gen_js_api: easy OCaml bindings for JavaScript libraries

Overview

gen_js_api aims at simplifying the creation of OCaml bindings for JavaScript libraries. It must currently be used with the js_of_ocaml compiler, although other ways to run OCaml code "against" JavaScript might be supported later with the same binding definitions (for instance, Bucklescript, or direct embedding of a JS engine in a native OCaml application).

gen_js_api is based on the following ideas:

• Authors of bindings write OCaml signatures for JavaScript libraries and the tool generates the actual binding code with a combination of implicit conventions and explicit annotations.

• The generated binding code takes care of translating values between OCaml and JavaScript and of dealing with JavaScript calling conventions.

• All syntactic processing is done by authors of bindings: the client code is normal OCaml code and does not depend on custom syntax nor on JS-specific types.

gen_js_api can be used in two complementary ways:

• Generating .ml implementations from annotated .mli interfaces, in order to create the code for stub libraries.

• As a ppx preprocessor on implementations to define local bindings.

Examples

The repository contains some examples of OCaml bindings to JavaScript libraries created with gen_js_api:

• Very partial bindings to jQuery, with some example client code.

• Partial bindings to JavaScript strings and regexps and JavaScript dates.

• Some ad hoc test to exercise various features.

• An example of a self-contained program, a simple calculator, implementing local .bindings

Documentation

• Install and use
• Low-level binding to JavaScript
• Using gen_js_api to generate .ml from .mli
• Using gen_js_api as a ppx processor
• Default naming convention
• JS-able types and type declarations
• Value bindings
• Class-wrapping bindings
• TODO list

Related projects

• js_of_ocaml: The compiler and runtime system on which gen_js_api relies. (Note: gen_js_api doesn't depend on js_of_ocaml's OCaml library, nor on its language extension.)

• goji: A DSL to describe OCaml bindings for JavaScript libraries.

• DefinitelyMaybeTyped: A project to parse DefinitelyTyped interfaces and produce OCaml interfaces.

• ReScript: Another compiler from OCaml to JavaScript, featuring the genType ppx for generating TS / Flow types and runtime converters.

About

gen_js_api has been created by LexiFi for porting a web application from JavaScript to OCaml. The tool has been used in production since 2015.

This gen_js_api package is licensed by LexiFi under the terms of the MIT license.

See see Changelog

Contact: alain.frisch@lexifi.com

Contributors:

• Alain Frisch
• Sebastien Briais