First effort at rand()

[yaxu]

Seems to work, but

"c4*16".velocity(rand)

only gives one random value per cycle. This works as expected:

"c4*16".velocity(rand.struct("t*16"))

This is probably an issue with applicative (or maybe monad) or the way that velocity is combined with value.

Contributes to #46 and #31

[yaxu]

Applicative looks fine:

console.log("3 4 2".fmap(a => b => a + b).appLeft(rand).firstCycle())
0: Object { whole: {…}, value: 2.168623458594084, stateful: false, … }
​1: Object { whole: {…}, value: 4.2604806162416935, stateful: false, … }
​2: Object { whole: {…}, value: 1.9786392766982317, stateful: false, … }

So I think this will be solved with #60