Notation question

[David Scarlett]

----- Original Message -----
From: "Juan Carlos Arevalo Baeza" <jcab@roningames.com>
To: <haskell@haskell.org>
Sent: Tuesday, May 29, 2001 11:02 AM
Subject: Notation question


>
>     Just a very naive question, because I'm really curious. I've seen in
> previous messages here discussions about type systems using this kind of
> notation:
>
> >  G |- f :: all x::S . T   G |- s :: S
> >--------------------------------------
> >          G |- f s :: [s/x]T
>
>     I'd never seen it before, and a few searches I've launched over the
net
> have turned up just a couple more examples of this notation, but without a
> single reference to how it works or what it means, or even what it's
> called, for that matter.
>

I think I've seen it (or something similar) in an imperative language called
"Imp".