Re: sending and and or as an argument links their behavior

[Gregory Marton]

> `or' and `and' are macros, and it doesn't work to pass them as
> procedure arguments.
>
> I forget for the moment what R5RS says; I suspect the above is not
> allowed, and so perhaps Guile should detect it and report an error.
>
> The detailed reason for this is Guile's memoization - but that's not
> really the main point.

If guile will continue to behave this way, then yes, reporting an error 
would save some pain.  As a user, I would much prefer to view it as a bug, 
because I don't want to have to care whether something like (and...) is 
implemented as a macro or as a procedure.  This may be hopelessly naive.


I tried to find the part of R5RS that defines this behavior.  Section 4.3 
talks about keywords binding to macro transformers in a very different way 
than it talks about variables binding to values in 4.1.1, as if it is 
licensing a separate namespace, reminiscent of Lisp's function and data 
namespaces (except that a single identifier may only mean one at a time). 
Section 7.1.3 makes explicit that procedure calls are different from macro 
uses, which are (<keyword> <datum>*), not (<operator> <operand>*), 
consistent with the above.  This looks to the untrained eye like a wart.

In contrast, the guile docs on Procedures and Macros talk about macros as 
first class things: "when a symbol defined to this value appears as the 
first symbol in an expression", which makes me think I can define a symbol 
to that value, pass it around, and expect it to work as the first symbol in 
an s-expression.  I see that "pass it around" is never made explicit, but 
it would certainly be consistent, and partly The Way Things Are.  I hope 
that a memoization bug won't kill this bit of beauty.

I apologise if I badly misunderstood something.  I am a novice here, and 
speak only as a relatively recent user, curious to learn more.

Thanks,
Grem

--
------ __@   Gregory A. Marton                http://csail.mit.edu/~gremio/
--- _`\<,_                                                                .
-- (*)/ (*)                Oh Lord, give me patience... NOW!
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