# Portable Foreign Function Interface for R7RS schemes

Foreign function interface that is supported on multiple R7RS Sceheme implementations.

Note that this software is in **alpha** stage. That said the interface should not be changing anymore.

Any help in form of constructive advice and bug reports are appreciated.

[Documentation](https://retropikzel.neocities.org/r7rs-pffi/) or run mkdocs serve or see docs/.

[Issue trackers](https://sr.ht/~retropikzel/r7rs-pffi/trackers)

[Maling lists](https://sr.ht/~retropikzel/r7rs-pffi/lists)

For documentation see [retropikzel.neocities.org/r7rs-pffi](retropikzel.neocities.org/r7rs-pffi)
or run mkdocs serve or see or docs/ directory.

For status of what tests pass on which implementations see
[Jenkins](https://jenkins.staging.scheme.org/job/r7rs-pffi/job/master/).

## Goals

- Support only R7RS implementations
- Same interface on all implementations
  - Some things that are procedures on one implementation are macros on other,
  but they must behave the same

## Non goals

- To have every possible FFI feature
- Compiling of used library C code at any point
    - That is no stubs, no C code generated by the library and so on
    - The pffi library itself may require compilation on installation

## Known issues that are worked on

- Passing struct does not work on Chicken
    - For example [SDL2-ttf TTF_RenderUTF8_Solid](https://wiki.libsdl.org/SDL2_ttf/TTF_RenderUTF8_Solid)
    wants the color to be passed as struct.
    - Not a problem on Guile, Sagittarius or Racket
    - Cyclone status unknown, assumed same as Chicken

## Status

Currently the interface of the library is in okay shape. It propably will not change much but no
guarantees are being made just yet.

### Usable

- [Guile](https://www.gnu.org/software/guile/)
- [Sagittarius](https://bitbucket.org/ktakashi/sagittarius-scheme/wiki/Home)
- [Chicken 5](https://www.call-cc.org/)
    - Needs [r7rs egg](https://wiki.call-cc.org/eggref/5/r7rs)
- [Racket](https://racket-lang.org/)
    - Needs [racket-r7rs](https://github.com/lexi-lambda/racket-r7rs)

### Work in progress

- [Cyclone](https://justinethier.github.io/cyclone/)
    - TODO
        - pffi-define-callback
        - pffi-pointer-address
        - pffi-pointer-dereference
- [STKlos](https://stklos.net/)
- [Kawa](https://www.gnu.org/software/kawa/index.html)
    - TODO
        - pffi-define-callback
        - pffi-pointer-address
        - pffi-pointer-dereference
- [STKlos](https://stklos.net/)
    - Needs at least java version 22
    - Needs jvm flags:
        - --add-exports java.base/jdk.internal.foreign.abi=ALL-UNNAMED
        - --add-exports java.base/jdk.internal.foreign.layout=ALL-UNNAMED
        - --add-exports java.base/jdk.internal.foreign=ALL-UNNAMED
        - --enable-native-access=ALL-UNNAMED
- [STKlos](https://stklos.net/)
- [Mosh](https://mosh.monaos.org)
    - TODO
        - pffi-pointer-address
        - pffi-pointer-dereference
- [STKlos](https://stklos.net/)

### Design/exploration

- [Gambit](https://gambitscheme.org)
- [LIPS](https://lips.js.org/)
    - Will work on nodejs by using some Javascript FFI
    - Javascript side needs design
- [Biwascheme](https://www.biwascheme.org/)
    - Will work on nodejs by using some Javascript FFI
    - Javascript side needs design
- [Chibi](https://synthcode.com/scheme/chibi)
- [MIT-Scheme](https://www.gnu.org/software/mit-scheme/)
- [tr7](https://gitlab.com/jobol/tr7)
- [Gauche](https://practical-scheme.net/gauche/)
- [s7](https://scheme.fail://ccrma.stanford.edu/software/snd/snd/s7.html)
- [Gerbil](https://cons.io/)
    - Should be possible as built on gambit, but makes sense to make gambit support first
- [Ypsilon](http://www.littlewingpinball.com/doc/en/ypsilon/)
- [Larceny](https://larcenists.org/)
- [Skint](https://github.com/false-schemers/skint)
- [Airship](https://gitlab.com/mbabich/airship-scheme)
- [Other gambit targets](https://gambitscheme.org/)
  - Gambit compiles to different targets other than C too, for example Javascript. It would be cool
  and interesting to see if this FFI could also support some of those
- [s48-r7rs](https://codeberg.org/prescheme/s48-r7rs)
- [prescheme](https://codeberg.org/prescheme/prescheme)

### Will/can not be supported

- [Loko](https://scheme.fail/)
    - Desires no C interop, I can respect that