This library uses Template Haskell and language-c-quote, a quasi-quotation library for C-like languages, to provide inline C and Objective-C in Haskell. It extracts the C/Objective-C code automatically, when compiling the Haskell program, and generates marshalling code for common types. The wiki on GitHub details the motivation for this approach.

For further motivation, you might like to watch the YouTube video (matching slides) of my talk at the Haskell Symposium 2014 (Gothenburg, Sweden), or look at the slides of my YOW! Lambda Jam 2014 talk Foreign Inline Code in Haskell.

To build the library, just use cabal install as usual from the source code directory or by installing from Hackage.

You may like to have a look at a minimal example of its use, which you can build as follows:

• Execute cd tests/objc/minimal; make.
• Now run the demo executable with ./Minimal.

To build the proof of concept example, do the following:

• Execute cd tests/objc/concept; make.
• Now run the demo executable with ./InlineObjC.

To build an example class wrapping a Haskell record, do the following:

• Execute cd tests/objc/record; make.
• Now run the demo executable with ./Particle.

To build the more complex Haskell interpreter app:

• Execute cd tests/objc/app; make.
• Now open -a HSApp.app.

Update: For various reasons (mostly lack of time on my side), all my recent changes have been on the release/0.7 branch, which also hosts the version that you can find on Hackage. That version has been used in production. It is the glue between the Haskell and Swift part of Haskell for Mac. For a larger open-source example of using language-c-inline, see HaskellSpriteKit.

Unfortunately, I haven't been able to find the time to merge all the improvements on release/0.7 back into master.

The library is in beta and focuses mostly on Objective-C. Automatic marshalling support is still somewhat limited. However, it is quite easy to add more types, and I do welcome pull request!