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

[Stefan Holdermans]

Mike,

> For those of us who aren't type theorists: What's a "negative  
> datatype"?

A type that has a recursive call in negative position. Negative  
positions are the argument positions in function types. (But if a  
function type appears in a negative position, then its own argument  
position is denoted positive and its result position negative.)

Cheers,

   Stefan