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1.0.4000 • Public • Published


This is Cmdliner, a CLI-interface building tool for OCaml, packaged for BuckleScript (an OCaml-to-JavaScript compiler) and Reason (an alternative OCaml syntax targeting that compiler.)

You can safely ignore the installation instructions below when compiling to JS. Instead:

  1. If you're writing an app or a similar end-consumer project, install BuckleScript compiler (a peerDependency of this project) via npm.

    $ npm install --save bs-platform

    Worh repeating: do not add this dependency to a library! The final application-developer should generally select the version of the BuckleScript compiler; you don't want users having duplicated versions of the compiler in their node_modules. Instead, library developers should add bs-platform to both "peerDependencies" (with a permissive version), and "devDependencies" (with a restrictive version):

    $ npm install --save-dev bs-platform
     "devDependencies": {
       "bs-platform": "^5.0.0"
     "peerDependencies": {
    +  "bs-platform": "4.x || 5.x" // example. express the versions of BuckleScript you support here.
  2. Install bs-cmdliner as a runtime-dependency.

    npm install --save @elliottcable/bs-cmdliner
  3. Manually add bs-cmdliner to your bsconfig.json's bs-dependencies:

    "bs-dependencies": [
  4. Write a CLI!

The usage docs are below, but one thing worth noting, is that Node.js doesn't follow the POSIX standard for argv; so you need to prepend process.argv.shift() or similar to actually executing your command-line interface. Something like this should do:

(* OCaml syntax *)
open Cmdliner
[%%raw "process.argv.shift()"]
let hello () = print_endline "Hello, world!"
let hello_t = Term.(const hello $ const ())
let () = Term.exit @@ Term.eval (hello_t, Term.info "wrange")
/* ReasonML syntax */
open Cmdliner;
%raw "process.argv.shift()";
let hello = () => print_endline("Hello, world!");
let hello_t = Term.(const(hello) $ const());
let () = Term.exit @@ Term.eval((hello_t, Term.info("wrange")));

Versioning of this package

Thanks to SemVer not including a ‘generation’ number, there's really no way I can reasonably tie this project's version on npm to the upstream version of Cmdliner as released to opam by Daniel. As ugly as it is, I've opted to pin the major version of bs-cmdliner, to the flattened major and minor versions of the upstream project.

This means that the ported versions would look something like this:

cmdliner (opam) bs-cmdliner (npm)
v1.0.2 v10.2.x
v1.0.4 v10.4.x

(I'm applying this scheme as of bs-cmdliner v10.2.1.)

Correspondingly, this project can't really strictly adhere to SemVer; I have no control over the major/minor components of bs-cmdliner's published versions, and thus must compress breaking changes to the npm port into the patch-component. /=

NOTE: OCaml doesn't often move fast; and I can't say I have much intention to follow the upstream development of Cmdliner with a microscope. As of right now, BuckleScript (4.02.3) is pretty far behind upstream OCaml (4.08.0); and while there's a beta-release of a slightly-less-vastly-outdated version of BuckleScript out there (specifically, 4.06.1), it hasn't reached maturity yet.

As upstream Cmdliner has dropped support for 4.02.3; and BuckleScript's 4.06.1 release hasn't reached stability yet, I'm opting to not publish newer versions of Cmdliner to npm yet — this includes, as of this writing, Cmdliner 1.0.3 and 1.0.4.

If this affects you, and you are on 4.06.1 already, feel free to reach out directly if you want me to bump the version on npm. No promises, though, if substantial changes to the source are necessary to make it compile. (There's a reason I didn't stomp on the npm package names outside my own scope! ;))

Original README follows:

Cmdliner — Declarative definition of command line interfaces for OCaml


Cmdliner allows the declarative definition of command line interfaces for OCaml.

It provides a simple and compositional mechanism to convert command line arguments to OCaml values and pass them to your functions. The module automatically handles syntax errors, help messages and UNIX man page generation. It supports programs with single or multiple commands and respects most of the POSIX and GNU conventions.

Cmdliner has no dependencies and is distributed under the ISC license.

Home page: http://erratique.ch/software/cmdliner
Contact: Daniel Bünzli <daniel.buenzl i@erratique.ch>


Cmdliner can be installed with opam:

opam install cmdliner

If you don't use opam consult the opam file for build instructions.


The documentation and API reference is automatically generated by from the source interfaces. It can be consulted online or via odig doc cmdliner.

Sample programs

If you installed Cmdliner with opam sample programs are located in the directory opam config var cmdliner:doc. These programs define the command line of some classic programs.

In the distribution sample programs are located in the test directory of the distribution. They can be built and run with:

topkg build --tests true && topkg test


npm i @prometheansacrifice/bs-cmdliner

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