Re: [Haskell] Empty instance declaration

ajb@spamcop.net wrote:

One thing that hasn't come up yet is that empty instance declarations are the only decent option (that I know of) that we have in the absence of real class aliases.

It does seem to me that compilers could reasonably distinguish between incomplete definition:

...

class (Monad m, Ord t) => ReVars m t where { } instance (Monad m, Ord t) => ReVars m t where { }

and intentionally incomplete definition: class (Monad m, Ord t) => ReVars m t instance (Monad m, Ord t) => ReVars m t Both syntaxes (with and without the 'where') are currently legal, but the latter is more obviously deliberate (at least to this human reader). Regards, Malcolm