map is:exact -package:text -package:charset -package:bytestring -package:case-insensitive -package:conduit -package:insert-ordered-containers -package:base-compat-batteries -package:dlist -package:monoidal-containers -package:incipit-base -package:aeson -package:os-string package:basement
Map all element a from a block to a new block of b
Map all elements in a list