Node.js non-blocking Fibonacci written on CoffeeScript

fibonacci.coffee

###
Original project here: https://github.com/glenjamin/node-fib ,
this is CoffeeScript rewrite of the app. Nothing more, nothing less.
###

app = require("express").createServer()
port = "3000"

fibonacci = (n, callback) ->
    inner = (n1, n2, i) ->
        callback null, n2  if i > n
        func = (if i % 100 then inner else inner_tick)
        func n2, n1 + n2, i + 1

    inner_tick = (n1, n2, i) ->
        process.nextTick ->
            inner n1, n2, i

    if n is 1 or n is 2
        callback null, 1
    else
        inner 1, 1, 3

app.get "/:n", (req, res) ->
    fibonacci req.params.n, (err, number) ->
        res.send "#{number}"

app.listen port
console.log "server listens on localhost #{port}"