<!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 6.00.6000.16640" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face="Courier New" size=2>Consider:</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>#lang scheme</FONT></DIV> <DIV><FONT face="Courier New" size=2>(require (for-syntax some-library)) ; exports procedure F : string ... --> procedure</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(define-syntax (do-at-compile-time-only stx)</FONT></DIV> <DIV><FONT face="Courier New" size=2> (syntax-case stx ( )</FONT></DIV> <DIV><FONT face="Courier New" size=2>  ((_ name . list-of-strings)</FONT></DIV> <DIV><FONT face="Courier New" size=2>   (let ((list-of-strings (syntax->datum (syntax list-of-strings))))</FONT></DIV> <DIV><FONT face="Courier New" size=2>    (if (andmap string? list-of-strings)</FONT></DIV> <DIV><FONT face="Courier New" size=2>     (quasiquote-syntax</FONT></DIV> <DIV><FONT face="Courier New" size=2>      (define name</FONT></DIV> <DIV><FONT face="Courier New" size=2>       (unquote-syntax</FONT></DIV> <DIV><FONT face="Courier New" size=2>        (apply F list-of-strings))))</FONT></DIV> <DIV><FONT face="Courier New" size=2>     (raise-syntax-error etc))))))</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(provide do-at-compile-time-only)</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>Require the above module</FONT></DIV> <DIV><FONT face="Courier New" size=2>(do-at-compile-time-only f "string" ...)</FONT></DIV> <DIV><FONT face="Courier New" size=2>(f arg ...) </FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>I did some tests with this. It seems to work alright, but I cannot find it as a documented feature, which makes me suspicious. Can it be trusted? </FONT><FONT face="Courier New" size=2>Of course syntax do-at-compile-time-only must be given string-constants. It does not accept exprs that evaluate to strings. </FONT><FONT face="Courier New" size=2>For a simple procedure F, simply writing (define f (F "string" ...)) may be optimized such as to evaluate (F "string" ...) once only at compile time. I don't know whether or not the optimizer does do such things, but anyway I'm afraid my F is too complicated for the optimizer such as to detect that (F "string" ...) is in fact a constant across various run times and threads. The whole idea is to apply F once during compilation in order that there is no need to call F during every run time.</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>Kind regars, Jos</FONT></DIV></BODY></HTML>