map is:exact -package:text -package:base -package:containers -package:Cabal-syntax -package:aeson -package:base-compat -package:imports -package:base-compat-batteries -package:dlist -package:base-prelude -package:case-insensitive -package:foldl package:basement
Map all element a from a block to a new block of b
Map all elements in a list