> import Sound.DF

> map (\i -> lin_exp i 1 2 1 3) [1, 1.1 .. 2]

> do { s <- lf_saw 0.25 0.0
>    ; o <- sin_osc (lin_exp (s + 1.0) 0.0 2.0 220.0 440.0) 0.0
>    ; audition [] (out1 (o * 0.1)) }