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| Date: | 2009-01-14 (08:54) |
| From: | Stéphane Glondu <steph@g...> |
| Subject: | Re: [Caml-list] why Hashtbl.t are not covarint? |
Radzevich Belevich a écrit :
> hashtbl.mli: type ('a,'b) t
> Why not "type ('a,+'b) t"?
For the same reason as 'a in 'a ref, i.e. mutable things cannot be
covariant.
Cheers,
--
Stéphane