Rescript-compiler: ES6 modules

[bobzhang]

After playing around with rollup, I think to get the dead code elimination from rollup is quite easy (need check with webpack too)

.hi.js

function test$1 (n){
    return n + 1
}

function test$2(n){
    return n + 3    
}

export { test$1 as test, test$2 as test2}

.fib.js

import * as hi from './hi'
function test$1(n){    
    return hi.test(n) + 1;
}

function fib2 (n) {
    return hi.test2(n) * 2 ;
}

var b = 2;

var c = 3;

var d = c + 2 ;

console.log(b);

export { test$1 as fib, fib2, d}

.app.js

import * as fib from './fib'

 var x = fib.fib (fib.d)

 console.log(x)

so I run the command rollup -f iife app.js

(function () {
'use strict';

function test$1$1 (n){
    return n + 1
}

function test$1(n){
    return test$1$1(n) + 1;
}

var b = 2;

var c = 3;

var d = c + 2;

console.log(b);

var x = test$1 (d);

 console.log(x);

}());

the output looks good, rollup is smarter than I thought, it can handle * based import

[bobzhang]

webpack seems to do a horrible job..

[OvermindDL1]

webpack seems to do a horrible job..

Heh, yes it does, I have had, to be quite frank, horrible experiences with webpack, hence why I use brunch as my 'javascript build engine', but even that has been removed in my recent projects in exchange for just raw npm scripts usage (why need a build system when npm already 'is' one), so I've just been calling browserify (and recently rollup.js, it does the same as browserify, but better and faster, as you see). :-)

[bobzhang]

fixed in master

[jordwest]

Just a note for anyone else who comes across this - to compile with ES6 modules you'll need to add the following key to bsconfig.json:

"package-specs": ["es6"],

After compiling, find the ES6 modules in lib/es6.

[aaronshaf]

Even after doing this, a small app that builds a list, maps it, and outputs it is 25k.

[abdullahibnnadjo]

@aaronshaf OCaml Lists need a lot of code from the standard library. If it's relevant, you can use arrays (with Js.Array.* functions) which don't require any overhead?

Also, using webpack with module concatenation and uglifyjs plugins with es6 modules does a very good job for dead code elimination (and even better with the define plugin for conditional compilation), I have basically 0 unused code with this.