map -package:containers -package:ghc -package:basement -package:aeson -package:base-compat -package:incipit-base -package:dense-linear-algebra -package:monoidal-containers -package:charset -package:conduit -package:case-insensitive -package:filepath -package:dlist -package:pipes -package:regex-tdfa -package:hedgehog -package:base-compat-batteries -package:os-string -package:base-prelude -package:integration -package:base -package:text -package:vector -package:psqueues

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]

Combinator for the <map> element. Example:

map $ span $ toHtml "foo"

Result:

<map><span>foo</span></map>

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

O(n) map f xs is the ByteString obtained by applying f to each element of xs

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

Fold pairs into a map.

Apply a bijection over a list using map.

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

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.

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]

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.