zimoun <zimon.touto...@gmail.com> writes: > Hi, > > On Mon, 25 Oct 2021 at 02:15, Joshua Branson via Bug reports for GNU Guix > <bug-guix@gnu.org> wrote: > >> So I made a pretty noobie-like mistake a few minutes ago. When one >> tries to make a (record-configuration), he invariably create an >> infinite number of records. The guile compiler eventually runs out >> of memory and stops compiling. >> >> (use-modules (guix records)) >> >> (define-record-type* <record-configuration> >> record-configuration make-record-configuration >> record-configuration? >> (command record-configuration-command >> ;; the error is here is on the next line >> (default (record-configuration)))) >> >> (record-configuration) > > This <record-configuration> is defined by creating recursively another > instance. Thus, It is expected that it does not work, no?
Yes that is correct. I am only slightly annoyed at the lack of a helpful error message. Thanks for helping me clarify my point. I was working on a rather large collection of guix records for an opensmtpd service configuration. The file is about 1,000 lines long. Trying to find that error without a helpful error message was slightly annoying. I agree that the fault was mine and I do not believe the bug can be fixed. Rather it would be nice to have a more helpful error message. It could be possible that guile offers such flexibility in general that the compiler is unable to provide good error messages in all situations. I am just hoping for a better error message somewhere, ether in the compiler or something in the (define-syntax-record* macro. Is it possible to get a better error message? Is that a thing worth pursuing? Or is the fix worse than the present condition? > Reading the doc, > > 1. what do you want to achieve? > 2. what does it appear to you buggy? Or what do you think the > “correct” behaviour should be? > > (define-syntax define-record-type* > (lambda (s) > "Define the given record type such that an additional \"syntactic > constructor\" is defined, which allows instances to be constructed with named > field initializers, à la SRFI-35, as well as default values. An example use > may look like this: > > (define-record-type* <thing> thing make-thing > thing? > this-thing > (name thing-name (default \"chbouib\")) > (port thing-port > (default (current-output-port)) (thunked)) > (loc thing-location (innate) (default (current-source-location)))) > > This example defines a macro 'thing' that can be used to instantiate records > of this type: > > (thing > (name \"foo\") > (port (current-error-port))) > > The value of 'name' or 'port' could as well be omitted, in which case the > default value specified in the 'define-record-type*' form is used: > > (thing) > > The 'port' field is \"thunked\", meaning that calls like '(thing-port x)' will > actually compute the field's value in the current dynamic extent, which is > useful when referring to fluids in a field's value. Furthermore, that thunk > can access the record it belongs to via the 'this-thing' identifier. > > A field can also be marked as \"delayed\" instead of \"thunked\", in which > case its value is effectively wrapped in a (delay …) form. > > A field can also have an associated \"sanitizer\", which is a procedure that > takes a user-supplied field value and returns a \"sanitized\" value for the > field: > > (define-record-type* <thing> thing make-thing > thing? > this-thing > (name thing-name > (sanitize (lambda (value) > (cond ((string? value) value) > ((symbol? value) (symbol->string value)) > (else (throw 'bad! value))))))) > > It is possible to copy an object 'x' created with 'thing' like this: > > (thing (inherit x) (name \"bar\")) > > This expression returns a new object equal to 'x' except for its 'name' > field and its 'loc' field---the latter is marked as \"innate\", so it is not > inherited." > > > (Argh, I do not know how to read/display the docstring from the REPL, > another annoying* story. :-)) Do you know if the above guix records are in the guix manual? If not, I'll probably add them. > >> This is not possible with (srfi sfri-9) >> >> (use-modules (srfi srfi-9)) >> >> (define-record-type <employee> >> (make-employee name age (make-employeee 5 5 5)) >> employee? >> (name employee-name) >> (age employee-age set-employee-age!) >> (salary employee-salary set-employee-salary!)) > > Well, ’(guix records)’ allows to do more than ’(srfi srfi-9)’. Amen for that! (guix records) are awesome! > Aside, I > am not convinced that this latter snippet is similar than the former > previous one. I was just trying to see if I could produce a similar issue for the guile compiler via only using (srfi srfi-9). Apparently I cannot. > Cheers, > simon > > *annoying REPL, I get: > > scheme@(guix-user)> ,describe define-record-type* > While executing meta-command: > Syntax error: > unknown file:79:10: source expression failed to match any pattern in form > define-record-type* try (use-modules (guix records))...though you probably already did that. What about ,m (guix records) ? -- Joshua Branson (jab in #guix) Sent from Emacs and Gnus https://gnucode.me https://video.hardlimit.com/accounts/joshua_branson/video-channels https://propernaming.org "You can have whatever you want, as long as you help enough other people get what they want." - Zig Ziglar
