Re: [ghc-devs]: Explicit inequality evidence

2016-12-21 Thread Anthony Clayden
> On Dec 13, 2016, at 1:02 AM, David Feuer wrote: > >> On Tue, Dec 13, 2016 at 12:49 AM, Oleg Grenrus wrote: >> >> I assume that in your rules, variables are not type families, otherwise >> >> x /~ y => f x /~ f y doesn't hold if `f` isn't injective. (e.g. type family F x where F x = ()) >> o

[ghc-devs]: Explicit inequality evidence

2016-12-17 Thread Anthony Clayden
[transferring to -users, because there's a much wider discussion] > > On Dec 13, 2016, at 15:04, Richard Eisenberg wrote: > > I've thought about inequality on and off for years now, The subject has appeared (in various guises) on Haskell forums since well before 2002 [1] -- which went into the 'O