map is:exact -package:text -package:containers -package:blaze-html -package:case-insensitive -package:base -package:base-compat-batteries -package:ghc -package:foldl -package:imports -package:invertible -package:monoidal-containers -package:base-compat package:basement
Map all element a from a block to a new block of b
Map all elements in a list