Re: [racket-users] Strip the lexical context from an identifier
The `syntax-local-introduce` solution breaks when the macro is used from a different module. The datum->syntax solution may or may not have the behavior you are looking for: #lang racket (module a racket (require (for-syntax syntax/parse)) (require (for-syntax racket/syntax)) (define x 'a) (define-syntax (my-macro stx) (syntax-parse stx [(_ x:id) #:with a #'a #:with y (datum->syntax #'a (syntax-e #'x)) #`(lambda (a b) y)])) (provide my-macro)) (require 'a) ; These work ((my-macro a) 1 2) ; => 1 ((my-macro b) 1 2) ; => 2 ; Is this what you want? (define x 'b) ((my-macro x) 1 2) ; => 'a Notice that references are resolved in the complete environment of the macro definition site, and not only to names bound in the macro-generated template. An alternative approach would be to have the macro unhygienicially introduce the *bindings* a and b. The effect is different: #lang racket (module a racket (require (for-syntax syntax/parse)) (require (for-syntax racket/syntax)) (define-syntax (my-macro stx) (syntax-parse stx [(_ x:id) #:with a (datum->syntax this-syntax 'a) #:with b (datum->syntax this-syntax 'b) #`(lambda (a b) x)])) (provide my-macro)) (require 'a) ; These work ((my-macro a) 1 2) ; => 1 ((my-macro b) 1 2) ; => 2 ; Is this what you want? (define x 'b) ((my-macro x) 1 2) ; => 'b On Saturday, February 23, 2019 at 8:22:57 AM UTC-5, Stefano Lande wrote: > > Thanks to both of you, it is exactly what I was trying to do. > > Stefano > > Il giorno ven 22 feb 2019 alle ore 18:37 Matthias Felleisen < > matt...@felleisen.org > ha scritto: > >> >> And that’s better of course because you pick up the lexical scope, which >> >> (let ([x 4]) [(my-macro x) 1 2]) >> >> shows. >> >> >> >> > On Feb 22, 2019, at 1:26 PM, Sam Caldwell > > wrote: >> > >> > You can also do this with syntax-local-introduce to remove x's use-site >> scope*: >> > >> > #lang racket >> > >> > (require (for-syntax syntax/parse)) >> > >> > (define-syntax (my-macro stx) >> >(syntax-parse stx >> > [(_ x:id) >> > #:with x- (syntax-local-introduce #'x) >> > #'(lambda (a b) x-)])) >> > >> > ((my-macro a) 1 2) >> > ;; 1 >> > >> > ((my-macro b) 1 2) >> > ;; 2 >> > >> > (define x 3) >> > ((my-macro x) 1 2) >> > ;; 3 >> > >> > >> > >> > -Sam >> > >> > * well, I think that's what's going on. >> > >> > On Fri, Feb 22, 2019 at 1:21 PM Matthias Felleisen < >> matt...@felleisen.org > wrote: >> > >> > >> > > On Feb 22, 2019, at 1:08 PM, Stefano Lande > > wrote: >> > > >> > > Dear all, >> > > >> > > first of all, I might being misusing the terminology. Sorry about it. >> > > >> > > I would like to write a macro that gets an identifier and return its >> value in the new lexical scope created by the macro. >> > > For example: >> > > >> > > > (define-syntax (my-macro stx) >> > >(syntax-parse stx >> > > [(_ x:id) #'(lambda (a b) x) ])) >> > > >> > > >> > > > ((my-macro a) 1 2) >> > > 1 >> > > >> > > >((my-macro b) 1 2) >> > > 2 >> > > >> > > >> > > >> > > my-macro as above of course would not work. Is possible to receive an >> identifier, strip the lexical context, and evaluate it in the context of >> (lambda (a b) body) ? >> > >> > >> > Here is one way to get your macro: >> > >> > #lang racket >> > >> > (require (for-syntax syntax/parse)) >> > (require (for-syntax racket/syntax)) >> > >> > (define-syntax (my-macro stx) >> > (syntax-parse stx >> > [(_ x:id) >> > #:with a #'a >> > #:with y (datum->syntax #'a (syntax-e #'x)) >> > #`(lambda (a b) y)])) >> > >> > [(my-macro a) 1 2] >> > [(my-macro b) 1 2] >> > (define x 3) >> > [(my-macro x) 1 2] >> > >> > -- >> > 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...@googlegroups.com . >> > For more options, visit https://groups.google.com/d/optout. >> >> -- 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.
Re: [racket-users] Strip the lexical context from an identifier
Thanks to both of you, it is exactly what I was trying to do. Stefano Il giorno ven 22 feb 2019 alle ore 18:37 Matthias Felleisen < matth...@felleisen.org> ha scritto: > > And that’s better of course because you pick up the lexical scope, which > > (let ([x 4]) [(my-macro x) 1 2]) > > shows. > > > > > On Feb 22, 2019, at 1:26 PM, Sam Caldwell wrote: > > > > You can also do this with syntax-local-introduce to remove x's use-site > scope*: > > > > #lang racket > > > > (require (for-syntax syntax/parse)) > > > > (define-syntax (my-macro stx) > >(syntax-parse stx > > [(_ x:id) > > #:with x- (syntax-local-introduce #'x) > > #'(lambda (a b) x-)])) > > > > ((my-macro a) 1 2) > > ;; 1 > > > > ((my-macro b) 1 2) > > ;; 2 > > > > (define x 3) > > ((my-macro x) 1 2) > > ;; 3 > > > > > > > > -Sam > > > > * well, I think that's what's going on. > > > > On Fri, Feb 22, 2019 at 1:21 PM Matthias Felleisen < > matth...@felleisen.org> wrote: > > > > > > > On Feb 22, 2019, at 1:08 PM, Stefano Lande wrote: > > > > > > Dear all, > > > > > > first of all, I might being misusing the terminology. Sorry about it. > > > > > > I would like to write a macro that gets an identifier and return its > value in the new lexical scope created by the macro. > > > For example: > > > > > > > (define-syntax (my-macro stx) > > >(syntax-parse stx > > > [(_ x:id) #'(lambda (a b) x) ])) > > > > > > > > > > ((my-macro a) 1 2) > > > 1 > > > > > > >((my-macro b) 1 2) > > > 2 > > > > > > > > > > > > my-macro as above of course would not work. Is possible to receive an > identifier, strip the lexical context, and evaluate it in the context of > (lambda (a b) body) ? > > > > > > Here is one way to get your macro: > > > > #lang racket > > > > (require (for-syntax syntax/parse)) > > (require (for-syntax racket/syntax)) > > > > (define-syntax (my-macro stx) > > (syntax-parse stx > > [(_ x:id) > > #:with a #'a > > #:with y (datum->syntax #'a (syntax-e #'x)) > > #`(lambda (a b) y)])) > > > > [(my-macro a) 1 2] > > [(my-macro b) 1 2] > > (define x 3) > > [(my-macro x) 1 2] > > > > -- > > 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. > > -- 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.
Re: [racket-users] Strip the lexical context from an identifier
And that’s better of course because you pick up the lexical scope, which (let ([x 4]) [(my-macro x) 1 2]) shows. > On Feb 22, 2019, at 1:26 PM, Sam Caldwell wrote: > > You can also do this with syntax-local-introduce to remove x's use-site > scope*: > > #lang racket > > (require (for-syntax syntax/parse)) > > (define-syntax (my-macro stx) >(syntax-parse stx > [(_ x:id) > #:with x- (syntax-local-introduce #'x) > #'(lambda (a b) x-)])) > > ((my-macro a) 1 2) > ;; 1 > > ((my-macro b) 1 2) > ;; 2 > > (define x 3) > ((my-macro x) 1 2) > ;; 3 > > > > -Sam > > * well, I think that's what's going on. > > On Fri, Feb 22, 2019 at 1:21 PM Matthias Felleisen > wrote: > > > > On Feb 22, 2019, at 1:08 PM, Stefano Lande wrote: > > > > Dear all, > > > > first of all, I might being misusing the terminology. Sorry about it. > > > > I would like to write a macro that gets an identifier and return its value > > in the new lexical scope created by the macro. > > For example: > > > > > (define-syntax (my-macro stx) > >(syntax-parse stx > > [(_ x:id) #'(lambda (a b) x) ])) > > > > > > > ((my-macro a) 1 2) > > 1 > > > > >((my-macro b) 1 2) > > 2 > > > > > > > > my-macro as above of course would not work. Is possible to receive an > > identifier, strip the lexical context, and evaluate it in the context of > > (lambda (a b) body) ? > > > Here is one way to get your macro: > > #lang racket > > (require (for-syntax syntax/parse)) > (require (for-syntax racket/syntax)) > > (define-syntax (my-macro stx) > (syntax-parse stx > [(_ x:id) > #:with a #'a > #:with y (datum->syntax #'a (syntax-e #'x)) > #`(lambda (a b) y)])) > > [(my-macro a) 1 2] > [(my-macro b) 1 2] > (define x 3) > [(my-macro x) 1 2] > > -- > 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. -- 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.
Re: [racket-users] Strip the lexical context from an identifier
You can also do this with syntax-local-introduce to remove x's use-site scope*: #lang racket (require (for-syntax syntax/parse)) (define-syntax (my-macro stx) (syntax-parse stx [(_ x:id) #:with x- (syntax-local-introduce #'x) #'(lambda (a b) x-)])) ((my-macro a) 1 2) ;; 1 ((my-macro b) 1 2) ;; 2 (define x 3) ((my-macro x) 1 2) ;; 3 -Sam * well, I think that's what's going on. On Fri, Feb 22, 2019 at 1:21 PM Matthias Felleisen wrote: > > > > On Feb 22, 2019, at 1:08 PM, Stefano Lande wrote: > > > > Dear all, > > > > first of all, I might being misusing the terminology. Sorry about it. > > > > I would like to write a macro that gets an identifier and return its > value in the new lexical scope created by the macro. > > For example: > > > > > (define-syntax (my-macro stx) > >(syntax-parse stx > > [(_ x:id) #'(lambda (a b) x) ])) > > > > > > > ((my-macro a) 1 2) > > 1 > > > > >((my-macro b) 1 2) > > 2 > > > > > > > > my-macro as above of course would not work. Is possible to receive an > identifier, strip the lexical context, and evaluate it in the context of > (lambda (a b) body) ? > > > Here is one way to get your macro: > > #lang racket > > (require (for-syntax syntax/parse)) > (require (for-syntax racket/syntax)) > > (define-syntax (my-macro stx) > (syntax-parse stx > [(_ x:id) > #:with a #'a > #:with y (datum->syntax #'a (syntax-e #'x)) > #`(lambda (a b) y)])) > > [(my-macro a) 1 2] > [(my-macro b) 1 2] > (define x 3) > [(my-macro x) 1 2] > > -- > 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. > -- 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.
Re: [racket-users] Strip the lexical context from an identifier
> On Feb 22, 2019, at 1:08 PM, Stefano Lande wrote: > > Dear all, > > first of all, I might being misusing the terminology. Sorry about it. > > I would like to write a macro that gets an identifier and return its value in > the new lexical scope created by the macro. > For example: > > > (define-syntax (my-macro stx) >(syntax-parse stx > [(_ x:id) #'(lambda (a b) x) ])) > > > > ((my-macro a) 1 2) > 1 > > >((my-macro b) 1 2) > 2 > > > > my-macro as above of course would not work. Is possible to receive an > identifier, strip the lexical context, and evaluate it in the context of > (lambda (a b) body) ? Here is one way to get your macro: #lang racket (require (for-syntax syntax/parse)) (require (for-syntax racket/syntax)) (define-syntax (my-macro stx) (syntax-parse stx [(_ x:id) #:with a #'a #:with y (datum->syntax #'a (syntax-e #'x)) #`(lambda (a b) y)])) [(my-macro a) 1 2] [(my-macro b) 1 2] (define x 3) [(my-macro x) 1 2] -- 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.
[racket-users] Strip the lexical context from an identifier
Dear all, first of all, I might being misusing the terminology. Sorry about it. I would like to write a macro that gets an identifier and return its value in the new lexical scope created by the macro. For example: > (define-syntax (my-macro stx) (syntax-parse stx [(_ x:id) #'(lambda (a b) x) ])) > ((my-macro a) 1 2) 1 >((my-macro b) 1 2) 2 my-macro as above of course would not work. Is possible to receive an identifier, strip the lexical context, and evaluate it in the context of (lambda (a b) body) ? Best, Stefano -- 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.
