"Bill Page" <[EMAIL PROTECTED]> writes: | On Fri, May 16, 2008 at 11:26 AM, Gabriel Dos Reis <[EMAIL PROTECTED]> wrote: | > "Bill Page" <[EMAIL PROTECTED]> writes: | > | > | On Fri, May 16, 2008 at 9:10 AM, Gabriel Dos Reis wrote: | > | > | > | > Well, my understanding of your proposal was that in | > | > | > | > if cond then | > | > x := 1 | > | > else | > | > x := 2.3 | > | > ... | > | > the compiler would assign type Integer to `x' in the `then' branch, | > | > and type Float in the `else' branch, and type Union(Integer,Float) at | > | > the meet point. | > | | > | No. I think *you* suggested that as an option in an earlier email. | > | That was not my idea. | > | > My other suggestion (which I repeatedly said I was not proposing as | > actual semantics, but only to point that the design space is large) | > was a `real' overload of variables. Not unions. | > | | In | | http://sourceforge.net/mailarchive/message.php?msg_id=873aokc3f8.fsf%40gauss.cs.tamu.edu | | you wrote: | | "In the current semantics, branches of if-statements do not have their | own scopes, so the meet environment of an if-statement is the union of ^^^^^^^^^^^^^^ | environment of both branches. And this is where the error comes in: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | One cannot declared the same variable in the same environment with | different modes." | | By this I understood you to be talking literally about the type | 'Union', although now with further explanation I understand that you | were probably thinking about the compiler "environment" in a somewhat | different way. But from your comment this solution seems obvious.
Gosh, you've picked my curiosity :-) I literally wrote environment. :-/ How could that have been _probably_ something else in a somewhat different way when I was talking about the compiler, environment, the meet environement, and concluding with the impossibility of declaring the same variable with different modes? The solution may be obvious (as I thought) but it turns out to draw a barrage. Anyway, I've fixed the semantic errors in the algebra, and I will implement the scope for if-statement later when I'm done with more pressing issues. -- Gaby ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ open-axiom-devel mailing list open-axiom-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open-axiom-devel
