Portable Foreign Function Interface for R7RS schemes

An attempt to make basic foreign function interface that is supported on multiple R7RS Sceheme implementations.

Pull requests to fix bugs and add more tests are welcome.

Goals

• Support only R7RS implementations
  • Needs to have cond-expand and library support atleast (propably much more)
• 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 support all R7RS implementations
• To have every possible FFI feature
• Compiling of C code at any point
  • That is no stubs, no C code generated by the library and so on

For bugs you can use the Bugs

All tests (there is not that many yet) pass

• Sagittarius
• Guile
• Kawa
• Needs atleast java 21
• Needs jvm flags
  • java --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 --enable-preview -jar kawa.jar FILENAME.scm
• Racket
• Chicken

Not all tests pass

• STKlos
• Cyclone
• Gambit

Support waiting for the implementation

• LIPS
  • Waiting for implementation to have cond-expand and library support
  • Will only work on nodejs

Not supported

• Chibi
• FFI requires C code
• MIT-Scheme
• FF requires C code
• tr7
• FFI requires C code
• Gauche
• FFI requires C code

Hacking

main.sld is the real main which is copied to main.scm

Documentation

On some implementations these are procedures, on some macros.

Types

Types are given as symbols, for example 'int8 or 'pointer.

• int8
• uint8
• int16
• uint16
• int32
• uint32
• int64
• uint64
• char
• unsigned-char
• short
• unsigned-short
• int
• unsigned-int
• long
• unsigned-long
• float
• double
• string
• pointer

Procedures or macros

pffi-shared-object-auto-load

Arguments:

• object-name (symbol)
  • The name of the dynamic library file you want to load without the "lib" in fron of it or .so/.dll at the end
• addition-paths (list (string)...)
  • Any additional paths you want to search for the library

Returns:

• (object) Shared object, the type depends on the implementation

pffi-shared-object-load

It is recommended to use the pffi-shared-object-auto-load instead of this directly.

Arguments:

• headers (list (string) ...) Headers that need to be included
• Example (list "curl/curl.h")
• path (string) The full path to the shared object you want to load, including any "lib" infront and .so/.dll at the end
• Example "libcurl.so"

Returns:

• (object) Shared object, the type depends on the implementation

pffi-define

Defines new foreign procedure.

Arguments:

• scheme-name () The name of the procedure used on scheme side
• shared-object (object) The shared object
• Use pffi-shared-object-auto-load and pffi-shared-object-load to get this
• c-name (symbol) The name of the C function
• return-type (symbol) The return type of the C function
• arguments-types (list (symbol) ...) The C function argument types