@mrmurphy/let-anything v0.1.2

hello-ppx-esy

A project that includes the minimum configuration for a ppx project using Reason and Esy.

It implements a very basic ppx that transforms the [%test] extension into the number literal 42.

So, the code:

let fourtyTwo = string_of_int([%test]);

Is transformed into:

let fourtyTwo = string_of_int(42);

Usage

You need Esy, you can install the beta using npm:

% npm install -g esy@latest

Then you can install the project dependencies using:

% esy install

Then build the project dependencies along with the project itself:

% esy build

After building, you should see an executable in _esy/default/build/default/.ppx/test_ppx/ppx.exe. This will be the binary used by BuckleScript in the example below.

Example

You can see an example of usage in a BuckleScript project in the /example folder. The most relevant point is the ppx-flags in example/bsconfig.json, that is pointing to the ppx executable:

  "ppx-flags": [
    "../_esy/default/build/default/.ppx/test_ppx/ppx.exe --as-ppx"
  ],

To compile the example:

% esy install

Then you can run

% yarn build

or

% npm run build

At that point, you should see the file src/Index.bs.js with the following output:

// Generated by BUCKLESCRIPT VERSION 4.0.7, PLEASE EDIT WITH CARE
'use strict';


var fourtyTwo = String(42);

console.log(fourtyTwo);

exports.fourtyTwo = fourtyTwo;
/* fourtyTwo Not a pure module */