On Tue, Aug 9, 2016 at 2:20 PM, John Clements <cleme...@brinckerhoff.org> 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 racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
