map is:exact -package:text -package:charset -package:base-prelude -package:Cabal-syntax -package:blaze-html -package:imports -package:containers -package:case-insensitive -package:incipit-base -package:foldl -package:dlist -package:os-string package:basement
Map all element a from a block to a new block of b
Map all elements in a list