Re: [PATCH] Move ambitus print callback to scheme
Carl Sorensen writes: > On 8/28/09 10:56 PM, "David Kastrup" wrote: > >> Carl Sorensen writes: >> >>> On Aug 28, 2009, at 1:16 PM, "Nicolas Sceaux" >>> wrote: >>> According to R5RS, it is an error to modify a literal list. If a function returns '(), the caller won't be allowed to apply a modifying function on the result (eg. append!) >>> >>> IIUC, '() is not a literal list, but a constant that represents the >>> empty list. >> >> It is a literal list in my opinion, but one that happens to have no >> unique and/or modifiable conses. Append will work just fine on it. > > It is *not* a literal list. > > Here is the proof: > > guile> (define a '(4 5)) > guile> (define b '(4 5)) > guile> (eq? a b) > #f > guile> (define c '()) > guile> (define d '()) > guile> (eq? c d) > #t > > > '(4 5) is a literal list, and thus a is not eq? to b, although it is equal? > to b Huh? What kind of argument is that supposed to be? (define a 4) (define b 4) (eq? a b) Would you claim that 4 is not a literal integer? '() is literal (namely explicitly specified) and it is a list (namely a cons or nil). '() is not a literal _cons_, and it is not unique. But it certainly is literal (a spelled out value) and a list. > On the other hand, c is eq? to d, because '() is a constant, and both c and > d are set to the same constant. I think you are just confused about the meaning of "literal". -- David Kastrup ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
On 8/28/09 10:56 PM, "David Kastrup" wrote: > Carl Sorensen writes: > >> On Aug 28, 2009, at 1:16 PM, "Nicolas Sceaux" >> wrote: >> >>> >>> According to R5RS, it is an error to modify a literal list. >>> If a function returns '(), the caller won't be allowed to >>> apply a modifying function on the result (eg. append!) >>> >> >> IIUC, '() is not a literal list, but a constant that represents the >> empty list. > > It is a literal list in my opinion, but one that happens to have no > unique and/or modifiable conses. Append will work just fine on it. It is *not* a literal list. Here is the proof: guile> (define a '(4 5)) guile> (define b '(4 5)) guile> (eq? a b) #f guile> (define c '()) guile> (define d '()) guile> (eq? c d) #t '(4 5) is a literal list, and thus a is not eq? to b, although it is equal? to b On the other hand, c is eq? to d, because '() is a constant, and both c and d are set to the same constant. Carl ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
Le 29 août 09 à 06:56, David Kastrup a écrit : Carl Sorensen writes: On Aug 28, 2009, at 1:16 PM, "Nicolas Sceaux" wrote: According to R5RS, it is an error to modify a literal list. If a function returns '(), the caller won't be allowed to apply a modifying function on the result (eg. append!) IIUC, '() is not a literal list, but a constant that represents the empty list. It is a literal list in my opinion, but one that happens to have no unique and/or modifiable conses. Append will work just fine on it. However, guile does not report modifying a literal list as an error, and actually modifies it, so this is somewhat rhetorical. It is not rhetorical since a modified literal list will actually stay modified when you call the function the next time. Can't happen with '() though. You're right on both points! thanks. ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
Carl Sorensen writes: > On Aug 28, 2009, at 1:16 PM, "Nicolas Sceaux" > wrote: > >> >> According to R5RS, it is an error to modify a literal list. >> If a function returns '(), the caller won't be allowed to >> apply a modifying function on the result (eg. append!) >> > > IIUC, '() is not a literal list, but a constant that represents the > empty list. It is a literal list in my opinion, but one that happens to have no unique and/or modifiable conses. Append will work just fine on it. >> However, guile does not report modifying a literal list as an error, >> and actually modifies it, so this is somewhat rhetorical. It is not rhetorical since a modified literal list will actually stay modified when you call the function the next time. Can't happen with '() though. guile> (define (weird) (append! '(4) '(5))) guile> (weird) (4 5) guile> (weird) (4 5 . #1#) guile> (weird) Backtrace: In standard input: 7: 0* [weird] 4: 1 [append! (4 5 . #1#) (5 . #0#)] standard input:4:17: In procedure last-pair in expression (append! (quote #) (quote #)): standard input:4:17: Circular structure in position 1: (4 5 . #1#) ABORT: (misc-error) guile> -- David Kastrup ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
On Aug 28, 2009, at 1:16 PM, "Nicolas Sceaux" wrote: > > According to R5RS, it is an error to modify a literal list. > If a function returns '(), the caller won't be allowed to > apply a modifying function on the result (eg. append!) > IIUC, '() is not a literal list, but a constant that represents the empty list. > However, guile does not report modifying a literal list as an error, > and actually modifies it, so this is somewhat rhetorical. Carl > ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
Le 27 août 09 à 22:38, Neil Puttock a écrit : 2009/8/26 Carl Sorensen : The patch looks good to me. Cheers. You code the empty list as (list). I typically code the empty list as '(). It there a preference? I suspect that we ought to be consistent, although it's not highly important. It could be part of the code janitor work, though. It's just something I noticed in a few places internally (these all seem to be changes made by Nicolas) and thought it was clearer, though admittedly I haven't been particularly consistent when deciding between the two forms. :) According to R5RS, it is an error to modify a literal list. If a function returns '(), the caller won't be allowed to apply a modifying function on the result (eg. append!) However, guile does not report modifying a literal list as an error, and actually modifies it, so this is somewhat rhetorical. nicolas ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
2009/8/26 Carl Sorensen : > The patch looks good to me. Cheers. > You code the empty list as (list). I typically code the empty list as '(). > > It there a preference? I suspect that we ought to be consistent, although > it's not highly important. It could be part of the code janitor work, > though. It's just something I noticed in a few places internally (these all seem to be changes made by Nicolas) and thought it was clearer, though admittedly I haven't been particularly consistent when deciding between the two forms. :) Regards, Neil ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
'() is preferred, as it evaluates to a constant. (list) is a function call, which might mean different things if you override the definition of list. On Wed, Aug 26, 2009 at 5:43 PM, Carl Sorensen wrote: > You code the empty list as (list). I typically code the empty list as '(). > > It there a preference? I suspect that we ought to be consistent, although > it's not highly important. It could be part of the code janitor work, > though. -- Han-Wen Nienhuys - han...@xs4all.nl - http://www.xs4all.nl/~hanwen ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
On 8/25/09 2:28 PM, "Neil Puttock" wrote: > Hi, > > I've just posted a revised patchset which deals with Han-Wen's comments. > > http://codereview.appspot.com/110047/show The patch looks good to me. I have a question about style, though. You code the empty list as (list). I typically code the empty list as '(). It there a preference? I suspect that we ought to be consistent, although it's not highly important. It could be part of the code janitor work, though. Thanks, Carl ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
Re: [PATCH] Move ambitus print callback to scheme
Hi, I've just posted a revised patchset which deals with Han-Wen's comments. http://codereview.appspot.com/110047/show Thanks, Neil ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
[PATCH] Move ambitus print callback to scheme
Hi, Please review this patch, which implements ambitus::print in output-lib.scm and removes the hard-coded ambitus length via the property 'gap. http://codereview.appspot.com/110047/show Thanks, Neil ___ lilypond-devel mailing list lilypond-devel@gnu.org http://lists.gnu.org/mailman/listinfo/lilypond-devel
