Proposal for a more performant es5 target for es6 module transpilers

input.es6.js

import { readFile, readDir } from "fs";

export function mkdir() {
    // do stuff with readFile & readDir
}

export var count;

for(count = 0; count < 100;) {
    console.log(count++); // 0...99
}

for(count = 0; count < 100;) {
    console.log(++count); // 1...100
}

output.es5.js

System.register("shelly", [ "fs" ], function(bindings) {
    // import identifiers and non-function/non-class export identifiers gets hoisted
    var readFile, readDir, count;
    
    // Get live updates for the imported value
    bindings.import("readFile", function(newVal) { readFile = newVal });
    // note: need to do a pull for the initial value when this is called
    bindings.import("readDir", function(newVal) { readDir = newVal });
    
    // For functions and classes things just work...
    bindings.export("mkdir", function() { return mkdir });
    function mkdir() {}
    
    // initial export is immediately called to push out to any subscribers
    bindings.export("count", function() { return count });
    
    for(count = 0; count < 100;) {
        // push out the changes and return the second argument
        console.log(bindings.push("count", count++)); // 0...99
    }
    
    for(count = 0; count < 100;) {
        // by returning the second argument you get expected semantics
        console.log(bindings.push("count", ++count)); // 1...100
    }
});