It's hard to improve on a 20 line Awk program for generating text but I thought it would be fun to investigate a Haskell solution.
Why can't I cons an element onto an existing list?
Michael
Prelude Data.List Data.Map> insertWith (:) ("Moby", "Dick") "will" (fromList [(("Joe", "Blow"),["is"]), (("Moby", "Dick"),["may"])])
<interactive>:1:11:
Occurs check: cannot construct the infinite type: a = [a]
Expected type: a
Inferred type: [a]
In the first argument of `insertWith', namely `(:)'
In the expression:
insertWith
(:)
("Moby", "Dick")
"will"
(fromList [(("Joe", "Blow"), ["is"]), (("Moby", "Dick"), ["may"])])
Prelude Data.List Data.Map>