Re: [Haskell-cafe] type class design

Hi, Uwe Schmidt wrote:

In the standard Haskell classes we can find both cases, even within a single class.

Eq with (==) as f and (/=) as g belongs to the 1. case

Note that the case of (==) and (/=) is slightly different, because not only can (/=) be defined in terms (==), but also the other way around. The default definitions of (==) and (/=) are mutually recursive, and trivially nonterminating. This leaves the choice to the instance writer to either implement (==) or (/=). Or, for performance reasons, both. Tillmann