implementation module IterableClass

import StdEnv

stepn :: Int !a -> a | step a
stepn 0 a = a
stepn n a = stepn (n-1) (step a)

rewindn :: Int !a -> a | rewind a
rewindn 0 a = a
rewindn n a = rewindn (n-1) (rewind a)

stepOrRewindn :: Int !a -> a | step, rewind a
stepOrRewindn 0 a = a
stepOrRewindn n a
| n < 0 = rewindn (0-n) a
| n > 0 = stepn n a