@sig("a"/ H[(Eq, "a")] >> [("a", "b")] >> t(Maybe, "b"))
def lookup(key, assocs):
    """
    lookup :: Eq a => a -> [(a, b)] -> Maybe b

    lookup(key, assocs) looks up a key in an association list.
    """
    for k, value in assocs:
        if k == key:
            return Just(value)
    return Nothing


#=============================================================================#
## Searching with a predicate
dataset/ETHPy150Open billpmurphy/hask/hask/Data/List.py/lookup/swapped operands of `/`