map -package:text -package:containers -package:bytestring -package:vector -package:rio

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, ...]

this means that map id == id

Examples

>>> map (+1) [1, 2, 3]
[2,3,4]

>>> map id [1, 2, 3]
[1,2,3]

>>> map (\n -> 3 * n + 1) [1, 2, 3]
[4,7,10]

Map a function over a NonEmpty stream.

Map a function over all values in the 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"]

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

Apply a transformation to all values in a stream. Subject to fusion

Apply a transformation to all values in a stream. Subject to fusion Since 0.3.0

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]

Generates a map using a Range to determine the length. This may fail to generate anything if the keys produced by the generator do not account for a large enough number of unique items to satify the required map size.

Apply a function to each element of a Stream, lazily

Combinator for the <map> element. Example:

map $ span $ toHtml "foo"

Result:

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

Apply a function to all values flowing downstream

map id = cat

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

map f xs is the DList obtained by applying f to each element of xs. <math>(length (toList xs)). map obeys the law:

toList (map f xs) = map f (toList xs)

map f xs is the DNonEmpty obtained by applying f to each element of xs. <math>(length (toNonEmpty xs)). map obeys the law:

toNonEmpty (map f xs) = map f (toNonEmpty xs)

Fold pairs into a map.

Maps a pure function over an InputStream. map f s passes all output from s through the function f. Satisfies the following laws:

Streams.map (g . f) === Streams.map f >=> Streams.map g
Streams.map id === Streams.makeInputStream . Streams.read

Standard map on the elements of a stream.

>>> S.stdoutLn $ S.map reverse $ each (words "alpha beta")
ahpla
ateb

Decode a Map from a toMap expression or generally a Prelude.Map.Type.

>>> input (Dhall.map strictText bool) "toMap { a = True, b = False }"
fromList [("a",True),("b",False)]

>>> input (Dhall.map strictText bool) "[ { mapKey = \"foo\", mapValue = True } ]"
fromList [("foo",True)]

If there are duplicate mapKeys, later mapValues take precedence:

>>> let expr = "[ { mapKey = 1, mapValue = True }, { mapKey = 1, mapValue = False } ]"

>>> input (Dhall.map natural bool) expr
fromList [(1,False)]