SuperCollider's SequenceableCollection blend, blendAt in CoffeeScript

sc-blend.coffee

# SuperCollider's SequenceableCollection blend, blendAt in CoffeeScript
# SEE ALSO:
# https://github.com/supercollider/supercollider/blob/master/SCClassLibrary/Common/Core/Object.sc
# http://danielnouri.org/docs/SuperColliderHelp/Collections/SequenceableCollection.html
# http://coleingraham.com/2012/12/31/notes-between-chromatic-just-intonation/
# http://mohayonao.github.com/subcollider.js/

class ArrayUtil
  # via https://github.com/supercollider/supercollider/blob/master/SCClassLibrary/Common/Core/Object.sc
  @blendAt: (array, index) ->
    return array[0] if index <= 0
    return array[array.length - 1] if index >= array.length - 1
    iMin = Math.ceil(index) - 1
    return MathUtil.blend(array[iMin], array[iMin + 1], Math.abs(index - iMin))

class MathUtil
  @scale: (value, lo, hi) ->
    (value * (hi - lo)) + lo
  @clamp: (v, min, max) ->
    Math.min(Math.max(v, min), max)
  # via https://github.com/supercollider/supercollider/blob/master/SCClassLibrary/Common/Core/Object.sc
  @blend: (a, b, blendFrac = 0.5) ->
    a + (blendFrac * (b - a))