Wildcard type annotations

Einar Karttunen ekarttun at cs.helsinki.fi
Mon Jan 23 15:14:20 EST 2006

On 23.01 18:41, Andres Loeh wrote:
>   * if you have multiple underscores, they're all different, I guess;
>     but wouldn't you want also to be able to say that a type is
>     "_a -> _a" for some "_a"?

I think this can be done:

type IdApp a = a -> a

foo :: IdApp _
foo = ...

would then be translated as

foo :: exists a. IdApp a
that is
foo :: exists a. a -> a

- Einar Karttunen

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