map is:exact -package:text -package:base-compat-batteries -package:dense-linear-algebra -package:base-prelude -package:case-insensitive -package:containers -package:filepath -package:charset -package:imports -package:Cabal-syntax -package:invertible -package:monoidal-containers package:basement
Map all element a from a block to a new block of b
Map all elements in a list