* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern [not found] ` <E1YrVuR-00064X-CK@vcs.savannah.gnu.org> @ 2015-05-11 4:15 ` Stefan Monnier 2015-05-11 13:42 ` Nicolas Petton 0 siblings, 1 reply; 7+ messages in thread From: Stefan Monnier @ 2015-05-11 4:15 UTC (permalink / raw To: emacs-devel; +Cc: Nicolas Petton > + (pcase-defmacro seq (bindings) > + `(and ,@(seq--make-pcase-bindings bindings))) If you put a docstring in there, it will appear in "C-h f pcase RET", so you can use it to document the particular format you support. Also I see the following problems: - You only accept the form (seq <binding>) rather than (seq <binding1> <binding2> ...), so typical cases will have to use (seq (a b)) instead (seq a b). - The above pcase pattern doesn't check that it's indeed a `seq'. You should add a (pred seq-p). It will automatically be optimized away in `pcase-let', but is indispensable for the `pcase' situation to do the right thing. > +(defun seq--make-pcase-bindings (args &optional bindings nested-indexes) [...] > + (seq-doseq (name args) > + (unless rest-marker > + (pcase name > + ((pred seq-p) IIUC, this means that (pcase-let (((seq a (seq b c)) <obj>)) <body>) will bind the `seq' variable to the first element of the nested sequence (and `a' to the second and `b' to the third), whereas I think it should bind `b' to the first element of the nested sequence (which is what would happen if you simply removed this branch of this `pcase'). I think removing this case will also remove the need for seq--nested-elt. > + (push `(app (seq--reverse-args #'seq--nested-elt > + (reverse (cons ,index ',nested-indexes))) > + ,name) This reverse plus seq--reverse-args business seems hideously inefficient. Why do you need that? Stefan ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-11 4:15 ` [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern Stefan Monnier @ 2015-05-11 13:42 ` Nicolas Petton 2015-05-11 15:06 ` Stefan Monnier 0 siblings, 1 reply; 7+ messages in thread From: Nicolas Petton @ 2015-05-11 13:42 UTC (permalink / raw To: Stefan Monnier; +Cc: Nicolas Petton, emacs-devel [-- Attachment #1: Type: text/plain, Size: 2130 bytes --] Stefan Monnier writes: >> + (pcase-defmacro seq (bindings) >> + `(and ,@(seq--make-pcase-bindings bindings))) > > If you put a docstring in there, it will appear in "C-h f pcase RET", so > you can use it to document the particular format you support. Great, I'll do that. > Also I see the following problems: > - You only accept the form (seq <binding>) rather than (seq <binding1> > <binding2> ...), so typical cases will have to use (seq (a b)) instead > (seq a b). Yes. My idea of it was that you bind a sequence like the following: (seq [a b [c d]]) Or did you have something else in mind? > - The above pcase pattern doesn't check that it's indeed a `seq'. > You should add a (pred seq-p). It will automatically be optimized > away in `pcase-let', but is indispensable for the `pcase' situation to > do the right thing. Ok, I'll do that. > >> +(defun seq--make-pcase-bindings (args &optional bindings nested-indexes) > [...] >> + (seq-doseq (name args) >> + (unless rest-marker >> + (pcase name >> + ((pred seq-p) > > IIUC, this means that (pcase-let (((seq a (seq b c)) <obj>)) <body>) > will bind the `seq' variable to the first element of the nested sequence > (and `a' to the second and `b' to the third), whereas I think it should > bind `b' to the first element of the nested sequence (which is what > would happen if you simply removed this branch of this `pcase'). > I think removing this case will also remove the need for > seq--nested-elt. But then how can I have `seq-let' work the way it did until now? For instance: (seq-let [a [b [c]]] my-vector ...) >> + (push `(app (seq--reverse-args #'seq--nested-elt >> + (reverse (cons ,index ',nested-indexes))) >> + ,name) > > This reverse plus seq--reverse-args business seems > hideously inefficient. Why do you need that? because of the way the `app' pattern works. Or maybe I'm missing something? Nico -- Nicolas Petton http://nicolas-petton.fr [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 512 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-11 13:42 ` Nicolas Petton @ 2015-05-11 15:06 ` Stefan Monnier 2015-05-11 21:13 ` Nicolas Petton 2015-05-11 21:35 ` Nicolas Petton 0 siblings, 2 replies; 7+ messages in thread From: Stefan Monnier @ 2015-05-11 15:06 UTC (permalink / raw To: Nicolas Petton; +Cc: emacs-devel > Yes. My idea of it was that you bind a sequence like the following: > (seq [a b [c d]]) I was thinking of (seq a b (seq c d)). You could add support for (seq a b [c d]), if you want since that currently wouldn't collide with any pcase pattern, tho I'm not sure it's worth the added complexity for the user. > But then how can I have `seq-let' work the way it did until now? For > instance: > (seq-let [a [b [c]]] my-vector > ...) You expand [a [b [c]]] to (seq a (seq b (seq c))) before passing it to pcase-let. >>> + (push `(app (seq--reverse-args #'seq--nested-elt >>> + (reverse (cons ,index ',nested-indexes))) >>> + ,name) >> This reverse plus seq--reverse-args business seems >> hideously inefficient. Why do you need that? > because of the way the `app' pattern works. Or maybe I'm missing > something? Why wouldn't `(app (seq--nested-elt ',(reverse (cons index nested-indexes))) ,name) work as well? Or, once you get rid of the nested case, `(app (seq-elt ,index) ,name) -- Stefan ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-11 15:06 ` Stefan Monnier @ 2015-05-11 21:13 ` Nicolas Petton 2015-05-11 21:35 ` Nicolas Petton 1 sibling, 0 replies; 7+ messages in thread From: Nicolas Petton @ 2015-05-11 21:13 UTC (permalink / raw To: Stefan Monnier; +Cc: Nicolas Petton, emacs-devel [-- Attachment #1: Type: text/plain, Size: 1415 bytes --] Stefan Monnier writes: >> Yes. My idea of it was that you bind a sequence like the following: >> (seq [a b [c d]]) > > I was thinking of (seq a b (seq c d)). > > You could add support for (seq a b [c d]), if you want since that > currently wouldn't collide with any pcase pattern, tho I'm not sure it's > worth the added complexity for the user. > >> But then how can I have `seq-let' work the way it did until now? For >> instance: >> (seq-let [a [b [c]]] my-vector >> ...) > > You expand [a [b [c]]] to (seq a (seq b (seq c))) before passing it to > pcase-let. > >>>> + (push `(app (seq--reverse-args #'seq--nested-elt >>>> + (reverse (cons ,index ',nested-indexes))) >>>> + ,name) >>> This reverse plus seq--reverse-args business seems >>> hideously inefficient. Why do you need that? >> because of the way the `app' pattern works. Or maybe I'm missing >> something? > > Why wouldn't > > `(app (seq--nested-elt ',(reverse (cons index nested-indexes))) ,name) > > work as well? Or, once you get rid of the nested case, > > `(app (seq-elt ,index) ,name) I understand what you meant now. It indeed makes sense, and the pcase pattern would be much more consistent. I'll push another commit. Cheers, Nico > > > -- Stefan -- Nicolas Petton http://nicolas-petton.fr [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 512 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-11 15:06 ` Stefan Monnier 2015-05-11 21:13 ` Nicolas Petton @ 2015-05-11 21:35 ` Nicolas Petton 2015-05-12 1:03 ` Stefan Monnier 1 sibling, 1 reply; 7+ messages in thread From: Nicolas Petton @ 2015-05-11 21:35 UTC (permalink / raw To: Stefan Monnier; +Cc: Petton, emacs-devel [-- Attachment #1: Type: text/plain, Size: 435 bytes --] Stefan Monnier writes: > Why wouldn't > > `(app (seq--nested-elt ',(reverse (cons index nested-indexes))) ,name) > > work as well? Or, once you get rid of the nested case, > > `(app (seq-elt ,index) ,name) Wouldn't that result in passing the sequence as the second argument of `seq-elt'? That was the reason why I added this reversed arguments. Cheers, Nico -- Nicolas Petton http://nicolas-petton.fr [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 512 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-11 21:35 ` Nicolas Petton @ 2015-05-12 1:03 ` Stefan Monnier 2015-05-12 6:51 ` Nicolas Petton 0 siblings, 1 reply; 7+ messages in thread From: Stefan Monnier @ 2015-05-12 1:03 UTC (permalink / raw To: Nicolas Petton; +Cc: emacs-devel > Wouldn't that result in passing the sequence as the second argument of > `seq-elt'? Yes. Sorry, I missed that `elt' takes args in the same order as `aref' rather than `nth'. > That was the reason why I added this reversed arguments. Ah, in this case, I guess you could use pcase--flip (or equivalent). Notice that it's a macro, so the arg-reversal will take place at compile-time. Stefan ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern 2015-05-12 1:03 ` Stefan Monnier @ 2015-05-12 6:51 ` Nicolas Petton 0 siblings, 0 replies; 7+ messages in thread From: Nicolas Petton @ 2015-05-12 6:51 UTC (permalink / raw To: Stefan Monnier; +Cc: Nicolas Petton, emacs-devel [-- Attachment #1: Type: text/plain, Size: 553 bytes --] Stefan Monnier writes: >> Wouldn't that result in passing the sequence as the second argument of >> `seq-elt'? > > Yes. Sorry, I missed that `elt' takes args in the same order as `aref' > rather than `nth'. > >> That was the reason why I added this reversed arguments. > > Ah, in this case, I guess you could use pcase--flip (or equivalent). > Notice that it's a macro, so the arg-reversal will take place at > compile-time. Thanks for the tip, I didn't know about pcase--flip. Nico -- Nicolas Petton http://nicolas-petton.fr [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 512 bytes --] ^ permalink raw reply [flat|nested] 7+ messages in thread
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[not found] ` <E1YrVuR-00064X-CK@vcs.savannah.gnu.org>
2015-05-11 4:15 ` [Emacs-diffs] master 387e1e1: New version of `seq-let' based on a pcase pattern Stefan Monnier
2015-05-11 13:42 ` Nicolas Petton
2015-05-11 15:06 ` Stefan Monnier
2015-05-11 21:13 ` Nicolas Petton
2015-05-11 21:35 ` Nicolas Petton
2015-05-12 1:03 ` Stefan Monnier
2015-05-12 6:51 ` Nicolas Petton
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