29 Jul
2011
29 Jul
'11
6:40 p.m.
http://www.cs.ox.ac.uk/jeremy.gibbons/publications/iterator.pdf
Interesting. However I don't understand why the instance in Section 5.5 is not already forbidden by the "purity law" traverse pure = pure and a "'no duplication' constraint" would be necessary. For example: traverse Id [1,2,3] = Id [1,1,2,2,3,3] /= Id [1,2,3] What am I missing? Can we derive Foldable laws from the Traversable laws? Sebastian