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