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
See opam file for version constraints.
base64, 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
opam install js_of_ocaml js_of_ocaml-ppx
Makefile.confto change the default configuration
make allto compile
make installas root to install the compiler
and its libraries
make uninstallas root to uninstall them
You can run
make toplevel-examples if you want to build a Web-based OCaml
toplevel as well. Try the toplevel
Your program must first be compiled using the OCaml bytecode compiler
The syntax extension is provided by
ocamlfind ocamlc -package js_of_ocaml -package js_of_ocaml.ppx -linkpkg -o cubes.byte cubes.ml
Then, run the
Most of the OCaml standard library is supported. However,
A dummy implementation is provided.
Most of the Sys module is not supported.
Extra libraries distributed with Ocaml (such as Thread or Str) are not
supported in general. However,
Bigarray: bigarrays are supported using Typed Arrays
Num: supported using
Graphics: partially supported using canvas (see js_of_ocaml.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.
Data representation differs from the usual one. Most notably,
integers are 32 bits (rather than 31 bits or 63 bits), which is their
consequence, marshalling, polymorphic comparison, and hashing
functions can yield results different from usual:
marshalling of floats is not supported (unmarshalling works);
the polymorphic hash function will not give the same results on
datastructures containing floats;
these functions may be more prone to stack overflow.
Ocaml 4.04.2 includes Base, Core_kernel, Async_kernel, Async_js
Ocaml 4.04.0+BER see http://okmij.org/ftp/ML/MetaOCaml.html
Ocaml 4.05.0 includes Base, Core_kernel, Async_kernel, Async_js
Ocaml 4.06.0 includes Base, Core_kernel, Async_kernel, Async_js
Contents of the distribution
| Filename | Description |
| LICENSE | license and copyright notice |
| README | this file |
| compiler/ | compiler |
| examples/ | small examples |
| ppx/ | ppx syntax extensions |
| camlp4/ | camlp4 syntax extensions |
| runtime/ | runtime system |
| toplevel/ | web-based OCaml toplevel |
| ocamlbuild/ | ocamlbuild plugin for js_of_ocaml |
>= "2.4.4" & < "5.0.0"