<html> <head> <meta content="text/html; charset=UTF-8" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> On 05/21/2012 06:02 AM, Matthew Flatt wrote: <blockquote cite="mid:20120521120238.A7216650094@mail-svr1.cs.utah.edu" type="cite"> <pre wrap="">At Sun, 20 May 2012 22:42:30 -0600, Jon Rafkind wrote: </pre> <blockquote type="cite"> <pre wrap="">The issue is why do I have to use a name other than 'name' for the pattern variable on the line where it says 'HERE'. If I use the 'name' pattern variable then the syntax-parse form generated by 'make-transformer' will use the wrong lexical context for the literal set. I don't see how the lexical context of the outer 'name' differs from the inner 'new-name', other than the 'new-name' has an extra mark on it. </pre> </blockquote> <pre wrap=""> When you use `name' instead of `new-name', then `name' gets replaced by `x' from the use of `define-new-syntax', and `x' (unlike `name') has a different lexical context than `new-name'. </pre> </blockquote> I thought that too but while debugging it didn't seem to be the case. If I put a printf in the 'make-transformer' macro to "see" what name is being passed in then using 'name' or 'new-name' as the pattern variable results in the same thing being printed. <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <pre style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; word-wrap: break-word; white-space: pre-wrap; "> (begin-for-syntax (define-syntax (make-transformer stx) (syntax-parse stx [(_ name pattern template) (printf "Name is ~a\n" #'name) #'#'(lambda (stx) (syntax-parse stx #:literal-sets ([literals #:at name]) [pattern template]))]))) </pre> Then calling 'make-transformer' 3 different ways: <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <pre style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; word-wrap: break-word; white-space: pre-wrap; ">(lambda (stx) (syntax-parse stx [(_ new-name) (with-syntax ([output (make-transformer name pattern template)]) #'(define-syntax new-name output))] </pre> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> "Name is #<syntax:x.rkt:56:19 x>", where line 56 is the use-site of 'define-new-syntax' <pre style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; word-wrap: break-word; white-space: pre-wrap; ">(lambda (stx) (syntax-parse stx [(_ name) (with-syntax ([output (make-transformer name pattern template)]) #'(define-syntax name output))] </pre> "Name is #<syntax:x.rkt:56:19 x>" <pre style="color: rgb(0, 0, 0); font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; word-wrap: break-word; white-space: pre-wrap; ">(lambda (stx) (syntax-parse stx [(_ new-name) (with-syntax ([output (make-transformer new-name pattern template)]) ;; line 39 #'(define-syntax new-name output))] </pre> "Name is #<syntax:x.rkt:39:61 new-name>" It seems like the 2nd and 3rd cases should be similar in that the 2nd case should report #<syntax:x.rkt:39:61: x> as the source instead of the original x from the use-site. So given that there is a difference between the 1st and 2nd cases how can I "see" this? printf doesn't seem to be the right tool. </body> </html>