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sigil-ffi

Dynamic Foreign Function Interface for Sigil.

Call C library functions from Sigil at runtime without writing glue code. Built on a vendored dyncall, which provides portable calling conventions including struct-by-value passing on every supported arch (x86_64, aarch64, arm32, riscv, mips, ppc, sparc, s390, …).

Modules

Module	Purpose
`(sigil ffi)`	Library load, symbol lookup, call, structs, callbacks

API summary

Procedure	Purpose
`c-library`	Open a shared library by name
`c-library-close`	Close a previously opened library
`c-symbol`	Resolve a symbol in a library
`c-function`	Bind a function with arg-types and ret-type
`define-c-library`	Convenience macro for binding many functions
`c-sizeof` / `c-alignof`	Query size/alignment of an FFI type
`make-pointer` / `pointer-address`	Build/read raw pointer values
`pointer-ref` / `pointer-set!`	Dereference a pointer at a typed offset
`string->pointer` / `pointer->string`	String/pointer round-trip
`pointer->bytevector` / `bytevector->pointer`	Bytevector bridge
`c-alloc` / `c-free` / `with-c-alloc`	Manual memory
`c-errno` / `c-strerror`	errno + strerror access
`c-struct-layout` / `c-struct-ref` / `c-struct-set!`	Struct field access
`c-struct->dict` / `dict->c-struct`	Struct/dict marshalling
`c-callback` / `c-callback-release`	Bind a Scheme procedure as a C callback

FFI type constants: ffi/void, ffi/bool, ffi/int8..ffi/uint64, ffi/float, ffi/double, ffi/pointer, ffi/string, plus arch-relative ffi/int, ffi/uint, ffi/long, ffi/ulong, ffi/size-t.

Read the rest

System prerequisites

A working C toolchain. dyncall is vendored under vendor/dyncall/ and compiled in-tree; no system libdyncall required. Your platform must be one dyncall supports — see vendor/dyncall/dyncall/README* for the arch matrix.

Dependencies

sigil-stdlib

Build

sigil deps install
sigil build
sigil test --report

The first build compiles dyncall + dyncallback (vendor/dyncall/) plus native/ffi.c. Subsequent builds hit the cache.

Usage

(import (sigil ffi))

(define libm (c-library "libm"))
(define cbrt (c-function libm "cbrt" (list ffi/double) ffi/double))
(cbrt 27.0)                               ; => 3.0

(define libc (c-library "libc"))
(define getenv (c-function libc "getenv" (list ffi/string) ffi/string))
(getenv "HOME")                           ; => "/home/you"

define-c-library collapses the bind-many-functions pattern:

(import (sigil ffi))

(define-c-library libm "libm"
  (cbrt  (ffi/double) ffi/double)
  (sqrt  (ffi/double) ffi/double)
  (pow   (ffi/double ffi/double) ffi/double))

(cbrt 27.0)                               ; => 3.0
(pow 2.0 10.0)                            ; => 1024.0

License

BSD-3-Clause.

Vendored dyncall (under vendor/dyncall/) is distributed under a permissive ISC-style license — see vendor/dyncall/LICENSE. sigil-ffi's own sources are BSD-3-Clause.

Clone

$ git clone https://codeberg.org/sigil/sigil-ffi

Releases

v0.16.3 — latest by version, released 15 Jul 2026

All releases — 6 tags in this repository.

Source

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Recent commitsAtom

1 Augcommit

Add docket repo descriptor, and declare the vendored tree excluded

dc85b58d