Re: Change defaults of 'define-record-type*' need invalidate auto-compilation caches

[iyzsong@member.fsf.org (宋文武)]

ludo@gnu.org (Ludovic Courtès) writes:

> Hi!
>
> iyzsong@member.fsf.org (宋文武) skribis:
>
>> [...]
>>
>> Only with '--fresh-auto-compile' or delete the cache of x.scm, I will
>> get the output "y".
>>
>> Is this a bug?
>
> It’s a feature.  :-)
>
> Namely, default value resolution happens at macro-expansion time:
>
> scheme@(guile-user)> ,use(guix records)
> scheme@(guile-user)> (define-record-type* <foo>
>   foo make-foo foo?
>   (x foo-x (default "x")))
>
> scheme@(guile-user)> ,expand (foo)
> $2 = (let* ((x "x")
>        (s ((@@ (srfi srfi-9) allocate-struct) <foo> 1)))
>   ((@@ (srfi srfi-9) struct-set!) s 0 x)
>   s)
>
> That way, we can check at macro-expansion time that all the required
> fields are present, which is nice.
>
> The downside is what you write: that everything that uses the record
> type must be recompiled when it is changed (IOW, the record type is part
> of the ABI).
>
> HTH!

Get it, thanks for the explanation!