package js_of_ocaml

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Compiler from OCaml bytecode to JavaScript

Install

Dune Dependency

Authors

Maintainers

Sources

js_of_ocaml-6.0.1.tbz
sha256=813dbee2b62e1541049ea23a20e405cf244e27ebfa9859785cfa53e286d2c614
sha512=194ae5d1122171fa8253b6a41438a2fc330caf4ab6dd008fcce1253fd51fbe4b1149813da6075c5deb52ea136143def57c83c3f4e32421803d7699648fdc563b

Description

Js_of_ocaml is a compiler from OCaml bytecode to JavaScript. It makes it possible to run pure OCaml programs in JavaScript environment like browsers and Node.js

Published: 13 Feb 2025

README

Js_of_ocaml (jsoo)

Js_of_ocaml is a compiler from OCaml bytecode to JavaScript. It makes it possible to run pure OCaml programs in JavaScript environment like browsers and Node.js.

  • It is easy to install and use as it works with an existing installation of OCaml, with no need to recompile any library.

  • It comes with bindings for a large part of the browser APIs.

  • According to our benchmarks, the generated programs runs typically faster than with the OCaml bytecode interpreter.

  • We believe this compiler will prove much easier to maintain than a retargeted OCaml compiler, as the bytecode provides a very stable API.

Js_of_ocaml is composed of multiple packages:

  • js_of_ocaml-compiler, the compiler.

  • js_of_ocaml-ppx, a ppx syntax extension.

  • js_of_ocaml, the base library.

  • js_of_ocaml-ppx_deriving_json

  • js_of_ocaml-lwt, lwt support.

  • js_of_ocaml-tyxml, tyxml support.

  • js_of_ocaml-toplevel, lib and tools to build an ocaml toplevel to javascript.

  • wasm_of_ocaml-compiler, the Wasm_of_ocaml compiler.

Requirements

See opam file for version constraints.

Supported engines

The generated code works with Node.js 16 or any recent web-browser compatible with ECMAScript 6. We optionally rely on js WeakRef, which is part of ECMAScript 2021, to implement Stdlib.Weak and Stdlib.Ephemeron.

Toplevel requirements

  • tyxml, reactiveData

  • ocp-indent: needed to support indentation in the toplevel

  • higlo: needed to support Syntax highlighting in the toplevel

  • cohttp: needed to build the toplevel webserver

Installation

Opam

opam install js_of_ocaml js_of_ocaml-compiler js_of_ocaml-ppx

Usage

Your program must first be compiled using the OCaml bytecode compiler ocamlc. JavaScript bindings are provided by the js_of_ocaml package. The syntax extension is provided by js_of_ocaml-ppx package.

ocamlfind ocamlc -package js_of_ocaml -package js_of_ocaml-ppx -linkpkg -o cubes.byte cubes.ml

Then, run the js_of_ocaml compiler to produce JavaScript code:

js_of_ocaml cubes.byte

Features

Most of the OCaml standard library is supported. However,

  • Most of the Sys module is not supported.

Extra libraries distributed with OCaml (such as Thread) are not supported in general. However,

  • Bigarray: bigarrays are supported using Typed Arrays

  • Num: supported

  • Str: supported

  • Graphics: partially supported using canvas (see js_of_ocaml-lwt.graphics)

  • Unix: time related functions are supported

Tail call is not optimized in general. However, mutually recursive functions are optimized:

  • self recursive functions (when the tail calls are the function itself) are compiled using a loop.

  • trampolines are used otherwise. More about tail call optimization.

Effect handlers are supported with the --effects={cps,double-translation} flag.

Data representation

Data representation differs from the usual one. Most notably, integers are 32 bits (rather than 31 bits or 63 bits), which is their natural size in JavaScript, and floats are not boxed. As a consequence, marshalling, polymorphic comparison, and hashing functions can yield results different from usual:

  • marshalling floats might generate different output. Such output should not be unmarshalled using the standard ocaml runtime (native or bytecode).

  • the polymorphic hash function will not give the same results on datastructures containing floats;

  • these functions may be more prone to stack overflow.

OCaml javascript
int number (32bit int)
int32 number (32bit int)
nativeint number (32bit int)
int64 Object (MlInt64)
float number
string string or object (MlBytes)
bytes object (MlBytes)
"immediate" (e.g. true, false, None, ()) number (32bit int)
"block" array with tag as first element (e.g. C(1,2) => [tag,1,2])
array block with tag 0 (e.g. [\|1;2\|] => [0,1,2])
tuple block with tag 0 (e.g. (1,2) => [0,1,2])
record block (e.g. {x=1;y=2} => [0,1,2])
constructor with arguments block (e.g. C (1, 2) => [tag,1,2])
module block
exception and extensible variant block or immediate
function function

Toplevel

Contents of the distribution

Filename Description
LICENSE license and copyright notice
README this file
compiler/ compiler
examples/ small examples
lib/ library for interfacing with JavaScript APIs
ppx/ ppx syntax extensions
runtime/ runtime system
toplevel/ web-based OCaml toplevel

Dependencies (4)

  1. ppxlib >= "0.15"
  2. js_of_ocaml-compiler = version
  3. ocaml >= "4.08"
  4. dune >= "3.17"

Dev Dependencies (4)

  1. odoc with-doc
  2. re >= "1.9.0" & with-test
  3. ppx_expect >= "v0.14.2" & with-test
  4. num with-test

Used by (94)

  1. alba >= "0.4.1"
  2. archetype >= "1.2.7"
  3. async_js >= "v0.13.0" & < "v0.15.0"
  4. binaryen >= "0.3.0" & < "0.12.1"
  5. bls12-381-js
  6. bls12-381-js-gen
  7. bonsai >= "v0.15.1" & < "v0.17.0"
  8. brisk-reconciler
  9. brr = "0.0.3"
  10. brr-lwd
  11. chartjs
  12. chartjs-annotation
  13. chartjs-colorschemes
  14. chartjs-datalabels
  15. chartjs-streaming
  16. cohttp-lwt-jsoo >= "2.5.0"
  17. cordova
  18. cordova-plugin-background-mode
  19. cordova-plugin-battery-status
  20. cordova-plugin-local-notifications
  21. cordova-plugin-sim-card
  22. dream >= "1.0.0~alpha5"
  23. dune >= "3.17.0"
  24. eliom >= "6.9.2" & < "6.10.1" | >= "7.0.0" & < "10.4.0"
  25. ezjs_ace
  26. ezjs_blockies < "0.1.1"
  27. ezjs_cleave
  28. ezjs_d3pie
  29. ezjs_extension >= "0.2"
  30. ezjs_fetch < "0.2"
  31. ezjs_min < "0.2"
  32. ezjs_odometer
  33. ezjs_push < "0.2"
  34. ezjs_qrcode
  35. ezjs_recaptcha
  36. ezjs_timeline
  37. fmlib_js >= "0.5.11"
  38. gen_js_api < "1.0.7"
  39. github-jsoo < "4.1.0"
  40. graphv_font_js
  41. incr_dom_interactive != "v0.15.0" & < "v0.17.0"
  42. incr_dom_keyboard
  43. incr_dom_partial_render != "v0.15.0" & < "v0.17.0"
  44. incr_dom_sexp_form != "v0.15.0" & < "v0.17.0"
  45. incr_dom_widgets
  46. integers_stubs_js
  47. irmin-indexeddb
  48. joolog
  49. js_of_ocaml-lwt >= "6.0.1"
  50. js_of_ocaml-ppx >= "6.0.1"
  51. js_of_ocaml-ppx_deriving_json >= "6.0.1"
  52. js_of_ocaml-tyxml >= "6.0.1"
  53. js_of_ocaml-webgpu
  54. js_of_ocaml-webidl
  55. js_of_ocaml_patches < "v0.17.0"
  56. json-data-encoding-browser
  57. jsonoo
  58. jsoo-react
  59. jsoo_broadcastchannel
  60. kkmarkdown
  61. landmarks >= "1.5"
  62. ldp_js
  63. leaflet
  64. learn-ocaml
  65. liquidsoap-js
  66. lp-glpk-js
  67. multicore-magic >= "2.3.1"
  68. nanoid
  69. node_of_ocaml
  70. nuscr < "1.1.0"
  71. ocp_reveal
  72. ocplib-json-typed-browser
  73. ocsigen-start != "2.15.1" & < "2.16.0" | >= "7.1.0"
  74. ojs_base >= "0.8.0"
  75. plotly
  76. polynomial >= "0.4.0"
  77. ppx_css >= "v0.15.1" & < "v0.17.0"
  78. ppx_jsobject_conv != "0.9.3"
  79. promise_jsoo
  80. prr
  81. rpclib-js
  82. sherlodoc
  83. spin >= "0.8.0"
  84. tezt >= "3.1.0"
  85. timedesc-tzlocal-js
  86. timmy-jsoo >= "1.1.5"
  87. tyxml-lwd >= "0.2"
  88. virtual_dom < "v0.15.0"
  89. wasm_of_ocaml-compiler
  90. webtest-js
  91. wikitext
  92. xmldiff_js
  93. xtmpl = "0.18.0"
  94. xtmpl_js

Conflicts

None

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