oo. I'd forgotten about fix. cycleM = fix . mplus gives a nice generic version that works on Lists & Sequences but falls afoul of the monomorphism restricti

oo. I'd forgotten about fix. cycleM = fix . mplus gives a nice generic version that works on Lists & Sequences but falls afoul of the monomorphism restriction, so it needs a type: cycleM :: (MonadPlus m) => m a -> m a cycleM = fix . mplus