map is:exact -package:text -package:dense-linear-algebra -package:base-prelude -package:case-insensitive -package:blaze-html -package:base -package:filepath -package:charset -package:insert-ordered-containers -package:dlist -package:Cabal-syntax -package:aeson package:basement
Map all element a from a block to a new block of b
Map all elements in a list