Data.Map

Note: You should use Data.Map.Strict instead of this module if:

• You will eventually need all the values stored.
• The stored values don't represent large virtual data structures to be lazily computed.

An efficient implementation of ordered maps from keys to values (dictionaries).

These modules are intended to be imported qualified, to avoid name clashes with Prelude functions, e.g.

  import qualified Data.Map as Map

The implementation of Map is based on size balanced binary trees (or trees of bounded balance) as described by:

• Stephen Adams, "Efficient sets: a balancing act", Journal of Functional Programming 3(4):553-562, October 1993, http://www.swiss.ai.mit.edu/~adams/BB/.
• J. Nievergelt and E.M. Reingold, "Binary search trees of bounded balance", SIAM journal of computing 2(1), March 1973.

Note that the implementation is left-biased -- the elements of a first argument are always preferred to the second, for example in union or insert.

Operation comments contain the operation time complexity in the Big-O notation (http://en.wikipedia.org/wiki/Big_O_notation).

Documentation

module Data.Map.Lazy

insertWith' :: Ord k => (a -> a -> a) -> k -> a -> Map k a -> Map k a

Deprecated. As of version 0.5, replaced by insertWith.

O(log n). Same as insertWith, but the value being inserted to the map is evaluated to WHNF beforehand.

For example, to update a counter:

 insertWith' (+) k 1 m

insertWithKey' :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k a -> Map k a

Deprecated. As of version 0.5, replaced by insertWithKey.

O(log n). Same as insertWithKey, but the value being inserted to the map is evaluated to WHNF beforehand.

insertLookupWithKey' :: Ord k => (k -> a -> a -> a) -> k -> a -> Map k a -> (Maybe a, Map k a)

Deprecated. As of version 0.5, replaced by insertLookupWithKey.

O(log n). Same as insertLookupWithKey, but the value being inserted to the map is evaluated to WHNF beforehand.

fold :: (a -> b -> b) -> b -> Map k a -> b

Deprecated. As of version 0.5, replaced by foldr.

O(n). Fold the values in the map using the given right-associative binary operator. This function is an equivalent of foldr and is present for compatibility only.

foldWithKey :: (k -> a -> b -> b) -> b -> Map k a -> b

Deprecated. As of version 0.4, replaced by foldrWithKey.

O(n). Fold the keys and values in the map using the given right-associative binary operator. This function is an equivalent of foldrWithKey and is present for compatibility only.