README

README.md

ctypes is a library for binding to C libraries using pure OCaml. The primary aim is to make writing C extensions as straightforward as possible.

The core of ctypes is a set of combinators for describing the structure of C types -- numeric types, arrays, pointers, structs, unions and functions. You can use these combinators to describe the types of the functions that you want to call, then bind directly to those functions -- all without writing or generating any C!

Usage

Suppose you want to bind to the following C functions:

   int sigemptyset(sigset_t *set);   int sigfillset(sigset_t *set);   int sigaddset(sigset_t *set, int signum);   int sigdelset(sigset_t *set, int signum);   int sigismember(const sigset_t *set, int signum);

Using ctypes you can describe the interfaces to these functions as follows:

   let sigemptyset = foreign "sigemptyset" (ptr sigset_t @-> returning int)   let sigfillset = foreign "sigfillset" (ptr sigset_t @-> returning int)   let sigaddset = foreign "sigaddset" (ptr sigset_t @-> int @-> returning int)   let sigdelset = foreign "sigdelset" (ptr sigset_t @-> int @-> returning int)   let sigismember = foreign "sigismember" (ptr sigset_t @-> int @-> returning int)

The names bound by this code have the types you might expect:

   val sigemptyset : sigset_t ptr -> int   val sigfillset : sigset_t ptr -> int   val sigaddset : sigset_t ptr -> int -> int   val sigdelset : sigset_t ptr -> int -> int   val sigismember : sigset_t ptr -> int -> int

That's all there is to it. Unlike theusual way of writing C extensions, there are no C "stub" functions to write, so there's much less opportunity for error.

The documentation and source distribution contain more complex examples, involving structs, unions, arrays, callback functions, and so on, and show how to create and use C values (like instances ofsigset_t ptr) in OCaml.

Links

• Building C libraries in OCaml with the dune ctypes stanza describes how to use ctypes withdune

• Chapter 19: Foreign Function Interface ofReal World OCaml describes ctypes

• Modular Foreign Function Bindings introduces ctypes in the context of theMirage library operating system

• Tutorial

• API documentation

• Mailing list

• Type-safe C bindings using ocaml-ctypes and stub generation introduces theCstubs interface

• Using Cstubs_structs shows how to use theCstubs_structs module to reliably determine data layout

• A modular foreign function interface is a research paper (extending anearlier paper) that presents the design of ctypes

• FAQ

1. conf-libffi>= "2.0.0"
2. conf-pkg-config
3. dune-configurator
4. ctypes= version
5. ocaml>= "4.03.0"
6. dune>= "2.9"

1. odocwith-doc
2. conf-ftswith-test & os != "win32"
3. stdlib-shimswith-test
4. conf-ncurseswith-test
5. ounit2with-test
6. lwtwith-test & >= "2.4.7"
7. integerswith-test & >= "0.2.2"

1. argon2
2. arrayjit
3. async_ssl
4. bimage-unix
5. bls12-381= "0.3.15"
6. bls12-381-legacy< "0.4.4"
7. bls12-381-unix< "1.0.2"
8. camlkit-base
9. cf
10. checked_oint< "0.4.1"
11. cmark
12. cmarker
13. corosync
14. ctypes< "0.21.1"
15. ctypes-zarith
16. cudajit
17. directories< "0.3"
18. extism
19. flock
20. gccjit
21. gdal
22. gobject-introspection
23. gpiod
24. gr
25. guile
26. hacl-star-raw< "0.4.4"
27. hardcaml_c
28. hardcaml_verilator
29. hdr_histogram
30. imguiml
31. libbpf_maps
32. libdash
33. libirmin
34. libudev
35. lilv
36. llama-cpp-ocaml
37. lmdb< "1.0"
38. lp-glpk< "0.4.0"
39. lp-gurobi
40. memtrace_viewer< "v0.15.0"
41. mmdb
42. mpg123
43. netlink
44. ocephes
45. octez-l2-libs
46. opasswd
47. opencc< "transition"
48. opencc0
49. opencc1
50. opencc1_1
51. orocksdb
52. osx-cf
53. osx-secure-transport
54. pari
55. pari-bindings
56. pg_query
57. pkcs11-driver
58. pkcs11-rev
59. portaudio_c_bindings
60. portmidi
61. posix-getopt< "2.0.0"
62. py
63. qcstm>= "0.1.1"
64. reed-solomon-erasure
65. sarek
66. sattools
67. sodium< "0.6.0"
68. spoc
69. srt>= "0.2.2"
70. stk_iconv
71. swipl
72. tensorflow
73. tezos-wasmer
74. tgls
75. torch
76. tsdl
77. tsdl-image
78. tsdl-mixer
79. tsdl-ttf
80. unix-type-representations< "0.1.1"
81. wasmer
82. wasmtime
83. yara
84. yices2_bindings

None