On Tue, Aug 9, 2016 at 2:20 PM, John Clements <[email protected]> wrote:
> > Racket is essentially a lexically scoped language. That is: it should be > possible to look at a piece of code and figure out where the binding for a > given variable is. It does have a dynamic binding mechanism, but the names > that are bound dynamically … can be determined lexically. > > This might seem to prevent the kind of code that you’re talking about, but > Racket compensates for this with an extraordinarily flexible macro system, > and a very permissive notion of what exactly constitutes “compile-time.” > It’s certainly possible to dynamically generate a piece of code using > macros. Once generated, though, this piece of code is going to behave > dependably. > > How does this affect your particular example? Well, it’s extremely easy to > write a macro that does what you describe: > > #lang racket > > (define-syntax makefuns > (syntax-rules () > [(_ name ...) > (begin (define name (lambda () (displayln "foo"))) > ...)])) > > (makefuns x y z) > > (x) > > (y) > > (z) > > This solves the problem of creating top-level bindings at run time (more or less run time, anyway), but it doesn't handle the lexical closure part. Is there a way to do that? > Hope this helps, apologies for telling you anything that you already knew. > I actually knew none of that, so I appreciate the telling. :> Dave > > John > > > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
