[plt-scheme] A dummy syntax context

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Wed Sep 1 19:31:02 EDT 2004

At Wed, 1 Sep 2004 16:47:09 -0400, "Mike T. Machenry" wrote:
> I am trying to make a readable<%> snip% exapand to a define using an 
> identifier found within the snip%'s text%. To do this I a using 
> symbol->string on the contents of the text% and then datum->syntax-object 
> on the resultant symbol. The problem I am having, however, is that I need a 
> syntax context (color) for datum->syntax-object. Normally, one would just 
> use something like #'dummy for the context, however, being that the syntax 
> is an identifier being defined, drscheme complains with:
> define-values: identifier for a top-level definition already has a module 
> context in: foo
> Where foo is the symbol I am converting to a syntax-object and using in a 
> define.
> I am calling datum->syntax-object from within the module that provides my 
> snip, so it is getting that module's context. I don't know how to take the 
> context out of the syntax object.

Do you need a context for this particular identifier? Most identifiers
produced by `read' have no lexical context. In this case, it sounds
like you should use #f for the context argument to
`datum->syntax-object' so that the identifier will have no context.


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