Thanks Jay and Gary, I remember seeing something like this in an APL variant and it was one of the few features I didn't know how to translate into scheme.
Cheers, Paul Pereira On 23 February 2012 14:36, Jay McCarthy <[email protected]> wrote: > I think you should look at the Macro Stepper output for your failing > example, because you'll see that the code that references y appears in > the branch that doesn't have access to a y. You'd want to do something > in the macro to determine which function to compile to. > > Jay > > p.s. I'm glad you like super cut. =) > > On 2/22/12, Paul Pereira <[email protected]> wrote: >> I am new to macro writing and am trying to do the following: >> >> (fun body ...) >> => (lambda (x) body ...) >> or (lambda (x y) body ...) >> or (lambda (x y z) body ...) >> >> where x, y, z are taken from the scope of body. >> Right now, I am just trying to use case-lambda to switch between >> these. I guess I am trying for a much simpler version of scut ( >> https://github.com/jeapostrophe/exp/blob/master/scut.ss ), but I don't >> understand that macro yet. >> >> What I have so far does not work: >> >> (define-syntax (fun stx) >> (syntax-case stx () >> ((fun body rest ...) >> (with-syntax ((x (datum->syntax #'body 'x)) >> (y (datum->syntax #'body 'y)) >> (z (datum->syntax #'body 'z))) >> #'(case-lambda ((x) body rest ...) >> ((x y) body rest ...) >> ((x y z) body rest ...)))))) >> >> (map (fun x) '(1 2 3)) => '(1 2 3) ... ok >> (map (fun (+ x x)) '(1 2 3)) => '(2 4 6) ... ok >> (map (fun (+ x y)) '(1 2 3) '(1 2 3)) ... y is an unbound identifier >> >> Do you have any suggestions? Thanks! >> >> Paul >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users >> > > > -- > Jay McCarthy <[email protected]> > Assistant Professor / Brigham Young University > http://faculty.cs.byu.edu/~jay > > "The glory of God is Intelligence" - D&C 93 ____________________ Racket Users list: http://lists.racket-lang.org/users
