Well it is a question that originated after studying the (mathematical)
strange typing for runST.
Besides runST I had no other specific problem in my mind and I thought if
it was possible to interrogate the typechecker to contol
(only in the compiler phase) the flow just as runST is in some sense doing.
But perhaps it is not possible in a statically typed language.
More about this will be clear in a forthcoming email that I am now preparing
titled "About the abuse of frall in Haskell"
Friendly
Jan Brosius
> Tue, 2 May 2000 10:14:40 +0200, Jan Brosius <[EMAIL PROTECTED]> pisze:
>
> > Suppose in some function definition some variable is of type A s a and
I
> > want to do something like this : if the type variable of the first
parameter
> > in A s a
> > is s then do this if not then do something else.
>
> This is what classes are for, even if not exactly in the way you mean.
>
> This is a complex subject: they are powerful, but many things that
> seem to be almost possible cannot be done with them, and there are
> many extensions to Haskell related to classes.
>
> Remember that there is no "else". Everything must be positive.
> And it must fit into the statically typed world.
>
> Tell us what the specific problem is. Maybe some completely different
> approach would be reasonable for it.
>
> --
> __("< Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
> \__/ GCS/M d- s+:-- a23 C+++$ UL++>++++$ P+++ L++>++++$ E-
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> QRCZAK 5? X- R tv-- b+>++ DI D- G+ e>++++ h! r--%>++ y-
>
>
>
