Possible CS Generator Syntax

gistfile1.txt

koa = require 'koa'
app = koa()

generator firstn
  initialize: (limit) ->
    num = 0
    while num < limit
      yield num
      num += 1

generator repeat 
  initialize: (num) ->
    loop
      yield num

generator koa_res
  initialize: ->
    this.body = "Hello World!"

app.use koa_res

# use `new` keyword so that CS can check
# to make sure people are using generators correctly
# (you have to initialize them first)
x = new (firstn 1000)

# these functions are all part of the ES6 spec
x.next()
x.send(5)
x.throw()
x.close()
x.iterate()

# ----------------
// Proposed compilation

var koa, app, firstn, repeat, koa_res, x;

koa = require("koa");
app = koa();

firstn = function*(limit) {
  var num;
  num = 0;
  while(num < limit) {
    yield num;
    num += 1;
  }
};

repeat = function*(num) {
  while(true) {
    yield num;
  }
};

koa_res = function*() {
  this.body = "Hello World!";
};

app.use(koa_res);

x = firstn(1000);

x.next();
x.send(5);
x.throw();
x.close();
x.iterate();

-------
PROS: 
  + consistent with CS class layout
  + allows CS to check for proper generator usage (initialization, etc.)
  + more beginner friendly (you can't make a generator unless you really know what you're doing)
  + allows CS to hide generator internals
  + similar to JS by defining generator in function signature
  + way easier for parser to figure out return values (possibly extend Class in lexer).
  + you can have empty generators if you really want them (analogous to `fn = ->` for a regular function, which compiles to `var fn; fn = function() {};` )

CONS:
  + more verbose than auto-detection
  + generator isn't currently reserved (the structure prevents confusion, though).