map -package:Cabal -package:base -package:text -package:pipes -package:containers -package:regex-tdfa -package:bytestring -package:vector -package:unordered-containers -package:case-insensitive -package:filepath -package:rio package:numeric-prelude

map f xs is the list obtained by applying f to each element of xs, i.e.,

map f [x1, x2, ..., xn] == [f x1, f x2, ..., f xn]
map f [x1, x2, ...] == [f x1, f x2, ...]

>>> map (+1) [1, 2, 3]

Apply a function on a specific element if it exists, and another function to the rest of the map.

Map each element of a structure to a monadic action, evaluate these actions from left to right, and collect the results. For a version that ignores the results see mapM_.

Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results. For a version that doesn't ignore the results see mapM. As of base 4.8.0.0, mapM_ is just traverse_, specialized to Monad.

DiscreteMap was originally intended as a type class that unifies Map and Array. One should be able to simply choose between - Map for sparse arrays - Array for full arrays. However, the Edison package provides the class AssocX which already exists for that purpose. Currently I use this module for some numeric instances of Data.Map.

Map a function over all the elements of a container and concatenate the resulting lists.

Using ApplicativeDo: 'fmap f as' can be understood as the do expression

do a <- as
pure (f a)

with an inferred Functor constraint.