<html> <head> <style></style> </head> <body class='hmmessage'> > Date: Sun, 17 Jan 2010 18:42:32 +0000 > Subject: Re: [plt-scheme] Very basic macro question > From: noelwelsh@gmail.com > To: johnyseventy@hotmail.com > CC: plt-scheme@list.cs.brown.edu > > On Sun, Jan 17, 2010 at 2:22 PM, johny seventy <johnyseventy@hotmail.com> wrote: > > I understand why example > > four works but is there anyway I can do this without eval? > > A transformer binding and syntax-local-value. > > It doesn't make sense to parameterise a macro by a run-time value -- > macros are expanded before run-time so they cannot depend on run-time > values. > > N. Thanks for the responses. I just want to clarify one more thing. I have an sexpr which is created dynamically at runtime and I want to transform this sexpr. It seemed really easy to do the transformation using a syntax-rules macro. So the problem is I have missed the boat at this stage as macro expansion has already taken place. The only way I can see how to invoke the macro at this stage is by using eval. I am not sure what you mean by a transformer binding and syntax-local-value. Is there a simple example of this in action I could take a look at? Thanks for your patience. <hr />Not got a Hotmail account? <a href='http://clk.atdmt.com/UKM/go/197222280/direct/01/' target='_new'>Sign-up now - Free</a></body> </html>