14 Oct
2008
14 Oct
'08
11:51 p.m.
George Pollard wrote:
I'm a little confused. Why is this allowed:
instance Eq Blah where x == y = True
But not this:
Illegal instance declaration for `Stringable [Char]' (All instance types must be of the form (T a1 ... an) where a1 ... an are distinct type *variables* Use -XFlexibleInstances if you want to disable this.) In the instance declaration for `Stringable [Char]'
'Blah' isn't a type variable, is it? Is my brain just not working right today?
Just in case: n=0 for "instance Eq Blah", i.e., "T a1 ... an" becomes "T".