Still some question: Ok a is not a type but Integer is a type . But a can be instantiated to integer. This comes pretty close to call a therefore a type variable, Isn't it?
And otherwise why writing forall a etc. Regards Scott ----- Original Message ----- From: "Scott J." <[EMAIL PROTECTED]> To: "Jon Cast" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Monday, August 19, 2002 4:09 AM Subject: Re: Question aboutthe use of an inner forall > Still some question: Ok a is a type and Integer is a type . But a can be > instantiated to integer. This comes pretty close to call a therefore a type > variable. > > Regards > > Scott > > ----- Original Message ----- > From: "Jon Cast" <[EMAIL PROTECTED]> > To: "Scott J." <[EMAIL PROTECTED]> > Cc: "Ashley Yakeley" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > Sent: Monday, August 19, 2002 3:48 AM > Subject: Re: Question aboutthe use of an inner forall > > > > "Scott J." <[EMAIL PROTECTED]> wrote: > > > A question: s is not a type variable as a isn't it? I mean a can be > > > of type Integer while s cannot. > > > > Guessing at your question: > > > > a has no type (and neither does s); it /is/ a type. In Haskell, types > > have kinds. And, both a and s have kind *. > > > > Now then, the user can instantiate a to Integer, yes. And the user > > cannot instantiate s to anything---that's what the `forall' is for. > > runST will (theoretically) instantiate s to something. That could be > > Integer if the language implementors felt like it. The user of runST > > certainly has to be prepared for the possibility. > > > > Does that come close to answering your question? > > > > > Regards, > > > > > Scott > > > > Jon Cast > > _______________________________________________ > > Haskell-Cafe mailing list > > [EMAIL PROTECTED] > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > _______________________________________________ > Haskell-Cafe mailing list > [EMAIL PROTECTED] > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
