image:[License,link="https://github.com/hyperpolymath/palimpsest-license"]

ReScript-Zig-FFI

ReScript bindings for calling Zig libraries via the C ABI.

Overview

This library provides a type-safe way to call Zig code from ReScript. Zig exports C-compatible functions that ReScript can call through its external mechanism.

Architecture

ReScript → External Declarations → Deno FFI → Zig (C ABI)

ReScript compiles to JavaScript running in Deno, which uses Deno.dlopen to load Zig shared libraries.

Installation

# Add to your deno.json
{
  "imports": {
    "@hyperpolymath/rescript-zig-ffi": "jsr:@hyperpolymath/rescript-zig-ffi@0.1"
  }
}

Usage

Defining External Functions

// src/bindings/MyZigLib.res

@module("./ffi.js")
external zigFunction: (int, int) => int = "zigFunction"

@module("./ffi.js")
external zigStringOp: string => string = "zigStringOp"

JavaScript FFI Layer

// src/ffi.js
const lib = Deno.dlopen("./libmyzig.so", {
  zigFunction: { parameters: ["i32", "i32"], result: "i32" },
  zigStringOp: { parameters: ["pointer"], result: "pointer" }
});

export const zigFunction = lib.symbols.zigFunction;

Building Zig Libraries for ReScript

Your Zig code must export C-compatible functions:

// mylib.zig
export fn add(a: i32, b: i32) callconv(.C) i32 {
    return a + b;
}

Build as shared library:

zig build-lib -dynamic -O ReleaseFast mylib.zig

Type Mappings

ReScript Type	Zig Type	Notes
int	i32	32-bit signed integer
float	f64	64-bit float
bool	bool	Boolean
string	[*:0]const u8	Null-terminated string
array<'a>	[*]T	Pointer to array

Examples

See the examples/ directory for complete working examples.

RSR Compliance

This library follows the Rhodium Standard Repository guidelines:

• ReScript for all application code

• Deno for runtime and package management

• Zig for FFI implementation

• No C code required

License

AGPL-3.0-or-later