map -package:containers -package:charset -package:invertible -is:exact -package:conduit -package:monoidal-containers -package:blaze-html 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)