config.ml

Ergonomic, lightweight conditional compilation through attributes inspired by Rust's cfg macro.

Config implements the [@@config] annotation, to conditionally compile modules. You can use a small boolean language to check for conditions including some built-in ones and environment variables.

Currently includes/detects the following platforms:

• Windows 32/64
• macOS/tvOS/watchOS/iOS
• FreeBSD/NetBSD
• Android
• Linux

And the following architectures:

• x86-64
• x86 i386
• aarch64
• arm

Getting Started

opam install config

And add it to your dune files:

(library
  (name my_lib)
  (preprocess (pps config.ppx)))

And tag your modules with the @@config attribute:

module A = A_unix [@@config any(target_os = "macos", target_os = "linux")]
module A = A_win32 [@@config any(target_os = "windows")]

Contributing

Currently config relies on C preprocessor definitions to detect different platforms and architectures. They are straightforward to add by extending the file ./config/config_stubs.cl. In there :

• To add a new platform, extend the main if-else chain in the caml_config_target_os function to include your OS.

• To add a new architecture, extend the main if-else chain in the caml_config_target_arch function to include your architecture.