map is:exact -package:text -package:dense-linear-algebra -package:amazonka-core -package:aeson -package:Cabal-syntax -package:containers -package:ghc -package:base-compat -package:insert-ordered-containers -package:dlist -package:invertible -package:base-compat-batteries package:basement
Map all element a from a block to a new block of b
Map all elements in a list