Re: String-friendly first/rest?
clojure.contrib.string has take and drop, which do what you want (though you have to ask for exactly one character to emulate first/ rest). However, my understanding is that c.c.string is going away in 1.3, and many of its features will be removed rather than moved, so I don't think you're supposed to use it anymore. On Dec 8, 11:43 am, Surgo morgon.kan...@gmail.com wrote: To help myself learn Clojure, I figured I would write a pattern matching / destructing macro to better look like languages I'm more familiar with; i.e., destructuring by [first|second|rest] instead of [first second rest]. To do this I'm turning the aforementioned vector into a string (via str) and looking for / replacing the | character. However, this led to the following issue... (def test abc) (first test) \a (rest test) (\b \c) (string? (rest test)) false It would be really helpful if first/rest returned strings (or a character in the case of first), not lists, when given string input. Is there a design reason for the current behaviour and, if so, are there equivalent built-in functions that do the right thing for strings? -- 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
Re: String-friendly first/rest?
On Dec 9, 12:52 pm, Alan a...@malloys.org wrote: rest). However, my understanding is that c.c.string is going away in 1.3, and many of its features will be removed rather than moved, so I Yes, it is replaced by clojure.string. c.c.string is deprecated in 1.2 and removed in 1.3 -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
Re: String-friendly first/rest?
2010/12/8 Surgo morgon.kan...@gmail.com To help myself learn Clojure, I figured I would write a pattern matching / destructing macro to better look like languages I'm more familiar with; i.e., destructuring by [first|second|rest] instead of [first second rest]. To do this I'm turning the aforementioned vector into a string (via str) and looking for / replacing the | character. However, this led to the following issue... (def test abc) (first test) \a (rest test) (\b \c) (string? (rest test)) false It would be really helpful if first/rest returned strings (or a character in the case of first), not lists, when given string input. Is there a design reason for the current behaviour and, if so, are there equivalent built-in functions that do the right thing for strings? (first abc) gives you a character. (rest anything) returns a seq, by definition. It's not about Strings, it's the contract of rest. A String is not a seq, but it's viewable as a seq, in which case each element of the seq will be a character of the String. Note that this is not particular to String, but to almost any clojure datastructure : (rest [1 2 3]) doesn't return a vector either, but a seq: (2 3) etc. You seem to want to not use seq abstractions, but String manipulation abstractions, here. -- 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.comclojure%2bunsubscr...@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 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
Re: String-friendly first/rest?
(rest anything) returns a seq, by definition. It's not about Strings, it's the contract of rest. A String is not a seq, but it's viewable as a seq, in which case each element of the seq will be a character of the String. Note that this is not particular to String, but to almost any clojure datastructure : (rest [1 2 3]) doesn't return a vector either, but a seq: (2 3) etc. You seem to want to not use seq abstractions, but String manipulation abstractions, here. That's a fair criticism. I suppose that I'm not necessarily looking for specifically String manipulation abstractions (I can just do a (.substr abc 1) to get bc as a String after all), but rather looking for an abstraction that takes something that's addressable as a sequence and returns it in the same format or type instead of a seq. -- 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
Re: String-friendly first/rest?
Laurent is right. Best to use substring: (.substring test 1 (count test)) bc On Dec 8, 12:43 pm, Surgo morgon.kan...@gmail.com wrote: To help myself learn Clojure, I figured I would write a pattern matching / destructing macro to better look like languages I'm more familiar with; i.e., destructuring by [first|second|rest] instead of [first second rest]. To do this I'm turning the aforementioned vector into a string (via str) and looking for / replacing the | character. However, this led to the following issue... (def test abc) (first test) \a (rest test) (\b \c) (string? (rest test)) false It would be really helpful if first/rest returned strings (or a character in the case of first), not lists, when given string input. Is there a design reason for the current behaviour and, if so, are there equivalent built-in functions that do the right thing for strings? -- 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
Re: String-friendly first/rest?
Hi, Am 08.12.2010 um 23:05 schrieb Surgo: That's a fair criticism. I suppose that I'm not necessarily looking for specifically String manipulation abstractions (I can just do a (.substr abc 1) to get bc as a String after all), but rather looking for an abstraction that takes something that's addressable as a sequence and returns it in the same format or type instead of a seq. Namespaces to the rescue: (ns your.name.space (:refer-clojure :exclude (first rest))) (defprotocol MySeq (first [this]) (rest [this])) (extend-protocol MySeq String (first [this] (.charAt this 0)) (rest [this] (subs this 1)) Object (first [this] (clojure.core/first this)) (rest [this] (clojure.core/rest this))) Now use first and rest as normal. Here some examples: your.name.space= (first abc) \a your.name.space= (rest abc) bc your.name.space= (first [1 2 3]) 1 your.name.space= (rest [1 2 3]) (2 3) Sincerely Meikel -- 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
Re: String-friendly first/rest?
(subs test 1) will work as well; the default behavior is to go to the end if no end position is specified. On Dec 8, 3:16 pm, Miki miki.teb...@gmail.com wrote: (.substring test 1 (count test)) bc FYI: Clojure has subs - (subs test 1 (count test)) -- 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
Re: String-friendly first/rest?
2010/12/8 Surgo morgon.kan...@gmail.com (rest anything) returns a seq, by definition. It's not about Strings, it's the contract of rest. A String is not a seq, but it's viewable as a seq, in which case each element of the seq will be a character of the String. Note that this is not particular to String, but to almost any clojure datastructure : (rest [1 2 3]) doesn't return a vector either, but a seq: (2 3) etc. You seem to want to not use seq abstractions, but String manipulation abstractions, here. That's a fair criticism. I suppose that I'm not necessarily looking for specifically String manipulation abstractions (I can just do a (.substr abc 1) to get bc as a String after all), but rather looking for an abstraction that takes something that's addressable as a sequence and returns it in the same format or type instead of a seq. No such builtin that I'm aware of. There are some functor things in clojure contrib, but I don't know them well. -- 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
Re: String-friendly first/rest?
On Dec 8, 2010, at 4:05 PM, Surgo wrote:
That's a fair criticism. I suppose that I'm not necessarily looking
for specifically String manipulation abstractions (I can just do a
(.substr abc 1) to get bc as a String after all), but rather
looking for an abstraction that takes something that's addressable as
a sequence and returns it in the same format or type instead of a seq.
So something like an inverse to (seq)? You could write such a thing, though it
would have to know about each type (seq) knows about. More importantly, it
would have to somehow know what type the thing originally was, since there's no
difference between e.g. (seq abc) and (seq [\a \b \c]). You'd either have to
store the type when calling (seq) and manually pass it when calling the inverse
function, or else I suppose you could write a wrapper for (seq) that adds
metadata about what type the thing originally was.
Incidentally, while testing this last idea, I was surprised to find that :type
metadata is treated specially:
= (with-meta '() {:type (type [])})
[]
I assume this means :type is used internally by Clojure somehow. I notice
clojure.org says that metadata is used to convey information to the compiler
about types, but ought there be a list of reserved metadata?
--
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
Re: String-friendly first/rest?
2010/12/8 Michael Gardner gardne...@gmail.com
On Dec 8, 2010, at 4:05 PM, Surgo wrote:
That's a fair criticism. I suppose that I'm not necessarily looking
for specifically String manipulation abstractions (I can just do a
(.substr abc 1) to get bc as a String after all), but rather
looking for an abstraction that takes something that's addressable as
a sequence and returns it in the same format or type instead of a seq.
So something like an inverse to (seq)? You could write such a thing, though
it would have to know about each type (seq) knows about. More importantly,
it would have to somehow know what type the thing originally was, since
there's no difference between e.g. (seq abc) and (seq [\a \b \c]). You'd
either have to store the type when calling (seq) and manually pass it when
calling the inverse function, or else I suppose you could write a wrapper
for (seq) that adds metadata about what type the thing originally was.
Well, to the contrary, I think it would be a different abstraction from seq.
seq abstraction is for providing a view over things which are seqable, but
not necessarily data structures: can be streams, etc. And some
datastructures know how to present a seq view of them without placing an
importance on the sequential aspect of this (the ordering of the elements of
the seq).
So this new abstraction would concern less input than seq. Only the input
for which ordering is an information (Strings, vectors, etc.).
Meikel showed the way, though it's different enough in semantics to deserve
its own protocol and not override (in fact replace, in his example) existing
concepts.
Now I don't (really, I don't) know if there's interest in providing this, at
this level of genericity.
Incidentally, while testing this last idea, I was surprised to find that
:type metadata is treated specially:
= (with-meta '() {:type (type [])})
[]
I assume this means :type is used internally by Clojure somehow. I notice
clojure.org says that metadata is used to convey information to the
compiler about types, but ought there be a list of reserved metadata?
--
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.comclojure%2bunsubscr...@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 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
Re: String-friendly first/rest?
Hi, Am 08.12.2010 um 23:53 schrieb Laurent PETIT: Meikel showed the way, though it's different enough in semantics to deserve its own protocol and not override (in fact replace, in his example) existing concepts. Well, this showed up the second time in two days, so I thought I'd write it up in an email. However: I strongly discourage doing such things. I would scratch a project working internally like that from my dependency list. (luckily the effects of such a protocol are limited to opt-in namespaces) Listen to Laurent! He is an experienced clojurian. This is a different thing. Name it differently! Handle it differently! As the way Clojure works: Listen to Rich! He has probably thought more about this, than anyone else ever will. If something is not the way you expect it to be or something is missing, then there is almost surely a reason for this fact. If you still think, that something should be changed, lobby for the change on the mailing list. Sincerely Meikel -- 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
Re: String-friendly first/rest?
On Wed, Dec 8, 2010 at 2:00 PM, Laurent PETIT laurent.pe...@gmail.com wrote: (def test abc) (first test) \a (rest test) (\b \c) (string? (rest test)) false It would be really helpful if first/rest returned strings (or a character in the case of first), not lists, when given string input. Is there a design reason for the current behaviour and, if so, are there equivalent built-in functions that do the right thing for strings? (first abc) gives you a character. (rest anything) returns a seq, by definition. It's not about Strings, it's the contract of rest. A String is not a seq, but it's viewable as a seq, in which case each element of the seq will be a character of the String. This behaviour would be a lot easier to deal with if into worked with strings. -Phil -- 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
