# Map

An efficient implementation of ordered maps from keys to values (dictionaries). This module re-exports the value lazy Data.Map.Lazy API, plus several deprecated value strict functions. Please note that these functions have different strictness properties than those in Data.Map.Strict: they only evaluate the values inserted into the map. For example, the default value to insertWith' is only evaluated if it's used, i.e. because there's no value for the key already or because the higher-order argument that combines the old and new value uses it. 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).
A Map from keys k to values a.
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, ...]
O(n) map f xs is the ByteString obtained by applying f to each element of xs
O(n) map f t is the Text obtained by applying f to each element of t. Subject to fusion. Performs replacement on invalid scalar values.
O(n*min(n,W)). map f s is the set obtained by applying f to each element of s. It's worth noting that the size of the result may be smaller if, for some (x,y), x /= y && f x == f y
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. This function is subject to array fusion.
O(n). Map a function over all values in the map. > map (++ "x") (fromList [(5,"a"), (3,"b")]) == fromList [(3, "bx"), (5, "ax")]
O(n). Map a function over all values in the map. > map (++ "x") (fromList [(5,"a"), (3,"b")]) == fromList [(3, "bx"), (5, "ax")]
O(n*log n). map f s is the set obtained by applying f to each element of s. It's worth noting that the size of the result may be smaller if, for some (x,y), x /= y && f x == f y
mapM f is equivalent to sequence . map f.
mapM_ f is equivalent to sequence_ . map f.
The mapAccumL function behaves like a combination of map and foldl; it applies a function to each element of a list, passing an accumulating parameter from left to right, and returning a final value of this accumulator together with the new list.
The mapAccumL function behaves like a combination of fmap and foldl; it applies a function to each element of a structure, passing an accumulating parameter from left to right, and returning a final value of this accumulator together with the new structure.
The mapAccumR function behaves like a combination of map and foldr; it applies a function to each element of a list, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new list.
The mapAccumR function behaves like a combination of fmap and foldr; it applies a function to each element of a structure, passing an accumulating parameter from right to left, and returning a final value of this accumulator together with the new structure.
The mapAndUnzipM function maps its first argument over a list, returning the result as a pair of lists. This function is mainly used with complicated data structures or a state-transforming monad.
This function maps one exception into another as proposed in the paper "A semantics for imprecise exceptions".
This function maps one exception into another as proposed in the paper "A semantics for imprecise exceptions".
Map each element of a structure to a monadic action, evaluate these actions from left to right, and ignore the results.
The mapMaybe function is a version of map which can throw out elements. In particular, the functional argument returns something of type Maybe b. If this is Nothing, no element is added on to the result list. If it just Just b, then b is included in the result list.
O(n). The function mapAccum threads an accumulating argument through the map in ascending order of keys. > let f a b = (a ++ b, b ++ "X") > mapAccum f "Everything: " (fromList [(5,"a"), (3,"b")]) == ("Everything: ba", fromList [(3, "bX"), (5, "aX")])
O(n). The function mapAccum threads an accumulating argument through the map in ascending order of keys. > let f a b = (a ++ b, b ++ "X") > mapAccum f "Everything: " (fromList [(5,"a"), (3,"b")]) == ("Everything: ba", fromList [(3, "bX"), (5, "aX")])
O(n) Like a combination of map and foldl'. Applies a function to each element of a Text, passing an accumulating parameter from left to right, and returns a final Text. Performs replacement on invalid scalar values.
The mapAccumL function behaves like a combination of map and foldl; it applies a function to each element of a ByteString, passing an accumulating parameter from left to right, and returning a final value of this accumulator together with the new ByteString.