steshaw

1. http://pragprog.com/magazines/2012-08/thinking-functionally-with-haskell
2. http://pragprog.com/magazines/2012-09/thinking-functionally-with-haskell
3. http://pragprog.com/magazines/2012-10/thinking-functionally-with-haskell
4. http://pragprog.com/magazines/2012-11/thinking-functionally-with-haskell
5. http://pragprog.com/magazines/2012-12/web-programming-in-haskell
6. http://pragprog.com/magazines/2013-01/web-programming-in-haskell-part-ii
7. http://pragprog.com/magazines/2013-03/uncle-bob-and-functional-programming
8. http://pragprog.com/magazines/2013-04/dependent-types
9. http://pragprog.com/magazines/2013-05/dependent-types-part-ii
10. http://pragprog.com/magazines/2013-06/unification

paulcc

-- compiles with ghc(i) 7.4.1
import Data.Map (Map, empty, insertWith, toList)
import Data.List(groupBy, group, sortBy, sort)

{- To recap from the main article, we want to define "group_on" via "groupBy", so that its 
   type is something like (b -> b -> Bool) -> (a -> b) -> [a] -> [(b, [a])]

   The method here is to work with a concrete example and gradually massage it 
   into the form we want - using the REPL