map is:exact -package:text -package:ghc -package:conduit -package:containers -package:charset -package:base-compat-batteries -package:Cabal-syntax -package:incipit-base -package:base-compat -package:base-prelude -package:foldl -package:dlist package:basement
Map all element a from a block to a new block of b
Map all elements in a list