An EXPERT PROGRAMMER explains OO

Because I know you were all having so much trouble with this difficult concept.

http://theunixgeek.blogspot.com/2007/11/understanding-object-oriented.html

>>34
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The 1, 2, 3, 4 are printed as a result of calling putStrLn on each element. The [(),(),(),()] is the resulting list from your mapM call.