> Sound.SC3.UGen.Help.viewSC3Help "LastValue"
> Sound.SC3.UGen.DB.ugenSummary "LastValue"

> import Sound.SC3

> let x = mouseX KR 100 400 Linear 0.1
> in audition (out 0 (sinOsc AR (lastValue x 40) 0 * 0.1))

Difference between currrent and the last changed
> let {x = mouseX KR 0.1 4 Linear 0.1
>     ;f = abs (lastValue x 0.5 - x) * 400 + 200}
> in audition (out 0 (sinOsc AR f 0 * 0.2))