digitalmars.D.learn - cannot sort an array of char
- Ivan Kazmenko (14/14) Nov 05 2014 Hi!
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (10/24) Nov 05 2014 Hmm... this doesn't work either:
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (2/30) Nov 05 2014 https://issues.dlang.org/show_bug.cgi?id=13689
- =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/35) Nov 05 2014 It can't be a RandomAccessRange because it cannot satisfy random access
- =?UTF-8?B?QWxpIMOHZWhyZWxp?= (8/16) Nov 05 2014 Sorry, I misunderstood (again): code unit is random-access, code point
- Ivan Kazmenko (17/45) Nov 06 2014 So, you imply that to use a char array as a RandomAccessRange, I
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (6/55) Nov 06 2014 I agree. But how should it be implemented? We would have to
- Ivan Kazmenko (23/23) Nov 11 2014 IK>> For example, isRandomAccessRange[0] states the problem:
- Steven Schveighoffer (8/18) Nov 06 2014 Because sort works on ranges, and std.range has the view that char[] is
- Ivan Kazmenko (17/17) Nov 11 2014 IK>> Why is "char []" so special that it can't be sorted?
- Steven Schveighoffer (9/26) Nov 11 2014 It's safe but be careful. For instance, if c becomes an
- "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> (4/34) Nov 11 2014 That's what he meant by "bugs" :-P
Hi!
This gives an error (cannot deduce template function from
argument types):
-----
import std.algorithm;
void main () {
char [] c;
sort (c);
}
-----
Why is "char []" so special that it can't be sorted?
For example, if I know the array contains only ASCII characters,
sorting it sounds no different to sorting an "int []".
Ivan Kazmenko.
Nov 05 2014
On Wednesday, 5 November 2014 at 12:54:03 UTC, Ivan Kazmenko
wrote:
Hi!
This gives an error (cannot deduce template function from
argument types):
-----
import std.algorithm;
void main () {
char [] c;
sort (c);
}
-----
Why is "char []" so special that it can't be sorted?
For example, if I know the array contains only ASCII
characters, sorting it sounds no different to sorting an "int
[]".
Hmm... this doesn't work either:
import std.algorithm;
import std.utf;
void main () {
char [] c;
sort (c.byCodeUnit);
}
But IMO it should.
Nov 05 2014
On Wednesday, 5 November 2014 at 13:34:05 UTC, Marc Schütz wrote:On Wednesday, 5 November 2014 at 12:54:03 UTC, Ivan Kazmenko wrote:https://issues.dlang.org/show_bug.cgi?id=13689Hi! This gives an error (cannot deduce template function from argument types): ----- import std.algorithm; void main () { char [] c; sort (c); } ----- Why is "char []" so special that it can't be sorted? For example, if I know the array contains only ASCII characters, sorting it sounds no different to sorting an "int []".Hmm... this doesn't work either: import std.algorithm; import std.utf; void main () { char [] c; sort (c.byCodeUnit); } But IMO it should.
Nov 05 2014
On 11/05/2014 05:44 AM, "Marc Schütz" <schuetzm gmx.net>" wrote:On Wednesday, 5 November 2014 at 13:34:05 UTC, Marc Schütz wrote:It can't be a RandomAccessRange because it cannot satisfy random access at O(1) time. AliOn Wednesday, 5 November 2014 at 12:54:03 UTC, Ivan Kazmenko wrote:https://issues.dlang.org/show_bug.cgi?id=13689Hi! This gives an error (cannot deduce template function from argument types): ----- import std.algorithm; void main () { char [] c; sort (c); } ----- Why is "char []" so special that it can't be sorted? For example, if I know the array contains only ASCII characters, sorting it sounds no different to sorting an "int []".Hmm... this doesn't work either: import std.algorithm; import std.utf; void main () { char [] c; sort (c.byCodeUnit); } But IMO it should.
Nov 05 2014
=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> On 11/05/2014 10:01 AM, Ali Çehreli wrote:Sorry, I misunderstood (again): code unit is random-access, code point is not. Ali P.S. I would like to have a word with the Unicode people who settled on the terms "code unit" and "code point". Every time I come across one of those, I have to think at least 5 seconds to fool myself to think that I understood correctly which one was meant. :pIt can't be a RandomAccessRange because it cannot satisfy random access at O(1) time.sort (c.byCodeUnit); } But IMO it should.https://issues.dlang.org/show_bug.cgi?id=13689
Nov 05 2014
On Wednesday, 5 November 2014 at 13:34:05 UTC, Marc Schütz wrote:On Wednesday, 5 November 2014 at 12:54:03 UTC, Ivan Kazmenko wrote:So, you imply that to use a char array as a RandomAccessRange, I have to use byCodeUnit? (and it should work, but doesn't?) Fine, but how does one learn that except by asking here? Googling did not produce meaningful results for me. For example, isRandomAccessRange[0] states the problem: ----- Although char[] and wchar[] (as well as their qualified versions including string and wstring) are arrays, isRandomAccessRange yields false for them because they use variable-length encodings (UTF-8 and UTF-16 respectively). These types are bidirectional ranges only. ----- but does not offer a solution. If (when) byCodeUnit does really provide a random-access range, it would be desirable to have it linked where the problem is stated.Hi! This gives an error (cannot deduce template function from argument types): ----- import std.algorithm; void main () { char [] c; sort (c); } ----- Why is "char []" so special that it can't be sorted? For example, if I know the array contains only ASCII characters, sorting it sounds no different to sorting an "int []".Hmm... this doesn't work either: import std.algorithm; import std.utf; void main () { char [] c; sort (c.byCodeUnit); } But IMO it should.
Nov 06 2014
On Thursday, 6 November 2014 at 10:52:32 UTC, Ivan Kazmenko wrote:On Wednesday, 5 November 2014 at 13:34:05 UTC, Marc Schütz wrote:Yes. H.S. Teoh has already submitted a PR to fix it.On Wednesday, 5 November 2014 at 12:54:03 UTC, Ivan Kazmenko wrote:So, you imply that to use a char array as a RandomAccessRange, I have to use byCodeUnit? (and it should work, but doesn't?)Hi! This gives an error (cannot deduce template function from argument types): ----- import std.algorithm; void main () { char [] c; sort (c); } ----- Why is "char []" so special that it can't be sorted? For example, if I know the array contains only ASCII characters, sorting it sounds no different to sorting an "int []".Hmm... this doesn't work either: import std.algorithm; import std.utf; void main () { char [] c; sort (c.byCodeUnit); } But IMO it should.Fine, but how does one learn that except by asking here? Googling did not produce meaningful results for me. For example, isRandomAccessRange[0] states the problem: ----- Although char[] and wchar[] (as well as their qualified versions including string and wstring) are arrays, isRandomAccessRange yields false for them because they use variable-length encodings (UTF-8 and UTF-16 respectively). These types are bidirectional ranges only. ----- but does not offer a solution. If (when) byCodeUnit does really provide a random-access range, it would be desirable to have it linked where the problem is stated.I agree. But how should it be implemented? We would have to modify algorithms that require an RA range to also accept char[], but then print an error message with the suggestion to use byCodeUnit. I think that's not practicable. Any better ideas?
Nov 06 2014
IK>> For example, isRandomAccessRange[0] states the problem: IK>> ----- IK>> Although char[] and wchar[] (as well as their qualified IK>> versions including string and wstring) are arrays, IK>> isRandomAccessRange yields false for them because they use IK>> variable-length encodings (UTF-8 and UTF-16 respectively). IK>> These types are bidirectional ranges only. IK>> ----- IK>> but does not offer a solution. If (when) byCodeUnit does IK>> really provide a random-access range, it would be desirable to IK>> have it linked where the problem is stated. IK>> IK>> [0] MS> I agree. But how should it be implemented? We would have to MS> modify algorithms that require an RA range to also accept MS> char[], but then print an error message with the suggestion to MS> use byCodeUnit. I think that's not practicable. Any better MS> ideas? I meant just mentioning a workaround (byCodeUnit or representation) in the documentation, not in a compiler error. But the latter option does have some sense, too.
Nov 11 2014
On 11/5/14 7:54 AM, Ivan Kazmenko wrote:
Hi!
This gives an error (cannot deduce template function from argument types):
-----
import std.algorithm;
void main () {
char [] c;
sort (c);
}
-----
Why is "char []" so special that it can't be sorted?
Because sort works on ranges, and std.range has the view that char[] is
a range of dchar without random access. Nevermind what the compiler
thinks :)
I believe you can get what you want with std.string.representation:
import std.string;
sort(c.representation);
-Steve
Nov 06 2014
IK>> Why is "char []" so special that it can't be sorted? SS> Because sort works on ranges, and std.range has the view that SS> char[] is a range of dchar without random access. Nevermind SS> what the compiler thinks :) SS> SS> I believe you can get what you want with SS> std.string.representation: SS> SS> import std.string; SS> SS> sort(c.representation); Thank you for showing a library way to do that. I ended up with using a cast, like "sort (cast (ubyte []) c)". And this looks like a safe way to do the same. Now, std.utf's byCodeUnit and std.string's representation seem like duplicate functionality, albeit with different input and output types (and bugs :) ).
Nov 11 2014
On 11/11/14 6:07 AM, Ivan Kazmenko wrote:IK>> Why is "char []" so special that it can't be sorted? SS> Because sort works on ranges, and std.range has the view that SS> char[] is a range of dchar without random access. Nevermind SS> what the compiler thinks :) SS> SS> I believe you can get what you want with SS> std.string.representation: SS> SS> import std.string; SS> SS> sort(c.representation); Thank you for showing a library way to do that. I ended up with using a cast, like "sort (cast (ubyte []) c)". And this looks like a safe way to do the same.It's safe but be careful. For instance, if c becomes an immutable(char)[] or const(char)[], then you will have undefined behavior. If you use the representation, it will properly reject this behavior.Now, std.utf's byCodeUnit and std.string's representation seem like duplicate functionality, albeit with different input and output types (and bugs :) ).No, byCodeUnit is not an array, it's a range of char. They solve different problems, and mean different things. Note, byCodeUnit should work for sort, I'm surprised it doesn't. -Steve
Nov 11 2014
On Tuesday, 11 November 2014 at 13:20:53 UTC, Steven Schveighoffer wrote:On 11/11/14 6:07 AM, Ivan Kazmenko wrote:That's what he meant by "bugs" :-P But it's been fixed already, thanks to H.S. Teoh.IK>> Why is "char []" so special that it can't be sorted? SS> Because sort works on ranges, and std.range has the view that SS> char[] is a range of dchar without random access. Nevermind SS> what the compiler thinks :) SS> SS> I believe you can get what you want with SS> std.string.representation: SS> SS> import std.string; SS> SS> sort(c.representation); Thank you for showing a library way to do that. I ended up with using a cast, like "sort (cast (ubyte []) c)". And this looks like a safe way to do the same.It's safe but be careful. For instance, if c becomes an immutable(char)[] or const(char)[], then you will have undefined behavior. If you use the representation, it will properly reject this behavior.Now, std.utf's byCodeUnit and std.string's representation seem like duplicate functionality, albeit with different input and output types (and bugs :) ).No, byCodeUnit is not an array, it's a range of char. They solve different problems, and mean different things. Note, byCodeUnit should work for sort, I'm surprised it doesn't.
Nov 11 2014