<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=iso-8859-1"> <META content="MSHTML 6.00.6000.16481" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face=ti>Say I have a module with an option for its tuning. This option will be used both in the transformer and in the run time environment. For example:</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(module a mzscheme<BR>;option used both in transformer and run time environment<BR> (define-for-syntax option 1)<BR> (define option 1)<BR>;-----------------<BR> (define-syntax macro-a<BR>  (case option<BR>   ((1) (lambda (stx) #'"the option is 1"))<BR>   (else (lambda (stx) #'"the option is not 1"))))<BR> (define proc-a<BR>  (case option<BR>   ((1)  (lambda () "the option is 1"))<BR>   (else (lambda () "the option is not 1"))))<BR> (provide macro-a proc-a))<BR>(require a)<BR>(macro-a) ; --> "the option is 1"<BR>(proc-a)  ; --> "the option is 1"</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face=tim>However, I dont find it elegant to have two definitions for conceptually the same option. The standard solution would be:</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(module option mzscheme<BR> (define option 1)<BR> (provide option))</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(module b mzscheme<BR>;option used both in transformer and run time environment<BR> (require-for-syntax option)<BR> (require option)<BR>;-----------------<BR> (define-syntax macro-b<BR>  (case option<BR>   ((1) (lambda (stx) #'"the option is 1"))<BR>   (else (lambda (stx) #'"the option is not 1"))))<BR> (define proc-b<BR>  (case option<BR>   ((1)  (lambda () "the option is 1"))<BR>   (else (lambda () "the option is not 1"))))<BR> (provide macro-b proc-b))<BR>(require b)<BR>(macro-b) ; --> "the option is 1"<BR>(proc-b)  ; --> "the option is 1" </FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face=tim>But now the definition of the option is separated from the module, which I dont like too much. So I came up with the following.</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(module c mzscheme<BR>;option used both in transformer and run time environment<BR> (define-for-syntax option 2)<BR> (define-syntax (transfer stx)<BR>  (syntax-local-introduce #`(define option (#%datum . #,option))))<BR> (transfer)<BR>;--------------------------------------------------------<BR> (define-syntax macro-c<BR>  (case option<BR>   ((1)  (lambda (stx) #'"the option is 1"))<BR>   (else (lambda (stx) #'"the option is not 1"))))<BR> (define proc-c<BR>  (case option<BR>   ((1)  (lambda () "the option is 1"))<BR>   (else (lambda () "the option is not 1"))))<BR> (provide macro-c proc-c))<BR>(require c)<BR>(macro-c) ; --> "the option is not 1"<BR>(proc-c)  ; --> "the option is not 1"</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face=tim>This seems to do what I want, but it seems a little bit tricky too. Can I trust the approach in module c, or is the approach in modules a and b safer?</FONT><FONT face=tim><BR>Best wishes, Jos koot.</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><BR><FONT face="Courier New" size=2></FONT> </DIV></BODY></HTML>