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Re: [Chicken-users] bug using syntax-case in load'ed files

From: felix winkelmann
Subject: Re: [Chicken-users] bug using syntax-case in load'ed files
Date: Mon, 23 Oct 2006 23:46:39 +0200

On 10/23/06, Alejandro Forero Cuervo <address@hidden> wrote:
This is just to report a bug I found in the syntax-case egg.  I hope
it is not a misundertanding on my case.

If I run csi and eval

    (use html-stream syntax-case srfi-40)
    (stream-cons "foo" stream-null)

I get

    Error: unbound variable: stream-cons .

I tested under Chicken 2.5.  Interestingly, if I change the order and
put syntax-case first (or if I remove html-stream), the second
expression evaluates successfully.

This is related to what Andreas reported (the macro-expander gets
replaced while compiling and loading separate files), so let me
put the basic problem and the way to approach this in different

Chicken supports two different languages: one is a fairly R5RS-
compliant Scheme and uses a low-level "defmacro"-style macro system.
Another is a somewhat more R5RS-compliant Scheme with
syntax-case and a version of "define-macro" that is built on top
of syntax-case (Actually there are many more languages and macro-expanders, but
lets consider them at another time).

So I recommend to chose whatever language suits you best
and stick to it, throughout all your source-files, preferably keeping
it out of the source completely (by compiling/interpreting with "-R
It is very error-prone to mix high-level and low-level macros and
loading code at run-time or using "include" in the wrong place can
lead to very confusing behaviour.
An exception to the one-language-for-all-rule is when you want to use
functionality that is only available in one macro system (say, sxml-match).
In that case, put the use into a separate compilation unit and thus
avoid mixing up the compile/expansion-time environment. Scheme systems
like PLT or Scheme48 have funky module systems to handle this, chicken
does it more like C does, by using batch-compiled compilation units.

Sorry, I have no quick-and-easy fix for this.



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