However, I have this feeling that
bar :: forall a . Id a -> String
with a type family Id *is* parametric in the sense that no matter what a
is, the result always has to be the same. Intuitively, that's because we may
not "pattern match on the branch" of a definition like
type instance Id String = ..
type instance Id Int = ..
..
But in a degenerate case there could be just this one instance:
type instance Id x = GADT x
which then reduces this example to the GADT case of which you said that is
was "clearly parametric".
Tom
--
Tom Schrijvers
Department of Computer Science
K.U. Leuven
Celestijnenlaan 200A
B-3001 Heverlee
Belgium
tel: +32 16 327544
e-mail: [EMAIL PROTECTED]
url: http://www.cs.kuleuven.be/~toms/
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