| since this claims that it will take a Bool and produce a value of type
b
| for all types b. However, would it be all right to say (in
| pseudo-Haskell):
|
| f :: exists b . Bool - b
| f x = x
But this is a singularly useless function, because it produces a result
of utterly unknown type, so
Hi Simon, all,
Here's a less complicated variant of the same problem:
class C a b | a - b where {}
instance C Int Int where {}
f :: (C Int b) = Int - b
f x = x
This is interesting, but I'm not entirely sure what the problem is (from a
theoretical, not
Suppose we are in case 1. Then the programmer has written a too-general
type signature on f. The programmer *must* know that b=Int in this case
otherwise his function definition makes no sense. However, I don't really
see a reason why this should be an error rather than just a warning. If
