c

c

A stack-based calculator REPL, ported from Mancalc to Go with readline and expr support.

go install github.com/kensmith/c@latest
c

Enter each value, expression, or RPN operator on its own line. The prompt shows the stack from bottom to top; the rightmost value is the top.

Stack operations

Numeric operators consume their operands and push their results. Unary operators replace the top value; binary operators replace the top two values, preserving any values below them. Multi-result operators such as frexp consume one operand and put their first result on top.

All six reducers return 0 for an empty stack. var and sd calculate sample variance and standard deviation, and return 0 for a singleton stack. The four predicates require an operand; underflow leaves the empty stack unchanged. isinf tests positive infinity, isninf tests negative infinity, and signbit also recognizes negative zero.

For example, enter these four lines on an empty stack:

1
2
3
sum

The resulting stack is [ 6 ].

Constants such as pi and the random generator r push a value without consuming anything. rn consumes its upper bound. Stack commands perform their named actions: pop removes the top value, swap exchanges the top two, sort reorders the stack, and clear empties it. f prints the stack and noop leaves it alone.

Expressions

Expressions read a snapshot of the stack: s[0] is the top value, s[1] is the next value down, and so on. Evaluating an expression pushes its numeric result without consuming existing values. For example, starting with an empty stack:

2
3
s[0] + s[1]

The resulting stack is [ 2 3 5 ]. Likewise, sum(s) preserves its inputs, while the standalone RPN command sum consumes them.

See the quality review and follow-up plan for remaining correctness and maintenance work.