTag() *PromptTag

func (*MachineContinuation) PushValues 

func (p *MachineContinuation) PushValues(v ...values.Value)

PushValues appends values to the continuation's value register. If the register currently holds a single value, it is promoted to the multi-value representation before appending. This promote-then-append pattern avoids losing the existing single value when transitioning to the multi-value path.

func (*MachineContinuation) SchemeString 

func (p *MachineContinuation) SchemeString() string

func (*MachineContinuation) SetPC 

func (p *MachineContinuation) SetPC(v int)

func (*MachineContinuation) SetPromptHandler 

func (p *MachineContinuation) SetPromptHandler(h Closure)

func (*MachineContinuation) SetPromptTag 

func (p *MachineContinuation) SetPromptTag(t *PromptTag)

func (*MachineContinuation) Template 

func (p *MachineContinuation) Template() *NativeTemplate

func (*MachineContinuation) ThreadID added in v1.1.0 

func (p *MachineContinuation) ThreadID() uint64

type MacroEvaluator added in v1.10.5 

type MacroEvaluator interface {
	// EvalTemplate evaluates a compiled template in the given environment
	// and returns the resulting value. Used by compileAndEvalLambdaTransformer
	// for define-syntax lambda transformers at compile time.
	EvalTemplate(ctx context.Context, tpl *NativeTemplate, env *environment.EnvironmentFrame) (values.Value, error)

	// InvokeTransformer calls a closure as a macro transformer.
	// expanderCtx is set on the VM context for auxiliary syntax
	// hygiene (R7RS Section 4.3.2); nil is valid when no hygiene context
	// is needed (e.g. ExpandOnce). args are passed to Apply — one arg for
	// syntax-rules/lambda transformers, three for ER macros (form, rename,
	// compare). On success, the caller receives the MachineContext with the
	// result in the value register and must call ReleaseSubContext when done.
	InvokeTransformer(ctx context.Context, cls Closure, expanderCtx ExpanderCtx, args ...values.Value) (*MachineContext, error)
}

MacroEvaluator abstracts VM execution for the compiler and expander so that compile-time evaluation and transformer invocation can be tested and wired without depending on the concrete MachineContext construction path.

func NewVMMacroEvaluator added in v1.10.5 

func NewVMMacroEvaluator() MacroEvaluator

NewVMMacroEvaluator returns a MacroEvaluator backed by the real VM.

type MultipleValues 

type MultipleValues []values.Value

MultipleValues represents multiple return values from a function.

func NewMultipleValues 

func NewMultipleValues(values ...values.Value) MultipleValues

NewMultipleValues creates a new MultipleValues from the given values.

func (MultipleValues) Copy 

func (p MultipleValues) Copy() MultipleValues

Copy creates a copy of the MultipleValues.

func (MultipleValues) EqualTo 

func (p MultipleValues) EqualTo(o values.Value) bool

EqualTo checks if the MultipleValues is equal to another value.

func (MultipleValues) IsVoid 

func (p MultipleValues) IsVoid() bool

IsVoid returns true if the MultipleValues represents 'void' - either

func (MultipleValues) Len 

func (p MultipleValues) Len() int

Len returns the number of values in the MultipleValues.

func (MultipleValues) SchemeString 

func (p MultipleValues) SchemeString() string

SchemeString returns the Scheme representation of the MultipleValues.

type NamedCallable added in v1.13.14 

type NamedCallable interface {
	Name() string
	Doc() string
}

NamedCallable is implemented by callable values that carry a name and documentation string. MachineClosure, ForeignClosure, and CaseLambdaClosure all satisfy this interface.

type NativeTemplate 

type NativeTemplate struct {
	// contains filtered or unexported fields
}

func NewEmptyNativeTemplate added in v1.2.0 

func NewEmptyNativeTemplate() *NativeTemplate

NewEmptyNativeTemplate creates a new NativeTemplate with default empty parameters. This is used when a template is initialized without any known parameters or operations yet.

func NewNativeTemplate 

func NewNativeTemplate(pcnt int, vcnt int, vd bool, operations ...Operation) *NativeTemplate

func (*NativeTemplate) AppendCachedBinding added in v1.5.0 

func (p *NativeTemplate) AppendCachedBinding(bd *environment.Binding) int32

AppendCachedBinding adds a *Binding to the cached bindings array, deduplicating by pointer identity. Returns the index for use as an OpLoadCachedBinding/OpPushCachedBinding operand.

func (*NativeTemplate) AppendInstruction added in v1.4.0 

func (p *NativeTemplate) AppendInstruction(instr Instruction)

AppendInstruction appends a single instruction with no source attribution.

func (*NativeTemplate) AppendInstructionWithSource added in v1.4.0 

func (p *NativeTemplate) AppendInstructionWithSource(src *syntax.SourceContext, instr Instruction)

AppendInstructionWithSource appends a single instruction to the integer-dispatch bytecode and tags it with the given source context.

func (*NativeTemplate) AppendOperations 

func (p *NativeTemplate) AppendOperations(ops ...Operation)

AppendOperations appends operations with no source attribution (index 0 = nil). Converts operations to instructions using AppendOperationsWithSource.

func (*NativeTemplate) AppendOperationsWithSource added in v1.4.0 

func (p *NativeTemplate) AppendOperationsWithSource(src *syntax.SourceContext, ops ...Operation)

AppendOperationsWithSource converts operations to instructions and tags each with the given source. Wave 1-3 operations become direct switch cases; complex operations go through the sideTable and are dispatched via OpComplex. This is a public method for test use.

func (*NativeTemplate) AppendSideTableOp added in v1.4.0 

func (p *NativeTemplate) AppendSideTableOp(op InlinedOperation) Instruction

AppendSideTableOp adds a complex operation to the side table and returns an OpComplex instruction that references it.

func (*NativeTemplate) CachedBindings added in v1.10.5 

func (p *NativeTemplate) CachedBindings() []*environment.Binding

CachedBindings returns the compile-time resolved bindings array. Used by the disassembler to annotate binding references.

func (*NativeTemplate) Code added in v1.4.0 

func (p *NativeTemplate) Code() []Instruction

Code returns the integer-dispatch bytecode slice.

func (*NativeTemplate) CodeLen added in v1.4.0 

func (p *NativeTemplate) CodeLen() int

CodeLen returns the current code[] length (number of instructions emitted).

func (*NativeTemplate) Copy 

func (p *NativeTemplate) Copy() *NativeTemplate

func (*NativeTemplate) DeduplicateLiteral 

func (p *NativeTemplate) DeduplicateLiteral(v values.Value) values.Value

DeduplicateLiteral deduplicates the given value using the template's literal pool. For composite values (pairs and vectors), all elements are deduplicated recursively. Returns the deduplicated value.

func (*NativeTemplate) Doc added in v1.10.3 

func (p *NativeTemplate) Doc() string

func (*NativeTemplate) EqualTo 

func (p *NativeTemplate) EqualTo(o values.Value) bool

func (*NativeTemplate) IncrementParameterCount added in v1.10.5 

func (p *NativeTemplate) IncrementParameterCount()

IncrementParameterCount adds one to the parameter count.

func (*NativeTemplate) IsVariadic 

func (p *NativeTemplate) IsVariadic() bool

func (*NativeTemplate) IsVoid 

func (p *NativeTemplate) IsVoid() bool

func (*NativeTemplate) Literals added in v1.5.0 

func (p *NativeTemplate) Literals() MultipleValues

Literals returns the literals pool.

func (*NativeTemplate) MaybeAppendLiteral 

func (p *NativeTemplate) MaybeAppendLiteral(v values.Value) LiteralIndex

func (*NativeTemplate) Name 

func (p *NativeTemplate) Name() string

func (*NativeTemplate) Operations 

func (p *NativeTemplate) Operations() Operations

Operations reconstructs the operation sequence from the bytecode. Converts Instructions back to Operation values for compatibility with existing code that expects Operations (e.g., tests, EqualTo).

func (*NativeTemplate) Optimize added in v1.5.0 

func (p *NativeTemplate) Optimize()

Optimize performs a peephole optimization pass on the template's bytecode. It removes dead instructions identified by pattern-matching rules, fixes branch offsets to account for removed instructions, and compacts the code and source reference arrays in parallel.

Superinstruction formation (Ertl & Gregg 2003). Fusing adjacent instructions reduces dispatch overhead in the Run() switch loop. 

Fusions:
  Load* + Push  → Push*       (eliminates 1 dispatch)
  Pull + Apply  → PullApply   (eliminates 1 dispatch)
  SaveCont + PushCachedBinding ... PullApply
              → CallForeignCached  (eliminates ~5 dispatches)

Cost model: each fusion saves one (fetch opcode + switch branch).
  In switch-dispatch interpreters, dispatch dominates execution time.

Invariant: fusions must not change observable semantics. Branch
  offsets are recomputed after compaction.
Constrains: Run() must implement fused opcodes with identical
  semantics to the original sequence.
Constrained by: must preserve semantic equivalence of fused
  instruction sequences.

See BIBLIOGRAPHY.md "Superinstruction Formation".

After compacting its own code, Optimize recurses into any *NativeTemplate values in the literals pool (lambda closures compiled as sub-templates).

Idempotent: a second call finds nothing to remove.

func (*NativeTemplate) ParameterCount 

func (p *NativeTemplate) ParameterCount() int

func (*NativeTemplate) PatchInstructionArg added in v1.4.0 

func (p *NativeTemplate) PatchInstructionArg(codeIdx int, arg int32)

PatchInstructionArg updates the Arg field of the instruction at code[codeIdx]. Used for patching branch offsets and continuation save offsets after the target PC is known.

func (*NativeTemplate) SchemeString 

func (p *NativeTemplate) SchemeString() string

func (*NativeTemplate) SetDoc added in v1.10.3 

func (p *NativeTemplate) SetDoc(doc string)

func (*NativeTemplate) SetName 

func (p *NativeTemplate) SetName(name string)

func (*NativeTemplate) SetVariadic added in v1.10.5 

func (p *NativeTemplate) SetVariadic()

SetVariadic marks this template as accepting a variadic rest argument.

func (*NativeTemplate) SideTable added in v1.4.0 

func (p *NativeTemplate) SideTable() []InlinedOperation

SideTable returns the complex operations referenced by OpComplex instructions.

func (*NativeTemplate) SourceAt 

func (p *NativeTemplate) SourceAt(pc int) *syntax.SourceContext

SourceAt returns the source location for the operation at pc. Returns nil if pc is out of bounds or no source was recorded. O(1) lookup via the parallel sourceRefs array.

func (*NativeTemplate) ValueCount 

func (p *NativeTemplate) ValueCount() int

type OpCode added in v1.4.0 

type OpCode uint16

OpCode is an integer opcode for the switch-dispatch VM loop. Operations migrated from interface dispatch to integer dispatch get a dedicated OpCode. Complex operations that remain as interface values use OpComplex with a side table index.

Adding a new opcode requires changes in:

  1. opcode.go — add OpXxx constant and entry in opcodeTable (name + metadata flags)
  2. machine_context.go Run() — add dispatch case in the main switch
  3. native_template.go — add cases in both operationToInstruction() and instructionToOperation()
  4. operation_xxx.go — create new operation type (or add to existing file)
  5. compile_*.go — add compiler method to emit the new opcode
  6. Relevant _test.go files
  7. peephole.go — if the new op participates in fusion/chaining (e.g. loadToFusedPush)

For promoted primitive ops specifically, see the guide comment at the top of call_promoted.go — promoted ops have a different (smaller) set of edit sites. 

const (
	OpInvalid OpCode = iota

	// Wave 1: zero-operand operations
	OpPush
	OpPop
	OpPull
	OpLoadVoid
	OpDrop
	OpPopEnv
	OpApply
	OpUnpackListToStack
	OpRestoreContinuation

	// Wave 2: single-operand operations (Arg = offset, index, or depth)
	OpBranchOnFalseValue
	OpBranch
	OpSaveContinuation
	OpLoadLiteral
	OpLoadGlobal
	OpStoreGlobal
	OpPeekK
	OpPushEnv // Push new env frame with Arg local slots

	// Wave 3: two-operand operations (Arg = bit-packed slot|depth)
	OpLoadLocal
	OpStoreLocal

	// Wave 4: fused push operations (Arg = same as unfused Load variant)
	OpPushLiteral // LoadLiteral + Push
	OpPushGlobal  // LoadGlobal + Push
	OpPushLocal   // LoadLocal + Push

	// Wave 5: fused call operations (zero-operand)
	OpPullApply // Pull + Apply

	// Wave 5: promoted complex operations (zero-operand)
	OpMakeClosure // MakeClosure (was OpComplex)

	// Wave 6: cached binding operations (Arg = index into cachedBindings)
	OpLoadCachedBinding // Load from compile-time resolved *Binding
	OpPushCachedBinding // LoadCachedBinding + Push (fused)

	// Wave 7: direct foreign call operations (Arg = index into cachedBindings)
	// Emitted by peephole only — compiler never produces these.
	OpCallForeignCached     // Non-tail: call ForeignClosure, then mc.pc++
	OpCallForeignCachedTail // Tail: call ForeignClosure, then returnImmediate()

	// Wave 8: general call fusion (Arg = same encoding as PushLocal/PushCachedBinding)
	// Fused PushLocal/PushCachedBinding + PullApply for non-foreign callables.
	// Emitted by peephole only — compiler never produces these.
	OpCallLocal         // Resolve local binding, drain args, ApplyCallable
	OpCallCachedBinding // Resolve cached binding, drain args, ApplyCallable

	// Wave 9: promoted primitive operations (Arg = index into cachedBindings)
	// Inline the hot primitive logic directly, bypassing arity check, arg
	// binding, and indirect function call. Emitted by peephole only when
	// the cached binding holds a known promoted ForeignClosure.
	OpEqQ           // Non-tail inlined eq?
	OpEqQTail       // Tail inlined eq?
	OpVectorQ       // Non-tail inlined vector?
	OpVectorQTail   // Tail inlined vector?
	OpVectorRef     // Non-tail inlined vector-ref
	OpVectorRefTail // Tail inlined vector-ref
	OpNullQ         // Non-tail inlined null?
	OpNullQTail     // Tail inlined null?
	OpPairQ         // Non-tail inlined pair?
	OpPairQTail     // Tail inlined pair?
	OpCar           // Non-tail inlined car
	OpCarTail       // Tail inlined car
	OpCdr           // Non-tail inlined cdr
	OpCdrTail       // Tail inlined cdr
	OpAdd           // Non-tail inlined 2-arg +
	OpAddTail       // Tail inlined 2-arg +
	OpSub           // Non-tail inlined 2-arg -
	OpSubTail       // Tail inlined 2-arg -
	OpNumLt         // Non-tail inlined 2-arg <
	OpNumLtTail     // Tail inlined 2-arg <
	OpNumLe         // Non-tail inlined 2-arg <=
	OpNumLeTail     // Tail inlined 2-arg <=
	OpNumGt         // Non-tail inlined 2-arg >
	OpNumGtTail     // Tail inlined 2-arg >
	OpNumGe         // Non-tail inlined 2-arg >=
	OpNumGeTail     // Tail inlined 2-arg >=
	OpNumEq         // Non-tail inlined 2-arg =
	OpNumEqTail     // Tail inlined 2-arg =
	OpCons          // Non-tail inlined cons
	OpConsTail      // Tail inlined cons
	OpMul           // Non-tail inlined 2-arg *
	OpMulTail       // Tail inlined 2-arg *
	OpDiv           // Non-tail inlined 2-arg /
	OpDivTail       // Tail inlined 2-arg /

	// Fallback: dispatch to sideTable[Arg]
	OpComplex
)

func (OpCode) String added in v1.4.0 

func (op OpCode) String() string

String returns the human-readable name of the opcode.

type OperandKind added in v1.10.7 

type OperandKind uint8

OperandKind classifies what an opcode's Arg field means. Used by cold-path consumers (Disassemble, instructionToOperation) to avoid re-deriving operand semantics in per-opcode switch branches. 

const (
	// OperandNone means Arg is unused (zero-operand ops).
	OperandNone OperandKind = iota
	// OperandRaw means Arg is a meaningful integer but needs no resolution
	// (e.g., PushEnv slot count, PeekK depth).
	OperandRaw
	// OperandLiteralIdx means Arg indexes into the literals pool.
	OperandLiteralIdx
	// OperandLocalIdx means Arg is a bit-packed (slot, depth) pair.
	OperandLocalIdx
	// OperandBranchOffset means Arg is a relative PC offset.
	OperandBranchOffset
	// OperandCachedBinding means Arg indexes into cachedBindings.
	OperandCachedBinding
	// OperandSideTable means Arg indexes into the side table.
	OperandSideTable
)

type Operation 

type Operation interface {
	values.Value
}

Operation is the base interface for all bytecode operations. Every operation is also a values.Value so it can appear in the literals pool and be printed. Operations that are inlined into the Run() switch loop only need this base interface. Operations dispatched through the side table (OpComplex) must additionally implement InlinedOperation.

type OperationApply 

type OperationApply struct {
	OperationBase
}

OperationApply is the bytecode operation that dispatches procedure calls. The compiler emits it after pushing arguments onto the eval stack and placing the callee in the value register. Apply pops all arguments and delegates to MachineContext.ApplyCallable, which handles the five callable types (MachineClosure, ForeignClosure, CaseLambdaClosure, Parameter, ComposableContinuation).

func NewOperationApply 

func NewOperationApply() *OperationApply

NewOperationApply returns a new apply operation.

func (*OperationApply) EqualTo 

func (p *OperationApply) EqualTo(o values.Value) bool

EqualTo returns true if o is also an OperationApply (identity by type).

type OperationBase added in v1.3.0 

type OperationBase struct {
	// contains filtered or unexported fields
}

OperationBase provides default SchemeString, IsVoid, and String methods for VM operations. Embed as the first field in operation structs. EqualTo is intentionally not provided: Go requires per-type assertions.

func NewOperationBase added in v1.3.0 

func NewOperationBase(opName string) OperationBase

NewOperationBase creates an OperationBase with the given Scheme name. The name is used as: "#<" + opName + ">".

func NewOperationBaseWithGoName added in v1.3.0 

func NewOperationBaseWithGoName(opName, goName string) OperationBase

NewOperationBaseWithGoName creates an OperationBase with both a Scheme name and a separate Go fmt.Stringer name.

func (OperationBase) IsVoid added in v1.3.0 

func (p OperationBase) IsVoid() bool

IsVoid returns false; operations are never void. Unlike other values.Value implementations, this does not handle nil receivers — operations are bytecode instructions constructed by the compiler and stored in NativeTemplate slices; they are never nil.

func (OperationBase) SchemeString added in v1.3.0 

func (p OperationBase) SchemeString() string

SchemeString returns the Scheme representation of the operation.

func (OperationBase) String added in v1.3.0 

func (p OperationBase) String() string

String returns the Go string representation of the operation.

type OperationBindPatternVars 

type OperationBindPatternVars struct {
	OperationBase
	PatternVars []string // Ordered list for consistent indexing
}

OperationBindPatternVars binds pattern variables from the last match into a new local environment frame that is pushed onto the current environment.

This operation creates a new environment frame with local slots for each pattern variable, binds the matched values, and makes this the current environment.

func NewOperationBindPatternVars 

func NewOperationBindPatternVars(patternVars map[string]struct{}) *OperationBindPatternVars

func (*OperationBindPatternVars) Apply 

func (p *OperationBindPatternVars) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationBindPatternVars) EqualTo 

func (p *OperationBindPatternVars) EqualTo(other values.Value) bool

type OperationBranchOffsetImmediate 

type OperationBranchOffsetImmediate struct {
	OperationBase
	Offset int
}

func NewOperationBranchOffsetImmediate 

func NewOperationBranchOffsetImmediate(offset int) *OperationBranchOffsetImmediate

func (*OperationBranchOffsetImmediate) EqualTo 

func (p *OperationBranchOffsetImmediate) EqualTo(o values.Value) bool

func (*OperationBranchOffsetImmediate) SchemeString 

func (p *OperationBranchOffsetImmediate) SchemeString() string

SchemeString overrides OperationBase to include offset value.

type OperationBranchOnFalseValueOffsetImmediate added in v1.4.0 

type OperationBranchOnFalseValueOffsetImmediate struct {
	OperationBase
	Offset int
}

OperationBranchOnFalseValueOffsetImmediate branches if the value register is #f. This reads directly from the value register instead of popping from the eval stack, eliminating the Push instruction that would otherwise be needed.

Peephole optimization (Aho et al., Compilers §8.9): examines a small window of generated instructions and replaces inefficient patterns. Here, the Push+BranchOnFalse+Pop sequence is replaced with a single BranchOnFalseValue that reads the value register directly. See BIBLIOGRAPHY.md "Peephole Optimization".

func NewOperationBranchOnFalseValueOffsetImmediate added in v1.4.0 

func NewOperationBranchOnFalseValueOffsetImmediate(offset int) *OperationBranchOnFalseValueOffsetImmediate

func (*OperationBranchOnFalseValueOffsetImmediate) EqualTo added in v1.4.0 

func (p *OperationBranchOnFalseValueOffsetImmediate) EqualTo(o values.Value) bool

func (*OperationBranchOnFalseValueOffsetImmediate) SchemeString added in v1.4.0 

func (p *OperationBranchOnFalseValueOffsetImmediate) SchemeString() string

SchemeString overrides OperationBase to include offset value.

type OperationBuildSyntaxList 

type OperationBuildSyntaxList struct {
	OperationBase
	Count int
}

OperationBuildSyntaxList builds a syntax list from elements on the eval stack. n elements are popped from the stack (in reverse order) and consed into a list.

func NewOperationBuildSyntaxList 

func NewOperationBuildSyntaxList(count int) *OperationBuildSyntaxList

NewOperationBuildSyntaxList creates a new OperationBuildSyntaxList.

func (*OperationBuildSyntaxList) Apply 

func (p *OperationBuildSyntaxList) Apply(mc *MachineContext) (*MachineContext, error)

Apply implements the Operation interface.

func (*OperationBuildSyntaxList) EqualTo 

func (p *OperationBuildSyntaxList) EqualTo(other values.Value) bool

type OperationClearSyntaxCaseInput 

type OperationClearSyntaxCaseInput struct {
	OperationBase
}

OperationClearSyntaxCaseInput clears the per-context syntax-case state. This is called at the end of a syntax-case form.

func NewOperationClearSyntaxCaseInput 

func NewOperationClearSyntaxCaseInput() *OperationClearSyntaxCaseInput

func (*OperationClearSyntaxCaseInput) Apply 

func (p *OperationClearSyntaxCaseInput) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationClearSyntaxCaseInput) EqualTo 

func (p *OperationClearSyntaxCaseInput) EqualTo(other values.Value) bool

type OperationDrop 

type OperationDrop struct {
	OperationBase
}

OperationDrop removes the top value from the eval stack without affecting the value register. This is used when we need to clean up the stack but preserve the current result.

func NewOperationDrop 

func NewOperationDrop() *OperationDrop

func (*OperationDrop) EqualTo 

func (p *OperationDrop) EqualTo(o values.Value) bool

type OperationForeignFunctionCall 

type OperationForeignFunctionCall struct {
	OperationBase
	Function ForeignFunction
}

OperationForeignFunctionCall executes a Go function within the VM loop. Used for foreign closures that do nested VM execution (sub-context + Run), where the iterative VM loop prevents Go stack growth. Leaf primitives use ForeignClosure + applyForeign instead.

func NewOperationForeignFunctionCall 

func NewOperationForeignFunctionCall(ffn ForeignFunction) *OperationForeignFunctionCall

func (*OperationForeignFunctionCall) Apply 

func (p *OperationForeignFunctionCall) Apply(mc *MachineContext) (rmc *MachineContext, rerr error)

func (*OperationForeignFunctionCall) EqualTo 

func (p *OperationForeignFunctionCall) EqualTo(o values.Value) bool

type OperationLoadCachedBinding added in v1.5.0 

type OperationLoadCachedBinding struct {
	OperationBase
	BindingIndex int32
}

OperationLoadCachedBinding loads a global variable from a compile-time resolved *Binding pointer, bypassing the runtime environment lookup path used by OpLoadGlobal.

func NewOperationLoadCachedBinding added in v1.5.0 

func NewOperationLoadCachedBinding(idx int32) *OperationLoadCachedBinding

NewOperationLoadCachedBinding creates a new cached binding load operation.

func (*OperationLoadCachedBinding) EqualTo added in v1.5.0 

func (p *OperationLoadCachedBinding) EqualTo(o values.Value) bool

EqualTo returns true if both operations have the same binding index.

func (*OperationLoadCachedBinding) SchemeString added in v1.5.0 

func (p *OperationLoadCachedBinding) SchemeString() string

SchemeString returns the Scheme representation of the operation.

type OperationLoadGlobalByGlobalIndexLiteralIndexImmediate 

type OperationLoadGlobalByGlobalIndexLiteralIndexImmediate struct {
	OperationBase
	LiteralIndex LiteralIndex
}

OperationLoadGlobalByGlobalIndexLiteralIndexImmediate loads a global variable using an index from the literals pool.

func NewOperationLoadGlobalByGlobalIndexLiteralIndexImmediate 

func NewOperationLoadGlobalByGlobalIndexLiteralIndexImmediate(li LiteralIndex) *OperationLoadGlobalByGlobalIndexLiteralIndexImmediate

NewOperationLoadGlobalByGlobalIndexLiteralIndexImmediate creates a new global load operation.

func (*OperationLoadGlobalByGlobalIndexLiteralIndexImmediate) EqualTo 

func (p *OperationLoadGlobalByGlobalIndexLiteralIndexImmediate) EqualTo(o values.Value) bool

EqualTo returns true if both operations have the same literal index.

func (*OperationLoadGlobalByGlobalIndexLiteralIndexImmediate) SchemeString 

func (p *OperationLoadGlobalByGlobalIndexLiteralIndexImmediate) SchemeString() string

SchemeString returns the Scheme representation of the operation.

type OperationLoadLiteralByLiteralIndexImmediate 

type OperationLoadLiteralByLiteralIndexImmediate struct {
	OperationBase
	LiteralIndex LiteralIndex
}

OperationLoadLiteralByLiteralIndexImmediate loads a literal value from the literals pool.

func NewOperationLoadLiteralByLiteralIndexImmediate 

func NewOperationLoadLiteralByLiteralIndexImmediate(li LiteralIndex) *OperationLoadLiteralByLiteralIndexImmediate

NewOperationLoadLiteralByLiteralIndexImmediate creates a new literal load operation.

func (*OperationLoadLiteralByLiteralIndexImmediate) EqualTo 

func (p *OperationLoadLiteralByLiteralIndexImmediate) EqualTo(o values.Value) bool

EqualTo returns true if both operations have the same literal index.

func (*OperationLoadLiteralByLiteralIndexImmediate) SchemeString 

func (p *OperationLoadLiteralByLiteralIndexImmediate) SchemeString() string

SchemeString returns the Scheme representation of the operation.

type OperationLoadLocalByLocalIndexImmediate 

type OperationLoadLocalByLocalIndexImmediate struct {
	OperationBase
	LocalIndex *environment.LocalIndex
}

func NewOperationLoadLocalByLocalIndexImmediate 

func NewOperationLoadLocalByLocalIndexImmediate(li *environment.LocalIndex) *OperationLoadLocalByLocalIndexImmediate

func (*OperationLoadLocalByLocalIndexImmediate) EqualTo 

func (p *OperationLoadLocalByLocalIndexImmediate) EqualTo(o values.Value) bool

func (*OperationLoadLocalByLocalIndexImmediate) SchemeString 

func (p *OperationLoadLocalByLocalIndexImmediate) SchemeString() string

type OperationLoadVoid 

type OperationLoadVoid struct {
	OperationBase
}

func NewOperationLoadVoid 

func NewOperationLoadVoid() *OperationLoadVoid

func (*OperationLoadVoid) EqualTo 

func (p *OperationLoadVoid) EqualTo(o values.Value) bool

type OperationMakeCaseLambdaClosure 

type OperationMakeCaseLambdaClosure struct {
	OperationBase
	// contains filtered or unexported fields
}

OperationMakeCaseLambdaClosure creates a case-lambda closure from multiple closures. Stack layout (top to bottom): closure_n, closure_n-1, ..., closure_1 The closureCount immediate specifies how many closures to pop.

func NewOperationMakeCaseLambdaClosure 

func NewOperationMakeCaseLambdaClosure(closureCount int) *OperationMakeCaseLambdaClosure

func (*OperationMakeCaseLambdaClosure) Apply 

func (p *OperationMakeCaseLambdaClosure) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationMakeCaseLambdaClosure) EqualTo 

func (p *OperationMakeCaseLambdaClosure) EqualTo(o values.Value) bool

type OperationMakeClosure 

type OperationMakeClosure struct {
	OperationBase
}

func NewOperationMakeClosure 

func NewOperationMakeClosure() *OperationMakeClosure

func (*OperationMakeClosure) Apply 

func (p *OperationMakeClosure) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationMakeClosure) EqualTo 

func (p *OperationMakeClosure) EqualTo(o values.Value) bool

type OperationPeekK 

type OperationPeekK struct {
	OperationBase
	Depth int
}

func NewOperationPeekK 

func NewOperationPeekK(depth int) *OperationPeekK

func (*OperationPeekK) EqualTo 

func (p *OperationPeekK) EqualTo(o values.Value) bool

func (*OperationPeekK) SchemeString 

func (p *OperationPeekK) SchemeString() string

SchemeString overrides OperationBase to include depth value.

type OperationPop 

type OperationPop struct {
	OperationBase
}

func NewOperationPop 

func NewOperationPop() *OperationPop

func (*OperationPop) EqualTo 

func (p *OperationPop) EqualTo(o values.Value) bool

type OperationPopEnv 

type OperationPopEnv struct {
	OperationBase
}

OperationPopEnv unconditionally restores the parent environment. It pops one level from the environment chain (restoring the parent environment).

This is used in syntax-case fender evaluation to restore the environment when the fender returns false, before branching to the next clause.

func NewOperationPopEnv 

func NewOperationPopEnv() *OperationPopEnv

func (*OperationPopEnv) EqualTo 

func (p *OperationPopEnv) EqualTo(other values.Value) bool

type OperationPopWind 

type OperationPopWind struct {
	OperationBase
}

OperationPopWind pops the innermost dynamic-wind frame from the winding stack. This operation does NOT call the after thunk - that is done explicitly in the bytecode stream to ensure proper continuation semantics.

The frame is simply removed from the winding stack. If a continuation captured inside the dynamic extent is later restored, the RestoreWithWinding mechanism will handle running the appropriate before/after thunks.

R7RS §6.10: dynamic-wind establishes a dynamic extent during which the before and after thunks are called whenever control enters or exits.

func NewOperationPopWind 

func NewOperationPopWind() *OperationPopWind

func (*OperationPopWind) Apply 

func (*OperationPopWind) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationPopWind) EqualTo 

func (p *OperationPopWind) EqualTo(o values.Value) bool

type OperationPull 

type OperationPull struct {
	OperationBase
}

func NewOperationPull 

func NewOperationPull() *OperationPull

func (*OperationPull) EqualTo 

func (p *OperationPull) EqualTo(o values.Value) bool

type OperationPush 

type OperationPush struct {
	OperationBase
}

func NewOperationPush 

func NewOperationPush() *OperationPush

func (*OperationPush) EqualTo 

func (p *OperationPush) EqualTo(o values.Value) bool

type OperationPushEnv added in v1.9.4 

type OperationPushEnv struct {
	OperationBase
	SlotCount int
}

OperationPushEnv allocates a new environment frame with the specified number of local binding slots and chains it to the current environment. Paired with OpPopEnv which restores the parent.

func NewOperationPushEnv added in v1.9.4 

func NewOperationPushEnv(slotCount int) *OperationPushEnv

func (*OperationPushEnv) EqualTo added in v1.9.4 

func (p *OperationPushEnv) EqualTo(other values.Value) bool

type OperationPushWind 

type OperationPushWind struct {
	OperationBase
}

OperationPushWind creates a dynamic-wind frame and pushes it onto the winding stack. It expects the stack to contain [before, thunk, after] where:

  • before is at PeekK(2) - the before thunk
  • thunk is at PeekK(1) - the main thunk (not used by this operation)
  • after is at PeekK(0) - the after thunk

The frame is created from the before and after closures and pushed onto the winding stack. The stack is not modified.

R7RS §6.10: dynamic-wind establishes a dynamic extent during which the before and after thunks are called whenever control enters or exits.

func NewOperationPushWind 

func NewOperationPushWind() *OperationPushWind

func (*OperationPushWind) Apply 

func (*OperationPushWind) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationPushWind) EqualTo 

func (p *OperationPushWind) EqualTo(o values.Value) bool

type OperationRestoreContMark added in v1.7.0 

type OperationRestoreContMark struct {
	OperationBase
}

OperationRestoreContMark restores the previous mark value after body evaluation. Paired with OperationSaveContMark.

Pre: eval stack = [..., key, old_val_or_sentinel] Post: eval stack = [...], marks[key] restored or deleted, pc++

func NewOperationRestoreContMark added in v1.7.0 

func NewOperationRestoreContMark() *OperationRestoreContMark

func (*OperationRestoreContMark) Apply added in v1.7.0 

func (*OperationRestoreContMark) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationRestoreContMark) EqualTo added in v1.7.0 

func (p *OperationRestoreContMark) EqualTo(o values.Value) bool

type OperationRestoreContinuation 

type OperationRestoreContinuation struct {
	OperationBase
}

func NewOperationRestoreContinuation 

func NewOperationRestoreContinuation() *OperationRestoreContinuation

func (*OperationRestoreContinuation) EqualTo 

func (p *OperationRestoreContinuation) EqualTo(o values.Value) bool

type OperationSaveContMark added in v1.7.0 

type OperationSaveContMark struct {
	OperationBase
}

OperationSaveContMark saves the previous mark value and sets a new one. Used in non-tail position, paired with OperationRestoreContMark.

Pre: eval stack = [..., key], value register = val Post: eval stack = [..., key, old_val_or_sentinel], marks[key] = val, pc++

func NewOperationSaveContMark added in v1.7.0 

func NewOperationSaveContMark() *OperationSaveContMark

func (*OperationSaveContMark) Apply added in v1.7.0 

func (*OperationSaveContMark) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSaveContMark) EqualTo added in v1.7.0 

func (p *OperationSaveContMark) EqualTo(o values.Value) bool

type OperationSaveContinuationOffsetImmediate 

type OperationSaveContinuationOffsetImmediate struct {
	OperationBase
	Offset int
}

func NewOperationSaveContinuationOffsetImmediate 

func NewOperationSaveContinuationOffsetImmediate(off int) *OperationSaveContinuationOffsetImmediate

func (*OperationSaveContinuationOffsetImmediate) EqualTo 

func (p *OperationSaveContinuationOffsetImmediate) EqualTo(o values.Value) bool

func (*OperationSaveContinuationOffsetImmediate) SchemeString 

func (p *OperationSaveContinuationOffsetImmediate) SchemeString() string

SchemeString overrides OperationBase to include offset value.

type OperationSetContMark added in v1.7.0 

type OperationSetContMark struct {
	OperationBase
}

OperationSetContMark sets a continuation mark on the current frame. Used in tail position where no restore is needed.

Pre: eval stack = [..., key], value register = val Post: eval stack = [...], marks[key] = val, pc++

func NewOperationSetContMark added in v1.7.0 

func NewOperationSetContMark() *OperationSetContMark

func (*OperationSetContMark) Apply added in v1.7.0 

func (*OperationSetContMark) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSetContMark) EqualTo added in v1.7.0 

func (p *OperationSetContMark) EqualTo(o values.Value) bool

type OperationStoreGlobalByGlobalIndexLiteralIndexImmediate 

type OperationStoreGlobalByGlobalIndexLiteralIndexImmediate struct {
	OperationBase
	LiteralIndex LiteralIndex
}

OperationStoreGlobalByGlobalIndexLiteralIndexImmediate stores a value to a global variable using an index from the literals pool.

func NewOperationStoreGlobalByGlobalIndexLiteralIndexImmediate 

func NewOperationStoreGlobalByGlobalIndexLiteralIndexImmediate(liti LiteralIndex) *OperationStoreGlobalByGlobalIndexLiteralIndexImmediate

NewOperationStoreGlobalByGlobalIndexLiteralIndexImmediate creates a new global store operation.

func (*OperationStoreGlobalByGlobalIndexLiteralIndexImmediate) EqualTo 

func (p *OperationStoreGlobalByGlobalIndexLiteralIndexImmediate) EqualTo(o values.Value) bool

func (*OperationStoreGlobalByGlobalIndexLiteralIndexImmediate) SchemeString 

func (p *OperationStoreGlobalByGlobalIndexLiteralIndexImmediate) SchemeString() string

SchemeString returns the Scheme representation of the operation.

type OperationStoreLocalByLocalIndexImmediate 

type OperationStoreLocalByLocalIndexImmediate struct {
	OperationBase
	LocalIndex *environment.LocalIndex
}

func NewOperationStoreLocalByLocalIndexImmediate 

func NewOperationStoreLocalByLocalIndexImmediate(li *environment.LocalIndex) *OperationStoreLocalByLocalIndexImmediate

func (*OperationStoreLocalByLocalIndexImmediate) EqualTo 

func (p *OperationStoreLocalByLocalIndexImmediate) EqualTo(o values.Value) bool

func (*OperationStoreLocalByLocalIndexImmediate) SchemeString 

func (p *OperationStoreLocalByLocalIndexImmediate) SchemeString() string

type OperationStoreSyntaxCaseInput 

type OperationStoreSyntaxCaseInput struct {
	OperationBase
}

OperationStoreSyntaxCaseInput stores the value register into the per-context syntaxCaseState for use by OperationSyntaxCaseMatch.

func NewOperationStoreSyntaxCaseInput 

func NewOperationStoreSyntaxCaseInput() *OperationStoreSyntaxCaseInput

func (*OperationStoreSyntaxCaseInput) Apply 

func (p *OperationStoreSyntaxCaseInput) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationStoreSyntaxCaseInput) EqualTo 

func (p *OperationStoreSyntaxCaseInput) EqualTo(other values.Value) bool

type OperationSyntaxCaseMatch 

type OperationSyntaxCaseMatch struct {
	OperationBase
}

OperationSyntaxCaseMatch performs pattern matching for syntax-case.

Expects:

  • Value register: syntaxCaseClause with compiled pattern
  • Per-context syntaxCaseState.input: input syntax object (set by OperationStoreSyntaxCaseInput)

Results:

  • If match succeeds: value register = #t, pattern bindings stored in context
  • If match fails: value register = #f

func NewOperationSyntaxCaseMatch 

func NewOperationSyntaxCaseMatch() *OperationSyntaxCaseMatch

func (*OperationSyntaxCaseMatch) Apply 

func (p *OperationSyntaxCaseMatch) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSyntaxCaseMatch) EqualTo 

func (p *OperationSyntaxCaseMatch) EqualTo(other values.Value) bool

type OperationSyntaxCaseNoMatch 

type OperationSyntaxCaseNoMatch struct {
	OperationBase
}

OperationSyntaxCaseNoMatch is emitted at the end of syntax-case when no clause matches.

func NewOperationSyntaxCaseNoMatch 

func NewOperationSyntaxCaseNoMatch() *OperationSyntaxCaseNoMatch

func (*OperationSyntaxCaseNoMatch) Apply 

func (p *OperationSyntaxCaseNoMatch) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSyntaxCaseNoMatch) EqualTo 

func (p *OperationSyntaxCaseNoMatch) EqualTo(other values.Value) bool

type OperationSyntaxRulesTransform 

type OperationSyntaxRulesTransform struct {
	OperationBase
}

OperationSyntaxRulesTransform is a VM operation that performs macro expansion.

Execution context:

  • Value register: contains clausesWrapper with compiled pattern/template pairs
  • Local parameter 0: contains the input form (the macro invocation)

The operation is part of the transformer closure created by CompileSyntaxRules.

func NewOperationSyntaxRulesTransform 

func NewOperationSyntaxRulesTransform() *OperationSyntaxRulesTransform

func (*OperationSyntaxRulesTransform) Apply 

func (p *OperationSyntaxRulesTransform) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSyntaxRulesTransform) EqualTo 

func (p *OperationSyntaxRulesTransform) EqualTo(other values.Value) bool

type OperationSyntaxTemplateExpand 

type OperationSyntaxTemplateExpand struct {
	OperationBase
}

OperationSyntaxTemplateExpand expands a syntax template using the current pattern variable bindings. This is used for templates containing ellipsis, which require runtime expansion rather than compile-time code generation.

The template is stored in the value register (loaded from literals). The result is the expanded syntax object, left in the value register.

func NewOperationSyntaxTemplateExpand 

func NewOperationSyntaxTemplateExpand() *OperationSyntaxTemplateExpand

func (*OperationSyntaxTemplateExpand) Apply 

func (p *OperationSyntaxTemplateExpand) Apply(mc *MachineContext) (*MachineContext, error)

func (*OperationSyntaxTemplateExpand) EqualTo 

func (p *OperationSyntaxTemplateExpand) EqualTo(other values.Value) bool

type OperationUnpackListToStack added in v1.5.0 

type OperationUnpackListToStack struct {
	OperationBase
}

OperationUnpackListToStack reads a proper list from the value register and pushes each element to the eval stack in order. Used by compiled (apply proc arg1 ... args) to flatten the final arg list onto the stack before Pull + OpApply.

Errors if the value is not a proper list (improper list or non-list).

func NewOperationUnpackListToStack added in v1.5.0 

func NewOperationUnpackListToStack() *OperationUnpackListToStack

NewOperationUnpackListToStack returns a new unpack-list-to-stack operation.

func (*OperationUnpackListToStack) EqualTo added in v1.5.0 

func (p *OperationUnpackListToStack) EqualTo(o values.Value) bool

EqualTo returns true if o is also an OperationUnpackListToStack (identity by type).

type Operations 

type Operations []Operation

func NewOperations 

func NewOperations(ops ...Operation) Operations

func (Operations) AsList 

func (p Operations) AsList() values.Tuple

func (Operations) Copy 

func (p Operations) Copy() Operations

func (Operations) EqualTo 

func (p Operations) EqualTo(o values.Value) bool

func (Operations) IsVoid 

func (p Operations) IsVoid() bool

func (Operations) Len 

func (p Operations) Len() int

func (Operations) SchemeString 

func (p Operations) SchemeString() string

type Parameter 

type Parameter struct {
	// contains filtered or unexported fields
}

Parameter represents an R7RS parameter object. Parameters are dynamically-scoped variables that can be temporarily rebound using parameterize. They act as procedures:

  • (param) returns the current value
  • (param val) sets the current value (after applying converter if present)

func NewParameter 

func NewParameter(init values.Value, converter Closure) *Parameter

NewParameter creates a new parameter with the given initial value and optional converter. The converter should be a procedure that takes one argument and returns the converted value. Pass nil for converter if no conversion is needed.

func (*Parameter) AcceptsArity added in v1.5.0 

func (p *Parameter) AcceptsArity(n int) bool

AcceptsArity reports whether this parameter can be called with n arguments. Parameters accept 0 args (get current value) or 1 arg (set value).

func (*Parameter) Converter 

func (p *Parameter) Converter() Closure

Converter returns the converter procedure, or nil if none.

func (*Parameter) EqualTo 

func (p *Parameter) EqualTo(v values.Value) bool

EqualTo uses identity comparison for parameters. Two parameters are equal only if they are the same object.

func (*Parameter) HasConverter 

func (p *Parameter) HasConverter() bool

HasConverter returns true if the parameter has a converter procedure.

func (*Parameter) IsVoid 

func (p *Parameter) IsVoid() bool

IsVoid returns true if the parameter is nil.

func (*Parameter) SchemeString 

func (p *Parameter) SchemeString() string

SchemeString returns the Scheme representation of the parameter.

func (*Parameter) SetValue 

func (p *Parameter) SetValue(v values.Value)

SetValue sets the current value of the parameter. Note: This does NOT apply the converter. The caller is responsible for converting the value before calling SetValue.

func (*Parameter) Value 

func (p *Parameter) Value() values.Value

Value returns the current value of the parameter.

type Pool added in v1.5.0 

type Pool[T any] struct {
	// contains filtered or unexported fields
}

Pool[T] is a type-safe, observable object pool backed by sync.Pool. It wraps sync.Pool with atomic counters (acquires, releases, misses) and an enable/disable toggle for debugging or benchmarking.

func NewPool added in v1.5.0 

func NewPool[T any](name string, newFn func() *T, resetFn func(*T)) *Pool[T]

NewPool creates a Pool[T] with the given name, constructor, and reset function. The pool starts enabled.

func (*Pool[T]) Acquire added in v1.5.0 

func (p *Pool[T]) Acquire() *T

Acquire returns an object from the pool. If the pool is disabled, it calls newFn directly (bypassing sync.Pool).

func (*Pool[T]) Drain added in v1.5.0 

func (p *Pool[T]) Drain()

Drain is a no-op on individual pools. Use PoolManager.DrainAll to trigger a GC-assisted drain across all pools.

func (*Pool[T]) Name added in v1.5.0 

func (p *Pool[T]) Name() string

Name returns the pool's name.

func (*Pool[T]) Release added in v1.5.0 

func (p *Pool[T]) Release(v *T)

Release resets the object and returns it to the pool. If the pool is disabled, the object is discarded after reset.

func (*Pool[T]) SetEnabled added in v1.5.0 

func (p *Pool[T]) SetEnabled(on bool)

SetEnabled toggles the pool on or off. When disabled, Acquire calls newFn directly and Release discards after reset, useful for benchmarking or debugging.

func (*Pool[T]) Stats added in v1.5.0 

func (p *Pool[T]) Stats() PoolSnapshot

Stats returns a point-in-time snapshot of the pool's counters.

type PoolHandle added in v1.5.0 

type PoolHandle interface {
	Name() string
	Stats() PoolSnapshot
	Drain()
	SetEnabled(bool)
}

PoolHandle is the type-erased interface that PoolManager uses to observe and control heterogeneous pools.

type PoolManager added in v1.5.0 

type PoolManager struct {
	// contains filtered or unexported fields
}

PoolManager tracks a collection of PoolHandle instances for unified observation and control.

func NewPoolManager added in v1.5.0 

func NewPoolManager() *PoolManager

NewPoolManager creates an empty PoolManager.

func (*PoolManager) AllStats added in v1.5.0 

func (p *PoolManager) AllStats() []PoolSnapshot

AllStats returns a snapshot of every registered pool's counters.

func (*PoolManager) DrainAll added in v1.5.0 

func (p *PoolManager) DrainAll()

DrainAll triggers a garbage collection, which clears all sync.Pool instances, then calls Drain on each registered pool.

func (*PoolManager) Register added in v1.5.0 

func (p *PoolManager) Register(h PoolHandle)

Register adds a pool to the manager.

func (*PoolManager) SetAllEnabled added in v1.5.0 

func (p *PoolManager) SetAllEnabled(on bool)

SetAllEnabled sets the enabled flag on every registered pool.

func (*PoolManager) String added in v1.5.0 

func (p *PoolManager) String() string

String returns a tabular summary of all registered pools.

type PoolSnapshot added in v1.5.0 

type PoolSnapshot struct {
	Name     string
	Acquires uint64
	Releases uint64
	Misses   uint64
	InFlight uint64
}

PoolSnapshot is a point-in-time view of a pool's counters.

type PromptTag 

type PromptTag struct {
	// contains filtered or unexported fields
}

PromptTag is an opaque identity value for delimited continuation prompts. Equality is pointer identity (each tag is unique). Follows the Racket model of continuation prompt tags.

See: Flatt, Yu, Findler, Felleisen "Adding Delimited and Composable Control to a Production Programming Environment" (ICFP 2007).

func NewPromptTag 

func NewPromptTag(name string) *PromptTag

NewPromptTag creates a new prompt tag with an optional name for debugging.

func (*PromptTag) EqualTo 

func (p *PromptTag) EqualTo(o values.Value) bool

func (*PromptTag) IsVoid 

func (p *PromptTag) IsVoid() bool

func (*PromptTag) SchemeString 

func (p *PromptTag) SchemeString() string

type SchemeError 

type SchemeError struct {
	Message    string
	Source     *syntax.SourceContext // Where error occurred
	StackTrace string                // Formatted stack trace
	Cause      error                 // Underlying error (if any)
}

SchemeError is a runtime error with Scheme-level stack trace.

func NewSchemeError 

func NewSchemeError(msg string, source *syntax.SourceContext, stackTrace string) *SchemeError

func NewSchemeErrorWithCause 

func NewSchemeErrorWithCause(msg string, source *syntax.SourceContext, stackTrace string, cause error) *SchemeError

func (*SchemeError) EqualTo 

func (p *SchemeError) EqualTo(o values.Value) bool

EqualTo compares for equality.

func (*SchemeError) Error 

func (p *SchemeError) Error() string

func (*SchemeError) IsVoid 

func (p *SchemeError) IsVoid() bool

IsVoid returns false (errors are not void).

func (*SchemeError) SchemeString 

func (p *SchemeError) SchemeString() string

SchemeString returns the Scheme representation.

func (*SchemeError) Unwrap 

func (p *SchemeError) Unwrap() error

type Stack 

type Stack values.Vector

func NewStack 

func NewStack(vs ...values.Value) *Stack

NewStack creates a new stack with the given initial values.

func (Stack) AsList 

func (p Stack) AsList() values.Tuple

AsList converts the stack to a Scheme list (values.Tuple). The list is in stack order (first pushed = first element).

func (*Stack) Clear 

func (p *Stack) Clear()

Clear removes all elements from the stack.

func (Stack) Copy 

func (p Stack) Copy() *Stack

Copy creates a shallow copy of the stack.

func (*Stack) Drain added in v1.5.0 

func (p *Stack) Drain() []values.Value

Drain returns a view of all stack elements and resets the stack to empty. The returned slice shares the stack's backing array — it is valid only until the next mutation (Push, PushAll, or any append). Callers must finish reading before any stack mutation.

Unlike PopAll (which copies into a new slice), Drain is zero-allocation. Use Drain when the caller consumes values immediately (e.g., binding arguments in Apply); use PopAll when the caller needs to own the slice.

func (Stack) IsVoid 

func (p Stack) IsVoid() bool

IsVoid returns true if the stack is nil.

func (Stack) Len 

func (p Stack) Len() int

Len returns the number of elements in the stack.

func (Stack) PeekK 

func (p Stack) PeekK(i int) values.Value

PeekK returns the kth value from the top of the stack without removing it. `K` is zero-based, so PeekK(0) returns the top value. `K` is used for methods that need a numeric index.

func (*Stack) Pop 

func (p *Stack) Pop() values.Value

Pop removes and returns the top value from the stack.

func (*Stack) PopAll 

func (p *Stack) PopAll() []values.Value

PopAll removes and returns all values from the stack. The caller gets exclusive ownership of the returned slice. The stack retains its backing array for reuse (avoids re-allocation on subsequent pushes). References in the retained portion are cleared so the GC can collect the values.

func (*Stack) PopN added in v1.4.0 

func (p *Stack) PopN(n int) []values.Value

PopN removes and returns the top n values from the stack. Values are returned in stack order (top-most element last). This is more efficient than calling Pop() n times.

func (*Stack) Pull 

func (p *Stack) Pull() values.Value

Pull removes and returns the bottom value from the stack. In the SECD model (Landin 1964), the procedure is evaluated first but needed last. Pull retrieves it from the bottom after all arguments have been pushed on top. See BIBLIOGRAPHY.md "Stack-Based Virtual Machines".

func (*Stack) PullDrain added in v1.10.5 

func (p *Stack) PullDrain() (values.Value, []values.Value)

PullDrain removes and returns the bottom value (position 0) as the first return, and all remaining values as the second return. The stack is cleared. This is O(1) — no element shifting, just slice header arithmetic.

The returned args slice shares the stack's backing array (same contract as Drain). Valid only until the next stack mutation.

func (*Stack) Push 

func (p *Stack) Push(v values.Value)

Push adds a value to the top of the stack.

func (*Stack) PushAll 

func (p *Stack) PushAll(vs []values.Value)

PushAll pushes all values from the slice onto the stack.

func (Stack) SchemeString 

func (p Stack) SchemeString() string

SchemeString returns a Scheme-like string representation of the stack.

func (Stack) String 

func (p Stack) String() string

String returns a string representation of the stack.

type StackFrame 

type StackFrame struct {
	FunctionName string                // Function name (or "<anonymous>")
	CallSite     *syntax.SourceContext // Where the call was made
	CurrentLoc   *syntax.SourceContext // Current execution point
}

StackFrame represents one frame in a Scheme stack trace.

func (*StackFrame) String 

func (p *StackFrame) String() string

String formats the frame for display.

type StackTrace 

type StackTrace []StackFrame

StackTrace is a list of stack frames.

func (StackTrace) String 

func (p StackTrace) String() string

String formats the entire stack trace.

type StepMode 

type StepMode int

StepMode represents the stepping mode for the debugger. 

const (
	StepNone StepMode = iota
	StepInto          // Step to next source location
	StepOver          // Step to next source location in same or parent frame
	StepOut           // Step until current frame returns
)

type SubContextParams added in v1.3.0 

type SubContextParams struct {
	Ctx              context.Context
	Env              *environment.EnvironmentFrame
	ParentMC         *MachineContext
	EscapeCont       *MachineContinuation
	ExceptionHandler *ExceptionHandler
	MaxCallDepth     uint64
	MaxStackSize     uint64
	WindingStack     WindingStack
}

SubContextParams holds the parent state needed to create a thread's sub-context. This is used to avoid race conditions when creating sub-contexts across goroutine boundaries.

type SyntaxCaseClause added in v1.10.5 

type SyntaxCaseClause struct {
	Bytecode       []match.SyntaxCommand
	PatternVars    map[string]struct{}
	EllipsisVars   map[int]map[string]struct{}
	EllipsisDepths map[int]int
}

SyntaxCaseClause wraps compiled pattern info for a syntax-case clause. Created by the compiler, consumed by OperationSyntaxCaseMatch at runtime.

func (*SyntaxCaseClause) EqualTo added in v1.10.5 

func (p *SyntaxCaseClause) EqualTo(other values.Value) bool

func (*SyntaxCaseClause) IsVoid added in v1.10.5 

func (p *SyntaxCaseClause) IsVoid() bool

func (*SyntaxCaseClause) SchemeString added in v1.10.5 

func (p *SyntaxCaseClause) SchemeString() string

type SyntaxRulesClause 

type SyntaxRulesClause struct {
	Template         syntax.SyntaxValue
	Bytecode         []match.SyntaxCommand
	Matcher          *match.SyntaxMatcher
	PatternVars      map[string]struct{}
	PatternVarSyntax map[string]*syntax.SyntaxSymbol
	EllipsisVars     map[int]map[string]struct{}
	FreeIds          map[string]*FreeIdResolution
	Ellipsis         string
	LiteralSyntax    map[string]*syntax.SyntaxSymbol
}

SyntaxRulesClause represents a single compiled pattern-template pair in a syntax-rules form. Created by the compiler, consumed by OperationSyntaxRulesTransform at runtime.

type VMCounters added in v1.1.0 

type VMCounters struct {
	OpsExecuted uint64

	ClosuresApplied        uint64
	EnvsCopied             uint64
	BindingsCopied         uint64
	ContinuationsSaved     uint64
	ContinuationsRestored  uint64
	StackDrains            uint64
	StackElementsDrained   uint64
	ForeignCalls           uint64
	SubContextsCreated     uint64
	StackPoolReleases      uint64
	SubContextPoolReleases uint64
	// Pool effectiveness under call/cc:
	//   ratio = SharedFrameRestores / (SharedFrameRestores + ContinuationPoolReleases)
	//   0.0 = no call/cc impact (all frames recycled via pool)
	//   1.0 = all frames shared (no recycling, pure GC pressure)
	//   > 0.5 = pool losing more than it saves; consider profiling GC pauses
	ContinuationPoolReleases uint64
	EnvFramePoolReleases     uint64
	SharedFrameRestores      uint64
	KeysShared               uint64
	InlineEvalsSaved         uint64 // SaveContinuation used inline slots instead of stack pool

	// Stack depth instrumentation (ongoing monitoring; prior cap-tuning investigation
	// showed cap-8 is sufficient for observed workloads)
	StackMaxDepth   uint64
	StackDepth0to2  uint64 // depth 0-2: fits trivially
	StackDepth3to4  uint64 // depth 3-4: typical calls
	StackDepth5to8  uint64 // depth 5-8: fits in pool cap 8
	StackDepth9to16 uint64 // depth 9-16: requires 1 growth from cap 8
	StackDepth17p   uint64 // depth 17+: requires 2+ growths
	// contains filtered or unexported fields
}

VMCounters holds performance counters for a single MachineContext execution. All counters are plain uint64 — no atomics needed because each MachineContext is single-goroutine. Sub-contexts have their own counters (not aggregated into the parent).

func (VMCounters) CallHistogram added in v1.7.0 

func (p VMCounters) CallHistogram() string

CallHistogram returns a formatted histogram of per-callee call counts (both foreign primitives and named Scheme procedures), sorted by frequency (descending). Returns empty string when profiling is disabled.

func (VMCounters) OpcodeHistogram added in v1.6.0 

func (p VMCounters) OpcodeHistogram() string

OpcodeHistogram returns a formatted histogram of opcode hit counts, sorted by frequency (descending). Only opcodes with non-zero hits are included.

func (*VMCounters) RecordCall added in v1.7.0 

func (p *VMCounters) RecordCall(name string)

RecordCall increments the call count for the named callee (foreign primitive or Scheme-defined procedure). No-op when profiling is disabled (nil map).

func (*VMCounters) RecordStackDepth added in v1.4.0 

func (p *VMCounters) RecordStackDepth(n int)

RecordStackDepth updates the depth histogram and max tracker.

func (VMCounters) String added in v1.1.0 

func (p VMCounters) String() string

String returns a tabular summary of all counters.

type WindingStack 

type WindingStack []*DynamicWindFrame

WindingStack tracks the current dynamic-wind context. It's a slice of frames from outermost to innermost.

func (WindingStack) Copy 

func (p WindingStack) Copy() WindingStack

Copy creates a shallow copy of the winding stack.

func (WindingStack) Depth 

func (p WindingStack) Depth() int

Depth returns the number of active dynamic-wind frames.

func (*WindingStack) Pop 

func (p *WindingStack) Pop() *DynamicWindFrame

Pop removes the innermost frame from the winding stack.

func (*WindingStack) Push 

func (p *WindingStack) Push(frame *DynamicWindFrame)

Push adds a frame to the winding stack.

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