OCaml-Zig-FFI

Table of Contents

• Overview
• Architecture
• Installation
• Usage
  • Using Ctypes
  • Low-Level External Declarations
• Building Zig Libraries for OCaml
• Type Mappings
• Examples
• RSR Compliance
• License

OCaml bindings for calling Zig libraries via FFI.

Overview

This library provides type-safe OCaml bindings to Zig libraries. Zig exports C-compatible functions that OCaml can call through its C FFI mechanism using ctypes or external declarations.

Architecture

OCaml → Ctypes → Zig (C ABI)

Using the ctypes library for high-level, type-safe FFI.

Installation

opam install ocaml-zig-ffi

Or add to your dune-project:

(depends
  (ocaml-zig-ffi (>= 0.1)))

Usage

Using Ctypes

open Zig_ffi

(* Load the library *)
let lib = Zig_ffi.load "./libmyzig.so"

(* Call functions *)
let result = Zig_ffi.add lib 2 3
(* result = 5 *)

Low-Level External Declarations

external add : int -> int -> int = "zig_add"
external multiply : int -> int -> int = "zig_multiply"

Building Zig Libraries for OCaml

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

OCaml Type	Zig Type	Ctypes Type
int	i32 / i64	int
int32	i32	int32_t
int64	i64	int64_t
float	f64	double
string	[*:0]const u8	string
bytes	[*]u8	ocaml_bytes

Examples

See the examples/ directory for complete working examples.

RSR Compliance

This library follows the Rhodium Standard Repository guidelines:

• OCaml for AffineScript compiler

• Zig for performance-critical FFI

• No C wrapper code required

License

PMPL-1.0-or-later