David Hopwood wrote:
> Joe Marshall wrote:
>
>>(defun blackhole (argument)
>> (declare (ignore argument))
>> #'blackhole)
>
> This is typeable in any system with universally quantified types (including
> most practical systems with parametric polymorphism); it has type
> "forall a . a -> #'blackhole".
Ignore this answer; I misinterpreted the code.
I believe this example requires recursive types. It can also be expressed
in a gradual typing system, but possibly only using an unknown ('?') type.
ISTR that O'Caml at one point (before version 1.06) supported general
recursive types, although I don't know whether it would have supported
this particular example.
--
David Hopwood <[EMAIL PROTECTED]>
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