From: David Kastrup <dak@gnu.org>
To: "Linus Björnstam" <linus.bjornstam@veryfast.biz>
Cc: guile-devel@gnu.org, Han-Wen Nienhuys <hanwenn@gmail.com>
Subject: Re: unhandled constant?
Date: Sat, 01 Feb 2020 15:23:12 +0100 [thread overview]
Message-ID: <877e16v12n.fsf@fencepost.gnu.org> (raw)
In-Reply-To: <f0e209a0-0709-4966-98aa-854d000c3046@www.fastmail.com> ("Linus Björnstam"'s message of "Sat, 01 Feb 2020 14:16:36 +0100")
Linus Björnstam <linus.bjornstam@veryfast.biz> writes:
> On Sat, 1 Feb 2020, at 12:09, David Kastrup wrote:
>>
>> Can you expand about the "expansion time and macro time separation"?
>>
>> If we have
>>
>> (define decl '())
>> (define (make-var n v) (list "var" n v))
>> (defmacro define-session (name value)
>> (define (inner n v)
>> (set! decl
>> (cons
>> (make-var n v)
>> decl))
>> )
>> `(,inner ',name ,value))
>> (define-session foo 1)
>> (display decl)
>> (newline)
>>
>> as stated, the local function "inner" is defined at macro time, but the
>> form
>> `(,inner ',name ,value)
>> does not export the _name_ inner but rather the defined function. That
>> part naively appears to me like it should work; an "expansion time and
>> macro time" issue appears rather to be that inner calls make-var (and
>> accesses decl) which is only being defined at expansion time.
>>
>> The error message, however, rather appears to complain about inner being
>> undefined rather than the definition of inner referring to undefined
>> entities.
>
>
> I am not sure what is really the problem. Either the inner function is
> not present at runtime due to separation of compile time and runtime,
> or it is a result of how defmacro re-introduces the result of the
> macro into the syntactic context of the macro usage (where inner is
> not visible). Either way, having the inner definition in the macro
> output will solve the problem of it not being visible.
This fails when byte-compiling, so it would appear that the equivalent
of
(defmacro ...
(define local-fun ...
`(,local-fun ...)))
is not able to represent the local (and thus ultimately anonymous)
function here. Whether this is a general shortcoming or is conditioned
on local-fun calling functions not available at byte-compile time (in
which case those would need to get wrapped in eval-and-expand) I haven't
checked yet.
--
David Kastrup
next prev parent reply other threads:[~2020-02-01 14:23 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 23:08 unhandled constant? Han-Wen Nienhuys
2020-01-29 15:06 ` Ricardo Wurmus
2020-01-30 8:05 ` Han-Wen Nienhuys
2020-01-31 10:49 ` Han-Wen Nienhuys
2020-01-31 11:17 ` Ricardo Wurmus
2020-02-02 19:30 ` Jan Nieuwenhuizen
2020-01-31 14:57 ` Linus Björnstam
2020-01-31 15:16 ` Han-Wen Nienhuys
2020-01-31 17:50 ` Han-Wen Nienhuys
2020-01-31 18:19 ` Linus Björnstam
2020-01-31 19:17 ` Han-Wen Nienhuys
2020-01-31 19:52 ` Linus Björnstam
2020-01-31 20:01 ` Linus Björnstam
2020-02-01 9:54 ` Han-Wen Nienhuys
2020-02-01 9:56 ` Han-Wen Nienhuys
2020-02-01 10:10 ` David Kastrup
2020-02-01 11:23 ` Han-Wen Nienhuys
2020-02-01 11:36 ` David Kastrup
2020-02-01 13:12 ` Linus Björnstam
2020-02-01 11:09 ` David Kastrup
2020-02-01 13:16 ` Linus Björnstam
2020-02-01 14:23 ` David Kastrup [this message]
2020-02-01 15:21 ` Linus Björnstam
2020-02-01 21:55 ` Taylan Kammer
2020-02-01 21:58 ` Fwd: " Taylan Kammer
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