[Haskell-cafe] Hood on Hackage is an interesting way to see intermediate data structures.

[caseyh at istar.ca]

Hood on Hackage is an interesting way to see intermediate data structures.

{-# LANGUAGE NoMonomorphismRestriction #-}

-- Fold Behaviour Observed

module Folding where

     -- See Hood on Hackage
     import Observe
     import Data.List

     n = 10::Int
     fr = foldr (observe "Add" (+)) 0 [1..n]
     fl = foldl (observe "Add" (+)) 0 [1..n]
     frr = foldr (observe "Add" (+)) 0 (reverse [1..n])
     flr = foldl (observe "Add" (+)) 0 (reverse [1..n])

     fro = printO fr
     flo = printO fl
     frro = printO frr
     flro = printO flr

     fl' = foldl' (observe "Add" (+)) 0 [1..n]
     flr' = foldl' (observe "Add" (+)) 0 (reverse [1..n])

     flo' = printO fl'
     flro' = printO flr'