lx

lx: Controllable AI for Gophers!

lx restores the joy of wrangling code by letting you define the forest, while AI plants the trees under your intentional command.

Table of Contents

• Philosophy
• Why lx?
• Example
• Usage
• Configuration
• Dependency Management
• Installation
• License

Philosophy

Some argue that Vibe Coding is just a natural evolution like the shift from punch cards to Assembly, and then to C. I fundamentally disagree. Historical abstractions were about placing a better hammer in the developer's hand. The tools evolved, but the wielder remained human. The outcome was always under our absolute control. Today's Vibe Coding is different. The robot has taken the hammer. We’ve been sidelined, left to do nothing but beg the machine for the right output. If we do not wield the hammer, we are no longer makers. If it is not under our control, it's not programming anymore. That is why I built lx. lx puts the hammer back in the Gopher's hand, restoring absolute control. It allows you to command AI strictly on your terms through a new paradigm: LLM Functionalization. It all works in your editor, on your machine, under your terms.

Why lx?

1. Developer Sovereignty

The function signature is the contract. lx treats your function names, parameters, and return types as an immutable contract. AI cannot change your architecture; it can only fulfill the implementation details you demand.

2. Deterministic AI Coding

lx doesn't just read your code. It runs it. If your function is not called during execution, lx does nothing. It strictly adheres to the Go runtime path. No hallucinations for dead code, no assumptions about unused functions. Through Trace & Patch, lx replaces probabilistic guesswork with runtime facts.

3. Continuous Development

With lx, once you write a function’s inputs and outputs, you can keep moving as if the logic is already there. But it’s not “design-only” — your program still has to compile and run. You drive the flow and the contract; lx uses runtime traces to fill in the function internals.

4. Freedom of Editor

VS Code? Vim? Zed? Cursor? It doesn't matter. lx is a CLI tool. It works where you work.

5. Smart Generation

lx is efficient and safe. Once a function is implemented, lx remembers it. It will never overwrite your existing logic, unless you explicitly delete the body. You can run lx a thousand times without fear.

6. Hierarchical Configuration

lx follows strict precedence: Local config (project) overrides Global config (home). It adapts to your workspace, not the other way around.

Example

Test code

package main

import (
	"fmt"

	"github.com/chebread/lx"
)

func main() {
	var message = "happ"
	fmt.Println(LX_Func1(message + "y"))
	fmt.Println("-----------------------")
	var isTrue = LX_Func2("홍")
	if isTrue {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}

func LX_Func1(a string) string {
	lx.Gen(fmt.Sprintf("I am %s", a))
	var x = "bar"
	return x
}

func LX_Func2(k string) bool {
	lx.Gen(fmt.Sprintf("Determine if current system seconds are odd (true) or even (false). Use time package. Input %s name is mandatory per contract but unused in logic.", k+"길동"))
	var foo bool = false
	return !foo
}

Generated code

package main

import (
	"fmt"
	"time"
)

func main() {
	var message = "happ"
	fmt.Println(LX_Func1(message + "y"))

	fmt.Println("-----------------------")

	var isTrue = LX_Func2("홍길동")
	if isTrue {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}

func LX_Func1(a string) string {
	// lx-prompt: I am happy

	// lx-dep: fmt
	x := fmt.Sprintf("I am %s", a)
	return x
}

func LX_Func2(k string) bool {
	// lx-prompt: Determine if current system seconds are odd (true) or even (false). Use time package. Input 홍길동 name is mandatory per contract but unused in logic.

	// lx-dep: time
	return time.Now().Second()%2 != 0
}

Terminal results

$ lx --show-stdout .

[lx] Start running...
[lx] Config: ~/lx-config.yaml [Global]
[lx] Provider: [gemini] / Model: [gemini-3-flash-preview]
[lx] Converting code
[lx] Run the program and collect data
	[INPUT] LX_Func1: lx-prompt: I am happy
	[OUTPUT] LX_Func1: I am happy
	[capture stdout] I am happy
	[capture stdout] -----------------------
	[capture stdout] No
[lx] Restore the source code
[lx] Analyze the collected data and generating code
	[Data] LX_Func1: Input="lx-prompt: I am happy", Output=Confirmed
[lx] [/Users/ihaneum/work/lx/test/test.go -> LX_Func1] Generate code
[lx] [/Users/ihaneum/work/lx/test/test.go -> LX_Func1] code generation failed
[lx] Error: You have exceeded your API call quota. Please try again later or check your payment information.
[lx] All tasks completed

$ go run .
I am happy
-----------------------
Yes

Usage

You only need three things:

1. Input: function params (real runtime values)
2. Intent: lx.Gen(...) (your instruction)
3. Output: return type + dummy return (the expected shape)

lx operates strictly at function scope. It will rewrite the function body, but it will not change your function signature.

Note: lx executes your program during capture. Any runtime side effects in your code will happen.

Step 1: Write the contract

// test.go
package main

import (
	"fmt"

	"github.com/chebread/lx"
)

func main() {
	// You own the flow.
	fmt.Println(LX_Greeter("Gopher", true))
}

func LX_Greeter(name string, isMorning bool) string {
	// Intent: describe the logic. (captured at runtime)
	lx.Gen(fmt.Sprintf("Greet %s politely. Is it morning? %v", name, isMorning))

	// Output: dummy return that matches the real output shape.
	return "Dummy Greeting String"
}

Step 2: Run lx

lx only generates code for functions that are actually reached during execution. If LX_Greeter is never called in main(), lx will assume it is dead code and skip it.

lx [flags...] [PATH]

• PATH can be . (project root), a relative path, or an absolute path.
• If omitted, lx defaults to the current directory (.).

Capture Mode (LX_MODE=capture)

During the capture run, lx sets:

• LX_MODE=capture

This is intentional: it lets you explicitly control side effects during capture. If your program does anything risky (network calls, DB writes, file operations), guard it:

if os.Getenv("LX_MODE") == "capture" {
    // capture run: keep it safe and quiet
    // (no network calls, no DB writes, no destructive operations)
}

What lx [PATH] does

1. Injects spies into target functions (wraps returns with lx.Spy(...))
2. Runs go run . inside the target directory to capture real inputs and expected outputs
3. Reverts the injected spies immediately (restores your source files)
4. Generates and patches the function bodies based on the captured evidence

Useful flags (optional)

• -timeout=2m: stop capture if your program doesn’t exit
• -show-stdout=true: show your program’s stdout (trace lines excluded)
• -max-prompt, -max-context, -max-output: bound what gets sent to the LLM

Step 3: Review the result

func LX_Greeter(name string, isMorning bool) string {
	// lx-prompt: Greet Gopher politely. Is it morning? true
	// lx-dep: fmt

	if isMorning {
		return fmt.Sprintf("Good morning, %s! Hope you have a productive day.", name)
	}
	return fmt.Sprintf("Good evening, %s. Time to rest.", name)
}

Configuration

Create an lx-config.yaml file in your home directory (~/) or project root.

provider: "gemini"
api_key: "YOUR_API_KEY"
model: "foo_bar" 

[!NOTE] Currently, only Google Gemini is supported.

Dependency Management

lx respects the Single Responsibility Principle(SRP). It generates code, but it doesn't silently install packages. If the AI uses a new library (e.g., github.com/google/uuid), lx will:

1. Add // lx-dep: ... comments in the code.
2. Report any issues to the terminal.

Installation

To use lx, you need both the CLI tool and the Go library. Here is the straightforward setup for any Gopher.

1. Install the CLI

lx is deployed via Homebrew for macOS.

brew tap chebread/lx
brew install lx

[!NOTE] Currently, only macOS (Intel/Apple Silicon) is supported.

2. Add the Library to your Project

Add the dependency to your project to use lx.Gen() in your code.

go get github.com/chebread/lx

License

This project is licensed under the AGPL-3.0 License.