[Haskell-cafe] Re: [Haskell] Fixpoint combinator without recursion

Edsko, (Moved to Haskell Cafe.)

It is well-known that negative datatypes can be used to encode recursion, without actually explicitly using recursion. As a little exercise, I set out to define the fixpoint combinator using negative datatypes. I think the result is kinda cool :) Comments are welcome :)

Yeah, it's rather cool. IIRC, this style of encoding of recursion operators is attributed to Morris. Before the advent of equality coercions, GHC typically had problems generating code for these kinds of definitions. Did you test this with a release version? If so, how did you get around the code- generation problem? Is it the NOINLINE pragma that does the trick? Cheers, Stefan