::class[Sequence]
::value[!, getList]
-::value[elem]
+::value[elem, elemIndex]
::value[filter, concatMap]
::value[foldl, foldl1, foldr]
::value[unfoldl, unfoldr]
## Monads
::class[Monad]
-::value[>>]
+::value[>>, >=>]
::class[FunctorM]
::value[repeatForever]
::class[MonadZero]
::value[guard]
::class[MonadPlus, MonadOr]
::value[ignoreM]
+::class[MonadE]
+::value[compE]
+::class[MonadZeroE]
# Side-effects