ln-stream

for each line processor

attach proc for a line and defer the post-processor

lnstream = require('ln-stream')
lnstream(filename, proc, defer)

wc-like program

lnstream = require 'ln-stream'
 
lines = 0
words = 0
chars = 0
 
# processer for each line 
proc = (line) ->
  lines += 1
  words += line.split ' '
               .length
  chars += line.length
 
# after the all lines 
defer = () ->
  console.log "%d %d %d", lines, words, chars
 
lnstream './README.md', proc, defer
 
# => 36 120 504 

simple multi-process (pseudo)

To realize true multi-process, you can use the functions in child_process.

seq 1000 1003 > list

proc = (id) ->
  setTimeout (-> console.log id), id
lnstream './list', proc, (-> 0)

[bash] $ time coffee test.coffee
1000
1001
1002
1003

real    0m1.197s
user    0m0.113s
sys     0m0.036s