map -package:Cabal -package:base -package:text -package:pipes -package:unordered-containers package:dlist -is:exact

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)