Re: [Haskell-cafe] Church Encoding Function

On 3/10/07, Robert Dockins wrote:

I'm pretty sure you can define a catamorphism for any regular algebraic data type. I'm not 100% sure what the story is for non-regular (AKA nested) datatypes.

They do exist: Initial Algebra Semantics is Enough! Patricia Johann and Neil Ghani. http://crab.rutgers.edu/~pjohann/tlca07.pdf code: http://www.cs.nott.ac.uk/~nxg/Tlca07.hs Jim