[Haskell-cafe] Comtrol.Monad.when

Any reason why "Control.Monad.when :: Monad m => Bool -> m () -> m ()" doesn't have type "Monad m => Bool -> m a -> m ()" instead? Just seems a bit of a waste to have the restriction without need. I find myself needing to add the extra spurious "return ()" at the end more often than not. I made an alternate "when_" for my own use, but... JCAB