Re: Adding implicit indexing to Clojure lists and arrays?
(defn indexed Returns a lazy sequence of [index, item] pairs, where items come from 's' and indexes count up from zero. (indexed '(a b c d)) = ([0 a] [1 b] [2 c] [3 d]) [s] (map vector (iterate inc 0) s)) -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Adding implicit indexing to Clojure lists and arrays?
Mike or mikera is fine :-) If you wanted to provide this kind of functionality, I'd normally suggest doing it with a protocol. Something like: (defprotocol PWrappedIndex (get-wrapped [coll index])) (extend-protocol PWrappedIndex clojure.lang.Indexed (get-wrapped [coll index] (nth coll (mod index (count coll) (get-wrapped [0 1 2 3 4 5 6 7 8 9] -2) = 8 This is incidentally the same technique that core.matrix uses to extend a common matrix API to arbitrary matrix types. On Thursday, 27 June 2013 23:00:48 UTC+1, Greg Slepak wrote: Thanks Mike (or do you go by Mikera as your email alias suggests?), I think you make very good points, so I withdraw my request. I'm curious though... Just as a learning experience, would it be possible to tack on such syntax implicit indexing and slicing using Clojure's extend-type function? Thanks, Greg On Jun 27, 2013, at 6:45 AM, Mikera mike.r.an...@gmail.com javascript: wrote: I agree that negative indexing (and presumably also modulo indexing for the upper index?) is very useful. Stuff like this comes up all the time in core.matrix However I don't think it makes sense as a standard feature in Clojure's low-level data constructs for several reasons: a) It's a breaking change for people who are handling out-of-bounds cases b) In new code it will mask out-of-bounds errors, which can conceal some nasty bugs c) Cramming more implicit features into existing constructs is a bad idea in general: explicit is better d) It probably adds a small performance overhead. Not worth making everyone pay a cost for one special case feature This kind of thing is IMHO better handled by either wrapping the vector in a function, or creating some kind of extra collection wrapper that provides the negative indexing functionality. On Thursday, 27 June 2013 04:19:24 UTC+1, Michael-Keith Bernard (SegFaultAX) wrote: Vectors and maps are already functions of their indices and keys, respectively. I don't really think it makes sense for other sequence types (seqs, lists, etc.) because they aren't naturally associative in the same way. Finally, there isn't a Clojure form I'm aware of that allows negative indices in the same way eg Python does, but I for one would find that incredibly useful. On Wednesday, June 26, 2013 8:01:02 PM UTC-7, Greg Slepak wrote: There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clo...@googlegroups.com javascript: Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+u...@googlegroups.com javascript: For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+u...@googlegroups.com javascript:. For more options, visit https://groups.google.com/groups/opt_out. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Adding implicit indexing to Clojure lists and arrays?
I agree that negative indexing (and presumably also modulo indexing for the upper index?) is very useful. Stuff like this comes up all the time in core.matrix However I don't think it makes sense as a standard feature in Clojure's low-level data constructs for several reasons: a) It's a breaking change for people who are handling out-of-bounds cases b) In new code it will mask out-of-bounds errors, which can conceal some nasty bugs c) Cramming more implicit features into existing constructs is a bad idea in general: explicit is better d) It probably adds a small performance overhead. Not worth making everyone pay a cost for one special case feature This kind of thing is IMHO better handled by either wrapping the vector in a function, or creating some kind of extra collection wrapper that provides the negative indexing functionality. On Thursday, 27 June 2013 04:19:24 UTC+1, Michael-Keith Bernard (SegFaultAX) wrote: Vectors and maps are already functions of their indices and keys, respectively. I don't really think it makes sense for other sequence types (seqs, lists, etc.) because they aren't naturally associative in the same way. Finally, there isn't a Clojure form I'm aware of that allows negative indices in the same way eg Python does, but I for one would find that incredibly useful. On Wednesday, June 26, 2013 8:01:02 PM UTC-7, Greg Slepak wrote: There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Adding implicit indexing to Clojure lists and arrays?
Thanks Mike (or do you go by Mikera as your email alias suggests?), I think you make very good points, so I withdraw my request. I'm curious though... Just as a learning experience, would it be possible to tack on such syntax implicit indexing and slicing using Clojure's extend-type function? Thanks, Greg On Jun 27, 2013, at 6:45 AM, Mikera mike.r.anderson...@gmail.com wrote: I agree that negative indexing (and presumably also modulo indexing for the upper index?) is very useful. Stuff like this comes up all the time in core.matrix However I don't think it makes sense as a standard feature in Clojure's low-level data constructs for several reasons: a) It's a breaking change for people who are handling out-of-bounds cases b) In new code it will mask out-of-bounds errors, which can conceal some nasty bugs c) Cramming more implicit features into existing constructs is a bad idea in general: explicit is better d) It probably adds a small performance overhead. Not worth making everyone pay a cost for one special case feature This kind of thing is IMHO better handled by either wrapping the vector in a function, or creating some kind of extra collection wrapper that provides the negative indexing functionality. On Thursday, 27 June 2013 04:19:24 UTC+1, Michael-Keith Bernard (SegFaultAX) wrote: Vectors and maps are already functions of their indices and keys, respectively. I don't really think it makes sense for other sequence types (seqs, lists, etc.) because they aren't naturally associative in the same way. Finally, there isn't a Clojure form I'm aware of that allows negative indices in the same way eg Python does, but I for one would find that incredibly useful. On Wednesday, June 26, 2013 8:01:02 PM UTC-7, Greg Slepak wrote: There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Adding implicit indexing to Clojure lists and arrays?
There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Adding implicit indexing to Clojure lists and arrays?
Vectors and maps are already functions of their indices and keys, respectively. I don't really think it makes sense for other sequence types (seqs, lists, etc.) because they aren't naturally associative in the same way. Finally, there isn't a Clojure form I'm aware of that allows negative indices in the same way eg Python does, but I for one would find that incredibly useful. On Wednesday, June 26, 2013 8:01:02 PM UTC-7, Greg Slepak wrote: There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Adding implicit indexing to Clojure lists and arrays?
(v 0) and the like already work when v is a vector. You can also do something like this: (defn proper-rem [a b] (if (neg? a) (dec (- b (rem (- (inc a)) b))) (rem a b))) (defn at [v idx] (v (proper-rem idx (count v (defn r [start end v] (let [c (count v) s (proper-rem start c) e (proper-rem end c) s2 (min s e) e2 (max s e) (subvec v s2 e2))) (at '[a b c d e f g] -1) g (r '[a b c d e f g] -2 2) [c d e] On Wed, Jun 26, 2013 at 11:01 PM, Greg g...@kinostudios.com wrote: There is one feature that I really miss from newLISP and seems like it could be a natural extension to Clojure, and that is implicit indexing for lists and arrays. Clojure already has something similar in its use of keywords to act as functions that look themselves up in a map. This is basically the same concept, but using numbers instead. Implicit indexing creates a really elegant syntax for finding elements and ranges in a list or array. Here's an example: (setf mylist '(a b c d e f g)) (a b c d e f g) (mylist 0) a (mylist -1) g (0 3 mylist) (a b c) Has this been considered already? Would this be something that could be added to the language syntax? Thanks for your consideration! Sincerely, Greg -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
