composed_await_demo.coffee

# mock-up async for test in browser
readfile=(file, cb)->
  setTimeout (->
    console.log("readfile(#{file}) callback")
    cb(null, file+'data')
  ), 500

parse=(data, cb)->
  setTimeout (->
    console.log("parse(#{data}) callback")
    cb(data, data.charCodeAt(0))
  ), 100

# actual code
fileArray=['a', 'b', 'c']
dict={}

await
  for file in fileArray
    ((file, autocb)->
      # autocb keyword: "return means callback"
      await readfile file, defer(err, data)
      await parse data, defer(k, v)
      dict[k]=v
    )(file, defer())

console.log JSON.stringify dict