define-macro syntax error

define-macro syntax error

[Akop Pogosian]

I am having problems getting simple define-macro to work in Guile 2.

For example, this:

(define-macro when
  (lambda (test . branch)
    `(if ,test
         (begin ,@branch))))

will give an error:

While compiling expression:
ERROR: Syntax error:
unknown file:8:0: source expression failed to match any pattern in form (define\
-macro when (lambda (test . branch) (quasiquote (if (unquote test) (begin (unqu\
ote-splicing branch))))))


What's wrong here?

Re: define-macro syntax error

[Daniel Hartwig]

On 12 February 2013 16:15, Akop Pogosian <apogosian@gmail.com> wrote:
> I am having problems getting simple define-macro to work in Guile 2.
>
> For example, this:
>
> (define-macro when
>   (lambda (test . branch)
>     `(if ,test
>          (begin ,@branch))))

> What's wrong here?
>

This is not the right syntax.  From the manual:

> (define-macro (NAME ARGS ...) BODY ...)

so, in your case:

(define-macro (when test . branch)
  `(if ,test
       (begin ,@branch)))

Regards

Re: define-macro syntax error

[Andy Wingo]

On Tue 12 Feb 2013 09:15, Akop Pogosian <apogosian@gmail.com> writes:

> (define-macro when
>   (lambda (test . branch)
>     `(if ,test
>          (begin ,@branch))))
>
> will give an error:

This is a bug.  I just fixed it in stable-2.0; thanks for the report.

In the meantime, you can use:

  (define-macro (when test . branch)
    ...)

Sorry for the inconvenience.

Andy
-- 
http://wingolog.org/

Re: define-macro syntax error

[Daniel Hartwig]

On 12 February 2013 16:42, Andy Wingo <wingo@pobox.com> wrote:
> On Tue 12 Feb 2013 09:15, Akop Pogosian <apogosian@gmail.com> writes:
>
>> (define-macro when
>>   (lambda (test . branch)
>>     `(if ,test
>>          (begin ,@branch))))
>>
>> will give an error:
>
> This is a bug.  I just fixed it in stable-2.0; thanks for the report.

Curious.  Is that some syntax from an older version, or …?

Re: define-macro syntax error

[Akop Pogosian]

On Tue, Feb 12, 2013 at 3:26 AM, Daniel Hartwig <mandyke@gmail.com> wrote:
> On 12 February 2013 16:42, Andy Wingo <wingo@pobox.com> wrote:
>> On Tue 12 Feb 2013 09:15, Akop Pogosian <apogosian@gmail.com> writes:
>>
>>> (define-macro when
>>>   (lambda (test . branch)
>>>     `(if ,test
>>>          (begin ,@branch))))
>>>
>>> will give an error:
>>
>> This is a bug.  I just fixed it in stable-2.0; thanks for the report.
>
> Curious.  Is that some syntax from an older version, or …?
>

I was testing examples from "Teach Yourself Scheme in Fixnum Days".
This is the format it uses.


-Akop

Re: define-macro syntax error

[Andy Wingo]

On Tue 12 Feb 2013 10:26, Daniel Hartwig <mandyke@gmail.com> writes:

> On 12 February 2013 16:42, Andy Wingo <wingo@pobox.com> wrote:
>> On Tue 12 Feb 2013 09:15, Akop Pogosian <apogosian@gmail.com> writes:
>>
>>> (define-macro when
>>>   (lambda (test . branch)
>>>     `(if ,test
>>>          (begin ,@branch))))
>>>
>>> will give an error:
>>
>> This is a bug.  I just fixed it in stable-2.0; thanks for the report.
>
> Curious.  Is that some syntax from an older version, or …?

It was supported in 1.8.

Andy
-- 
http://wingolog.org/

Re: define-macro syntax error

[Ian Price]

Akop Pogosian <apogosian@gmail.com> writes:

> (define-macro when
>   (lambda (test . branch)
>     `(if ,test
>          (begin ,@branch))))

FWIW, `when' is already available in Guile 2, and define-macro is
generally frowned upon. For these ultra-simple cases, prefer
define-syntax-rule.

-- 
Ian Price -- shift-reset.com

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"