A DSL for making music with CoffeeScript might look like this...

music.coffee

bpm 120

# BootsNCatsNBootsNCatsNBootsNCatsNBootsNCatsNBootsNCatsNBootsNCatsN
# http://i.imgur.com/sqmHC.jpg

drums = new DrumMachine()

n = (s) ->
    drums 'hihat', s
boots = (s) ->
    drums 'bassdrum', n s # the hihat is on every 1/2 beat
cats = (s) ->
    drums 'snare', n s # ditto
    
# 'xbeaty' means "for all beats z such that z % x == y"
on '2beat0', (s) ->
    boots s
on '2beat0.5', (s) ->
    n s
on '2beat1', (s) ->
    cats s
on '2beat1.5', (s) ->
    n s

# get some notes handy
fs5 = 739.989
a5 = 880.0
b5 = 987.767
cs6 = 1108.731
e6 = 1318.51
fs6 = 1479.978
gs6 = 1661.219

# for melodys, we have an array like [freq,dur,freq,dur,...]
melody = [     # "Kids" by MGMT
    # first 4 bars
    a5, 0.25
    b5, 0.25
    cs6, 0.25
    e6, 0.25
    fs6, 0.25
    gs6, 0.125
    fs6, 0.25
    e6, 0.25
    cs6, 1.125
    b5, 1
    # second 4 bars
    a5, 0.25
    b5, 0.25
    cs6, 0.25
    b5, 0.25
    a5, 0.25
    b5, 0.125
    a5, 0.25
    fs5, 0.25
    a5, 1
]

osc = Oscillator 'sine'

on '32beat0', (s) ->
    playMelody melody, osc, s

This is just an idea.