[Haskell-cafe] Re: instance Eq (a -> b)

Thomas Davie wrote:

Certainly bottom is a value, and it's a value in *all* Haskell types.

This is a matter of interpretation. If you consider bottom to be a value, then all the laws fail. For instance, (==) is supposed to be reflexive, but "undefined == undefined" is not True for almost any type. For this reason I recommend "fast and loose reasoning": http://www.cs.nott.ac.uk/~nad/publications/danielsson-et-al-popl2006.html -- Ashley Yakeley