CatMaybes concatenates maybe values in a list into one list.
*Main> :t catMaybes catMaybes :: [Maybe a] -> [a] *Main> catMaybes [Just "a", Nothing, Nothing, Just "b"] ["a","b"]
CatMaybes concatenates maybe values in a list into one list.
*Main> :t catMaybes catMaybes :: [Maybe a] -> [a] *Main> catMaybes [Just "a", Nothing, Nothing, Just "b"] ["a","b"]