map -package:containers -package:Cabal-syntax -package:insert-ordered-containers -package:foldl -package:case-insensitive -package:base-compat -package:base-compat-batteries -is:exact is:exact -package:blaze-html -package:dlist -package:hedgehog package:basement
Map all element a from a block to a new block of b
Map all elements in a list