map -package:containers -package:ghc -package:insert-ordered-containers -package:charset -package:aeson -package:blaze-html -package:bytestring -package:base-compat-batteries -package:filepath -package:os-string -package:amazonka-core -package:incipit-base -package:imports -package:hedgehog -package:dense-linear-algebra -package:basement -package:regex-tdfa -package:conduit -package:vector -package:cql -package:Cabal-syntax -package:base-prelude -package:foldl -package:dlist

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]
[2,3,4]

Map a function over a NonEmpty stream.

Transform the original string-like value but keep it case insensitive.

Apply a bijection over a list using map.

Apply a function to all values flowing downstream

map id = cat

map (g . f) = map f >-> map g

O(n) Modify every value in the queue.

O(n) Modify every value in the queue.

O(n) Modify every value in the queue.

O(n) map f t is the Text obtained by applying f to each element of t. Example:

>>> let message = pack "I am not angry. Not at all."

>>> T.map (\c -> if c == '.' then '!' else c) message
"I am not angry! Not at all!"

Performs replacement on invalid scalar values.

O(n) map f xs is the Stream Char obtained by applying f to each element of xs. Properties

unstream . map f . stream = map f

O(n) map f t is the Text obtained by applying f to each element of t. Performs replacement on invalid scalar values.

Transform this map by applying a function to every value.

Transform this set by applying a function to every value. The resulting set may be smaller than the source.

>>> HashSet.map show (HashSet.fromList [1,2,3])
HashSet.fromList ["1","2","3"]

Map a function over a Stream

Type-level fmap for type-level functors. Note: this name clashes with Map from containers. FMap is provided as a synonym to avoid this.

Example

>>> data Example where Ex :: a -> Example  -- Hide the type of examples to avoid brittleness in different GHC versions

>>> data AddMul :: Nat -> Nat -> Exp Nat

>>> type instance Eval (AddMul x y) = (x TL.+ y) TL.* (x TL.+ y)

>>> :kind! Ex (Eval (Map (AddMul 2) '[0, 1, 2, 3, 4]) :: [Nat])
Ex (Eval (Map (AddMul 2) '[0, 1, 2, 3, 4]) :: [Nat]) :: Example
= Ex [4, 9, 16, 25, 36]

A Map from keys k to values a. The Semigroup operation for Map is union, which prefers values from the left operand. If m1 maps a key k to a value a1, and m2 maps the same key to a different value a2, then their union m1 <> m2 maps k to a1.

Hash-table, based on STM-specialized Hash Array Mapped Trie.

Invariant preserving version of Map from the containers packages, suitable for use with Uniplate. Use toMap to construct values, and fromMap to deconstruct values.

Monadic variant of mapAccumL.

Map both the return value and final generator of a computation using the given function.

• runRand (mapRand f m) = f . runRand
  m