• Simon Peyton Jones's avatar
    Fundeps work even for unary type classes · 801c2637
    Simon Peyton Jones authored
    The functional-dependency improvement functions,
       improveFromAnother
       improveFromInstEnv
    had a side-condition that said the type class has to have at
    least two arguments.  But not so, as Trac #12763 shows:
    
       class C a | -> a where ...
    
    is perfectly legal, albeit a bit of a corner case.
    801c2637
T5684.stderr 3.86 KB