Re: Local definitions in the class instances

On 27 January 2011 17:11, Iavor Diatchki wrote:

instance Num Wrapped where    local      lift2 f (Wrapped a) (Wrapped b) = Wrapped (f a b)      lift f (Wrapped a) = Wrapped (f a)    in     (+) = lift2 (+)     (-) = lift2 (-)     (*) = lift2 (*)     abs = lift abs     signum = lift signum

Local declarations at module scope can be emulated using pattern bindings: """ (foo, bar) = (foo, bar) where foo = .. bar = .. private = ... """ If instance declarations supported pattern bindings you could get the same effect for your instances too. This would be a minimal change that avoided introducing any extra syntax. Cheers, Max