Goon

A tiny embeddable configuration language with Nix-like syntax.

• ~1800 lines of C - zero dependencies
• 39KB binary - smaller than most config parsers
• JSON output - integrates with anything
• Arrow functions - define your own config templates

Quick Example

let key = (mods, key, cmd) => { mods = mods; key = key; cmd = cmd; };

let keys = map([1..9], (n) => key("super", n, "workspace ${n}"));

{
    border_width = 2;
    gap = 10;
    keys = keys;
}

Output:

{
  "border_width": 2,
  "gap": 10,
  "keys": [
    { "mods": "super", "key": 1, "cmd": "workspace 1" },
    { "mods": "super", "key": 2, "cmd": "workspace 2" },
    ...
  ]
}

Features

• Let bindings: let x = 1;
• Records: { name = "foo"; value = 42; }
• Lists: [1, 2, 3]
• Ranges: [1..9] expands to [1, 2, 3, 4, 5, 6, 7, 8, 9]
• Arrow functions: (x) => { doubled = x; }
• String interpolation: "value is ${x}"
• Spread operator: { ...defaults; custom = 1; }
• Imports: import("./other.goon")
• Conditionals: if cond then a else b or cond ? a : b

Why C? Because C has the best C interop.

Requires only a C99 compiler.

Embedding

Copy src/goon.c and src/goon.h into your project.

#include "goon.h"

int main() {
    Goon_Ctx *ctx = goon_create();

    if (!goon_load_file(ctx, "config.goon")) {
        goon_error_print(goon_get_error_info(ctx));
        goon_destroy(ctx);
        return 1;
    }

    Goon_Value *result = goon_eval_result(ctx);

    // Access fields
    Goon_Value *name = goon_record_get(result, "name");
    if (goon_is_string(name)) {
        printf("name: %s\n", goon_to_string(name));
    }
// Or convert to JSON
    char *json = goon_to_json_pretty(result, 2);
    printf("%s\n", json);
    free(json);

    goon_destroy(ctx);
    return 0;
}

Registering Custom Functions

Goon_Value *my_func(Goon_Ctx *ctx, Goon_Value **args, size_t argc) {
    if (argc < 1 || !goon_is_int(args[0])) return goon_nil(ctx);
    return goon_int(ctx, goon_to_int(args[0]) * 2);
}

Goon_Ctx *ctx = goon_create();
goon_register(ctx, "double", my_func);

Why Goon?

Use goon for configs.

Documentation

• SPEC.md - Language specification
• examples/ - Example configs