8
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MIT
unpublishedBindings to BuckleScript compiler

bs-in-a-box

The BuckleScript compiler stuffed into a neatly wrapped box with a bow on top, for embedding into BuckleScript apps.

Or, all-in-one BuckleScript compiler compiled to JavaScript, including the standard library and BuckleScript/Reason bindings

Installation

Run npm install --save glennsl/bs-in-a-box and add bs-in-a-box to the bs-dependencies in bsconfig.json.

Example

  • RE
  • ML
[@bs.val] external eval : string => 'a = "";

let code  = {|
  let hello thing =
    Js.log {j|Hello $thing!|j}

  let () =
    hello "world"
|};

let result =
  BsBox.compile(code);

switch result {
| Ok({ code })       => eval(code);
| Error({ message }) => Js.log2("Error: ", message)
};
external eval : string -> 'a = ""[@@bs.val ]
let code =
  {|
  let hello thing =
    Js.log {j|Hello $thing!|j}

  let () =
    hello "world"
|}
let result = BsBox.compile code
let _ =
  match result with
  | ((Ok ({ code }))[@explicit_arity ]) -> eval code
  | ((Error ({ message }))[@explicit_arity ]) -> Js.log2 "Error: " message

Usage

Compiling and running code that does not use the standard library can be as simple as the example above. But you should be aware that the compiler is not modular, but instead attaches itself to window.ocaml or global.ocaml and can be interferred with by other code.

Standard Library

If you want to use the standard library it gets a bit more complicated. This package includes a standard library bundle that must be evaluated in the context the compiled code will be run in. This is because the compiler will emit require calls, and the standard library bundle includes a require polyfill/override that knows about the standard library modules.

In a browser context it is sufficient to include the bundle in a script tag:

<script src="node_modules/bs-in-a-box/vendor/stdlibBundle.js"></script>

In case you don't want to include all of node_modules in your production build, you can use webpacks file-loader to copy the file to your build directory. This is the setup rebench uses, in webpack.config.js:

...
module: {
  loaders: [{
    test: /\.(png|jpg|gif|html|css)$|stdlibBundle.js$/,
    loader: 'file-loader?name=[name].[ext]'
  }],
},
...

Then in a web worker (written in JavaScript):

require('../node_modules/bs-in-a-box/vendor/stdlibBundle.js');
importScripts('stdlibBundle.js');

If you use a script tag, you should put the require in your entry point module. If it's in Reason, just put this at the top:

  • RE
  • ML
[%%raw "require('../node_modules/bs-in-a-box/vendor/stdlibBundle.js')"];
[%%raw "require('../node_modules/bs-in-a-box/vendor/stdlibBundle.js')"]

Then the script tag might look like this, depending on what your output directory is:

<script src="build/stdlibBundle.js"></script>

In a node context you can read it in as a text file and then evaluate it using vm.runInContext or a similar function. See the node_sandbox example for details.

This package does not contain the Reason preprocessor (refmt). For bindings to that, see bs-refmt

Bundling

The compiler has been tested to work with webpack, but requires a tiny bit of configuration because it depends on a few ndoe modules in code paths that aren't actually used in practice. To stub these out, just put the following in your webpack.config.js:

  node: {
    fs: 'empty',
    child_process: 'empty'
  }

Load external modules

Using external modules requires two components, the type information to use at compile-time, and the js-compiled module to use at runtime.

Compile-time

The type information will be retrieved from the .cmi and .cmj compilation artifacts, which needs to be encoded using scripts/bin2js.js and then loaded into the compiler using BsBox.loadModule:

  • RE
  • ML
BsBox.loadModule(
  ~name="MyExternal",
  ~cmi=[%raw {|"Caml1999I017\x84\x95\xa6\xbe\0\0\0f\0\0\0\x19\0\0\0V\0\0\0Q\xa0*MyExternal\xa0\xa0\xb0\x01\x03\xf3%hello@\xc0\xb0\xc1 \xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfc\xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfd@\x02\x05\xf5\xe1\0\0\xfe@\xb0\xc0&_none_A@\0\xff\x04\x02A@@\x84\x95\xa6\xbe\0\0\0\xf3\0\0\0(\0\0\0\x90\0\0\0w\xa0\xa0*MyExternal\x900\x02LzF\xe5\xf4\xb2\xdc|\xa1\xf5\xde3\xe4\xdf\"\xa0\xa0&String\x900e\x90\x7f\x1d\xde\xc3+\xe4\xc8\xa1\x90\x07\x91p\xe0\xf1\xa0\xa0*Pervasives\x900\r\x01ZZ!6e\x9b\r\xe41\xbe\x7f\x15E\xbe\xa0\xa0)Js_string\x900GV\xce|\x10H7Ib\x80\x9b\xb5F\".u\xa0\xa0%Js_re\x9006s\xb2X\x9a=\x93\xf6=\x05#\0\xa2\r\xd3f\xa0\xa0(Js_array\x900\x92\x1e\xbe\x88=\x94\xf1y@\x9d\x98\xefN\xd6\xdc\x0f\xa0\xa0\"Js\x900\xd3g\x87\x88u\xa2\xf2\xe6\x1b\xad\xa9\xc5\x81\x85lF\xa0\xa08CamlinternalFormatBasics\x900\x8b\x06\x9f\xca\x1eM\x93\x16\xb5\x88\xe5UO8\xbb$@\x84\x95\xa6\xbe\0\0\0\x01\0\0\0\0\0\0\0\0\0\0\0\0@%"|}],
  ~cmj=[%raw {|"Caml1999I017\x84\x95\xa6\xbe\0\0\0D\0\0\0\x10\0\0\x008\0\0\x004\xa0*MyExternal\xa0\xa0\xb0\x01\x03\xf1%hello@\xc0\xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfe@\xb0\xc0&_none_A@\0\xff\x04\x02A@@\x84\x95\xa6\xbe\0\0\0l\0\0\0\x0f\0\0\0:\0\0\0/\xa0\xa0*MyExternal\x900\xb3K@\b]?\xb6}\xec\xe1Q\xf5\x97\xb9\xe4\x06\xa0\xa0*Pervasives\x900\r\x01ZZ!6e\x9b\r\xe41\xbe\x7f\x15E\xbe\xa0\xa08CamlinternalFormatBasics\x900\x8b\x06\x9f\xca\x1eM\x93\x16\xb5\x88\xe5UO8\xbb$@\x84\x95\xa6\xbe\0\0\0\x01\0\0\0\0\0\0\0\0\0\0\0\0@%"|}]
);
let _ =
  BsBox.loadModule ~name:"MyExternal"
    ~cmi:([%raw
            {|"Caml1999I017\x84\x95\xa6\xbe\0\0\0f\0\0\0\x19\0\0\0V\0\0\0Q\xa0*MyExternal\xa0\xa0\xb0\x01\x03\xf3%hello@\xc0\xb0\xc1 \xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfc\xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfd@\x02\x05\xf5\xe1\0\0\xfe@\xb0\xc0&_none_A@\0\xff\x04\x02A@@\x84\x95\xa6\xbe\0\0\0\xf3\0\0\0(\0\0\0\x90\0\0\0w\xa0\xa0*MyExternal\x900\x02LzF\xe5\xf4\xb2\xdc|\xa1\xf5\xde3\xe4\xdf\"\xa0\xa0&String\x900e\x90\x7f\x1d\xde\xc3+\xe4\xc8\xa1\x90\x07\x91p\xe0\xf1\xa0\xa0*Pervasives\x900\r\x01ZZ!6e\x9b\r\xe41\xbe\x7f\x15E\xbe\xa0\xa0)Js_string\x900GV\xce|\x10H7Ib\x80\x9b\xb5F\".u\xa0\xa0%Js_re\x9006s\xb2X\x9a=\x93\xf6=\x05#\0\xa2\r\xd3f\xa0\xa0(Js_array\x900\x92\x1e\xbe\x88=\x94\xf1y@\x9d\x98\xefN\xd6\xdc\x0f\xa0\xa0\"Js\x900\xd3g\x87\x88u\xa2\xf2\xe6\x1b\xad\xa9\xc5\x81\x85lF\xa0\xa08CamlinternalFormatBasics\x900\x8b\x06\x9f\xca\x1eM\x93\x16\xb5\x88\xe5UO8\xbb$@\x84\x95\xa6\xbe\0\0\0\x01\0\0\0\0\0\0\0\0\0\0\0\0@%"|}])
    ~cmj:([%raw
            {|"Caml1999I017\x84\x95\xa6\xbe\0\0\0D\0\0\0\x10\0\0\x008\0\0\x004\xa0*MyExternal\xa0\xa0\xb0\x01\x03\xf1%hello@\xc0\xb0\xb3\x90\xb0C&string@@\x90@\x02\x05\xf5\xe1\0\0\xfe@\xb0\xc0&_none_A@\0\xff\x04\x02A@@\x84\x95\xa6\xbe\0\0\0l\0\0\0\x0f\0\0\0:\0\0\0/\xa0\xa0*MyExternal\x900\xb3K@\b]?\xb6}\xec\xe1Q\xf5\x97\xb9\xe4\x06\xa0\xa0*Pervasives\x900\r\x01ZZ!6e\x9b\r\xe41\xbe\x7f\x15E\xbe\xa0\xa08CamlinternalFormatBasics\x900\x8b\x06\x9f\xca\x1eM\x93\x16\xb5\x88\xe5UO8\xbb$@\x84\x95\xa6\xbe\0\0\0\x01\0\0\0\0\0\0\0\0\0\0\0\0@%"|}])

Runtime

The js artifact needs to be bundled in such a way that it can be accessed via require. This can either be accomplished using browserify, which requires the compiled modules to be in amdjs format, or you can provide your own require function like the external_module example does.

Licensing

The vendor directory contains files built from code in the BuckleScript repository. Refer to its Licensing section. Everything else is licensed under the MIT license.

Acknowledgement

Thanks to Hongbo Zhang for creating the BuckleScript compiler, and Alessandro Strada for figuring out and doing the necessary work to be able to include external modules.