24 Aug
2012
24 Aug
'12
3:44 a.m.
More specifically (assuming I understood the statement correctly): Suppose I have two base functors F1 and F2 and folds for each: fold1 :: (F1 a -> a) -> (μF1 -> a) and fold2 :: (F2 a -> a) -> (μF2 -> a). Now suppose I have two algebras f :: F1 μF2 -> μF2 and g :: F2 A -> A. When is the composition (fold2 g) . (fold1 f) :: μF1 -> A a catamorphism? On Thu, Aug 23, 2012 at 10:11 PM, Sebastien Zany < sebastien@chaoticresearch.com> wrote:
From page 3 of http://research.microsoft.com/en-us/um/people/emeijer/Papers/meijer94more.pd... :
it is not true in general that catamorphisms are closed under composition
When is this true?