Fix #2201: Less aggressive type application reduction for better inference #2204
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Previously we believed that reducing type applications did not affect
type inference as long as the reduced type constructor had the same
arity as the unreduced one, for example reducing
Foo[X, Y]
is finewhen
Foo
is defined as:but not when it's defined as:
But this is not a sufficient condition: the bounds of the type
constructor arguments also matter for type inference, so we need to be
more strict and disallow reductions in cases like:
and: