Re: byLine(n)?
On Sunday, 11 June 2017 at 05:36:08 UTC, helxi wrote:
I was writing a program that reads and prints the first nth
lines to the stdout:
import std.stdio;
void main(string[] args)
{
import std.algorithm, std.range;
import std.conv;
stdin.byLine.take(args[1].to!ulong).each!writeln;
}
As far as I understand the stdin.byLine.take(args[1].to!ulong)
part reads all the lines written in stdin.
What if I want to make byLine read only and only first nth line?
stdin.byLine(args[1].to!ulong).each!writeln;
Obviously the code above won't work. Is there any efficient
workaround?
You need only the nth line? Then you'd need to `drop` the
preceding ones:
void main(string[] args) {
import std.algorithm, std.range, std.stdio, std.conv;
stdin.byLine.drop(args[1].to!int-1).front.writeln;
}
Or if you need every nth line, combine `drop` and `stride`:
void main(string[] args) {
import std.algorithm, std.range, std.stdio, std.conv;
auto step = args[1].to!int;
stdin.byLine.drop(step-1).stride(step).each!writeln;
}
byLine(n)?
I was writing a program that reads and prints the first nth lines
to the stdout:
import std.stdio;
void main(string[] args)
{
import std.algorithm, std.range;
import std.conv;
stdin.byLine.take(args[1].to!ulong).each!writeln;
}
As far as I understand the stdin.byLine.take(args[1].to!ulong)
part reads all the lines written in stdin.
What if I want to make byLine read only and only first nth line?
stdin.byLine(args[1].to!ulong).each!writeln;
Obviously the code above won't work. Is there any efficient
workaround?
Re: brew install dmd
On Sunday, 11 June 2017 at 03:48:57 UTC, Joel wrote: On Sunday, 11 June 2017 at 02:38:21 UTC, Mike Parker wrote: On Sunday, 11 June 2017 at 01:30:37 UTC, Joel wrote: but still 2.074.0 (not 74.1) Joels-MacBook-Pro:Testing joelchristensen$ dmd DMD64 D Compiler v2.074.0 It's probably related to this: http://forum.dlang.org/post/abyacihlxtcphnhzi...@forum.dlang.org Looks like I could put this: curl https://i.dlang.io | bash -s But I'm not sure about doing this. This is a copy of the __official__ D installer as advertised on dlang.org (http://dlang.org/download.html): curl -fsS https://dlang.org/install.sh | bash -s dmd (the releases are signed) i.dlang.io is just a handy alternative, s.t. you can save keystrokes on a foreign machine and install dmd in 25 keystrokes (`curl i.dlang.io | bash -s`).
Re: brew install dmd
On Sunday, 11 June 2017 at 03:54:05 UTC, Mike Parker wrote: On Sunday, 11 June 2017 at 03:48:57 UTC, Joel wrote: curl https://i.dlang.io | bash -s But I'm not sure about doing this. I'm don't what that means, but Homebrew is giving you 2.074.1, it's just that the binary has the wrong version number compiled in. Oh, ok. Thanks Mike.
Re: brew install dmd
On Sunday, 11 June 2017 at 03:48:57 UTC, Joel wrote: curl https://i.dlang.io | bash -s But I'm not sure about doing this. I'm don't what that means, but Homebrew is giving you 2.074.1, it's just that the binary has the wrong version number compiled in.
Re: brew install dmd
On Sunday, 11 June 2017 at 02:38:21 UTC, Mike Parker wrote: On Sunday, 11 June 2017 at 01:30:37 UTC, Joel wrote: but still 2.074.0 (not 74.1) Joels-MacBook-Pro:Testing joelchristensen$ dmd DMD64 D Compiler v2.074.0 It's probably related to this: http://forum.dlang.org/post/abyacihlxtcphnhzi...@forum.dlang.org Looks like I could put this: curl https://i.dlang.io | bash -s But I'm not sure about doing this.
Re: brew install dmd
On Sunday, 11 June 2017 at 01:30:37 UTC, Joel wrote: but still 2.074.0 (not 74.1) Joels-MacBook-Pro:Testing joelchristensen$ dmd DMD64 D Compiler v2.074.0 It's probably related to this: http://forum.dlang.org/post/abyacihlxtcphnhzi...@forum.dlang.org
brew install dmd
but still 2.074.0 (not 74.1) I'm not that familier brew. I've tried `brew upgrade` and `brew update`. Joels-MacBook-Pro:Testing joelchristensen$ brew upgrade dmd ==> Upgrading 1 outdated package, with result: dmd 2.074.1 ==> Upgrading dmd ==> Downloading https://homebrew.bintray.com/bottles/dmd-2.074.1.sierra.bottle.t 100.0% ==> Pouring dmd-2.074.1.sierra.bottle.tar.gz ==> Using the sandbox Warning: An old dmd.conf was found and will be moved to /usr/local/etc/dmd.conf.old. 🍺 /usr/local/Cellar/dmd/2.074.1: 587 files, 67MB Joels-MacBook-Pro:Testing joelchristensen$ dmd DMD64 D Compiler v2.074.0
Re: Dub or Dmd trying to use some funny path to find linker.exe
On 06/10/2017 07:04 PM, WhatMeWorry wrote: Dub or Dmd dies when it can't find the linker. Like so: C:\Users\kheaser\Git\Delivery\projects\00_01_print_ogl_ver>dub run --arch=x86_64 --force Performing "debug" build using dmd for x86_64. derelict-util 2.0.6: building configuration "library"... derelict-al 1.0.3: building configuration "library"... derelict-assimp3 1.3.0: building configuration "library"... derelict-fi 2.0.3: building configuration "library"... derelict-fmod 2.0.4: building configuration "library"... derelict-ft 1.1.3: building configuration "library"... derelict-gl3 1.0.23: building configuration "library"... derelict-glfw3 3.1.3: building configuration "derelict-glfw3-dynamic"... 00_01_print_ogl_ver ~master: building configuration "application"... Linking... Error: can't run 'C:\Users\Administrator\Desktop\VC\\bin\x86_amd64\link.exe', check PATH dmd failed with exit code -1. C:\Users\kheaser\OneDrive for Business\GitHub\Delivery\projects\00_01_print_ogl_ver>where link.exe C:\D\dmd2\windows\bin\link.exe First off, I have no idea why dub (or dmd) is trying to use the path C:\Users\Administrator\Desktop\VC\\bin\x86_amd64\ to find link.exe? I did the where command link.exe to show that the linker is in my PATH at C:\D\dmd2\windows\bin\. So can I specify the linker path explicitly and if so, how is that done? Sorry if this is a stupid question, but I've looked at the documentation all morning and not finding anything. Thanks. You are building a 64bit executable, and in that case the linker shiped with dmd isn't used, as it only handles 32bit (OMF). dmd instead relies on the microsoft linker. Judging from the error the path to the Windows SDK / linker is not set correctly in dmd's sc.ini. -- Mike Wey
Re: when I run dub within git bash, dub prompts are not displayed. For instance...
On Saturday, 10 June 2017 at 16:11:31 UTC, WhatMeWorry wrote:
kheaser@IT-ASST-SB MINGW64
/c/Users/kheaser/Git/Delivery/projects (master)
$ dub init 00_01_print_ogl_ver
... All this white space here is me just pressing the Enter key
... to get the default values.
If the problem is that the text doesn't show until you've entered
past all the prompts and the program exits, then it's the
terminal you're using not playing well with D.
With the default Cygwin terminal this will not show a delayed
countdown, but rather all numbers at once after the combined
pause:
import std.stdio;
import core.thread;
void main()
{
foreach (i; 0..5)
{
writeln(i);
Thread.sleep(1.seconds);
}
}
With the normal Windows command prompt, it behaves as it should.
Someone else will have to explain what the problem is, but it's
something about the terminal not acting like a proper tty or
something along those lines.
Re: std.stdio.stderr
On Sat, 2017-06-10 at 16:45 +, Antonio Corbi via Digitalmars-d- learn wrote: > […] > > It seems to work for me with a dumb example: […] Spurred on by your report of success, I discovered my error. D treats a char[1024] as 1024 characters when using the %s format specifier. I had to use fromStringz using a cast to get the %s to get the null terminated string. The problems of idiomatic C code (crap) converted to D code (good, but with hacks). Thanks for your reply, it was most helpful. -- Russel. = Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder signature.asc Description: This is a digitally signed message part
Dub or Dmd trying to use some funny path to find linker.exe
Dub or Dmd dies when it can't find the linker. Like so: C:\Users\kheaser\Git\Delivery\projects\00_01_print_ogl_ver>dub run --arch=x86_64 --force Performing "debug" build using dmd for x86_64. derelict-util 2.0.6: building configuration "library"... derelict-al 1.0.3: building configuration "library"... derelict-assimp3 1.3.0: building configuration "library"... derelict-fi 2.0.3: building configuration "library"... derelict-fmod 2.0.4: building configuration "library"... derelict-ft 1.1.3: building configuration "library"... derelict-gl3 1.0.23: building configuration "library"... derelict-glfw3 3.1.3: building configuration "derelict-glfw3-dynamic"... 00_01_print_ogl_ver ~master: building configuration "application"... Linking... Error: can't run 'C:\Users\Administrator\Desktop\VC\\bin\x86_amd64\link.exe', check PATH dmd failed with exit code -1. C:\Users\kheaser\OneDrive for Business\GitHub\Delivery\projects\00_01_print_ogl_ver>where link.exe C:\D\dmd2\windows\bin\link.exe First off, I have no idea why dub (or dmd) is trying to use the path C:\Users\Administrator\Desktop\VC\\bin\x86_amd64\ to find link.exe? I did the where command link.exe to show that the linker is in my PATH at C:\D\dmd2\windows\bin\. So can I specify the linker path explicitly and if so, how is that done? Sorry if this is a stupid question, but I've looked at the documentation all morning and not finding anything. Thanks.
Re: std.stdio.stderr
On Saturday, 10 June 2017 at 16:10:18 UTC, Russel Winder wrote:
It appears that std.stdio.stderr does not wor exactly as stdio
stderr
does. In particular std.stdio.stderr.writef(…) does not work as
fprintf(stderr…) does.
Some code I am porting from C++ to D makes use of ANSI escape
codes to go up a line and overwrite what was there, as well as
change colours. This work fine in the C++ code but fails in the
D code. The codes are definitely all the same, the only
difference is in the writing functions.
Is this problem to be expected or should it work?
Hi Russel,
It seems to work for me with a dumb example:
```
import std.stdio;
void main()
{
writefln("stdout: %s", "[7m[1mEdit source/app.d to start your
project.[0m");
stderr.writefln("stderr: %s", "[7m[1mEdit source/app.d to
start your project.[0m");
stderr.writefln("stderr: %s", "[0;31m[1mEdit source/app.d to
start your project.[0m");
stderr.writefln("%s", "[1A[12C[K");
}
```
Before copy/paste take into account that in sequences like "[7m",
etc... there's a hidden ESC char at the beginning, something
like: "\033[7m", and I can't see it in the preview of my posting.
Antonio
when I run dub within git bash, dub prompts are not displayed. For instance...
kheaser@IT-ASST-SB MINGW64 /c/Users/kheaser/Git/Delivery/projects (master) $ dub init 00_01_print_ogl_ver ... All this white space here is me just pressing the Enter key ... to get the default values. Package recipe format (sdl/json) [json]: Name [00_01_print_ogl_ver]: Description [A minimal D application.]: Author name [kheaser]: License [proprietary]: Copyright string [Copyright © 2017, kheaser]: Add dependency (leave empty to skip) []: Successfully created an empty project in 'C:\Users\kheaser\OneDrive for Business\GitHub\Delivery\projects\00_01_print_ogl_ver'. Package successfully created in 00_01_print_ogl_ver Any recommendations? I guess I could just run two command lines in parallel. One regular Windows command line for dub and another git bash window for GIT commands? Or should Git and Dub be kept firmly apart?
std.stdio.stderr
It appears that std.stdio.stderr does not wor exactly as stdio stderr does. In particular std.stdio.stderr.writef(…) does not work as fprintf(stderr…) does. Some code I am porting from C++ to D makes use of ANSI escape codes to go up a line and overwrite what was there, as well as change colours. This work fine in the C++ code but fails in the D code. The codes are definitely all the same, the only difference is in the writing functions. Is this problem to be expected or should it work? -- Russel. = Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder signature.asc Description: This is a digitally signed message part
Re: Need way to compare classes, and primitive types in bst Template
On Saturday, 10 June 2017 at 14:35:48 UTC, ag0aep6g wrote: ... Just that you shouldn't take my version of addNode and rely on it without double checking that it's correct. Ah, Okay. I rechecked that everything is working. The size is correct, and the membership is correct for every insert/delete. Thanks again.
Re: Need way to compare classes, and primitive types in bst Template
On 06/10/2017 06:57 AM, Mark wrote: On Friday, 9 June 2017 at 15:12:04 UTC, ag0aep6g wrote: ... Note that this is only supposed to show how to do the special casing for classes. addNode probably doesn't do exactly what it's supposed to do in your tree. I'm not sure what you mean by this? Just that you shouldn't take my version of addNode and rely on it without double checking that it's correct.
Re: Is D slow?
On Saturday, 10 June 2017 at 14:14:53 UTC, Steven Schveighoffer wrote: I can confirm on my system, ldc with bounds check off was at least twice as slow as with just -release. Definitely seems like a bug -Steve Ya, see https://github.com/ldc-developers/ldc/issues/2161
Re: Is D slow?
On Saturday, 10 June 2017 at 13:43:48 UTC, Nicholas Wilson wrote: On Saturday, 10 June 2017 at 12:44:07 UTC, Honey wrote: On Saturday, 10 June 2017 at 12:23:05 UTC, Nicholas Wilson wrote: [...] Are you saying that introducing additional checks enables the optimizer to eliminate more or more costly checks than it could without introducing those additional checks in the first place? Can you give an example? My bad I misread the original quote, misread that as performance increase. turning bounds checks off should always result in faster code. I can confirm on my system, ldc with bounds check off was at least twice as slow as with just -release. Definitely seems like a bug -Steve
Re: Is D slow?
On Saturday, 10 June 2017 at 12:44:07 UTC, Honey wrote: On Saturday, 10 June 2017 at 12:23:05 UTC, Nicholas Wilson wrote: On Saturday, 10 June 2017 at 12:16:34 UTC, Honey wrote: Is it expected that turning off bounds checking can lead to a performance decrease? Yes, with it on you are doing an "is the index <= the length" for every array access. Now some of them can be elided by the complier when it can prove that the index is always in bounds but it is generally dangerous to do so as it opens up the possibility of buffer overflow. Are you saying that introducing additional checks enables the optimizer to eliminate more or more costly checks than it could without introducing those additional checks in the first place? Can you give an example? My bad I misread the original quote, misread that as performance increase. turning bounds checks off should always result in faster code.
Re: Is D slow?
On Saturday, 10 June 2017 at 12:23:05 UTC, Nicholas Wilson wrote: On Saturday, 10 June 2017 at 12:16:34 UTC, Honey wrote: Is it expected that turning off bounds checking can lead to a performance decrease? Yes, with it on you are doing an "is the index <= the length" for every array access. Now some of them can be elided by the complier when it can prove that the index is always in bounds but it is generally dangerous to do so as it opens up the possibility of buffer overflow. Are you saying that introducing additional checks enables the optimizer to eliminate more or more costly checks than it could without introducing those additional checks in the first place? Can you give an example?
Re: Is D slow?
On Saturday, 10 June 2017 at 12:16:34 UTC, Honey wrote: On Saturday, 10 June 2017 at 11:53:44 UTC, Johan Engelen wrote: `-release` should be synonymous with `-release -boundscheck=off`. Nope it's not. http://www.digitalmars.com/d/archives/digitalmars/D/What_s_the_deal_with_-boundscheck_260237.html Thank you for clarifying that point. Is it expected that turning off bounds checking can lead to a performance decrease? Yes, with it on you are doing an "is the index <= the length" for every array access. Now some of them can be elided by the complier when it can prove that the index is always in bounds but it is generally dangerous to do so as it opens up the possibility of buffer overflow.
Re: Is D slow?
On Saturday, 10 June 2017 at 11:53:44 UTC, Johan Engelen wrote: `-release` should be synonymous with `-release -boundscheck=off`. Nope it's not. http://www.digitalmars.com/d/archives/digitalmars/D/What_s_the_deal_with_-boundscheck_260237.html Thank you for clarifying that point. Is it expected that turning off bounds checking can lead to a performance decrease?
Re: Is D slow?
On Saturday, 10 June 2017 at 10:59:24 UTC, Steven Schveighoffer
wrote:
I wrote it like this, which confirms that it's indeed
bringToFront (I tried your getTransitionIndex function, but
that didn't change timings at all):
void insertionSort(alias Less, Range)(Range r)
if (hasLength!Range && isRandomAccessRange!Range &&
hasSlicing!Range)
{
foreach (immutable i; 1 .. r.length)
{
auto ubElem = i - r[0 ..
i].assumeSorted!Less.upperBound(r[i]).length;
r[ubElem .. i+1].rotateRight;
}
}
Taking the length of upperBound is a great move! ;-)
On my mac, it's completing in about 4.4 seconds, whereas the
C++ version completes in around 3.
On my machine, I am getting the same performance even without
resorting to memmove. Using getTransitionIndex directly, however,
leads to a neglectable improvement (about 2.7 vs. 2.8 seconds),
here.
Re: Is D slow?
On Saturday, 10 June 2017 at 11:43:06 UTC, Johan Engelen wrote: On Friday, 9 June 2017 at 16:21:22 UTC, Honey wrote: What seems particularly strange to me is that -boundscheck=off leads to a performance decrease. Strange indeed. `-release` should be synonymous with `-release -boundscheck=off`. Nope it's not. http://www.digitalmars.com/d/archives/digitalmars/D/What_s_the_deal_with_-boundscheck_260237.html
Re: Is D slow?
On Friday, 9 June 2017 at 16:21:22 UTC, Honey wrote: What seems particularly strange to me is that -boundscheck=off leads to a performance decrease. Strange indeed. `-release` should be synonymous with `-release -boundscheck=off`. Investigating... - Johan
Re: Is D slow?
On 6/10/17 5:00 AM, Honey wrote:
On Friday, 9 June 2017 at 23:10:28 UTC, Ali Çehreli wrote:
You would get the exact performance if you implemented e.g. with
pointers. Your test has been very valuable for exposing an
embarrassing performance issue. :)
I can confirm that, after changing implementation to the following,
performance is on par. It is not immediatetly clear to me how
r[r[0 .. i].getTransitionIndex!Less(r[i]) .. i + 1]
would look like if written idiomatically.
I wrote it like this, which confirms that it's indeed bringToFront (I
tried your getTransitionIndex function, but that didn't change timings
at all):
void insertionSort(alias Less, Range)(Range r)
if (hasLength!Range && isRandomAccessRange!Range && hasSlicing!Range)
{
foreach (immutable i; 1 .. r.length)
{
auto ubElem = i - r[0 ..
i].assumeSorted!Less.upperBound(r[i]).length;
r[ubElem .. i+1].rotateRight;
}
}
On my mac, it's completing in about 4.4 seconds, whereas the C++ version
completes in around 3.
Optimized your rotateRight a bit to get better performance when we can
use memmove:
void rotateRight(Range)(Range r)
if (hasLength!Range && isRandomAccessRange!Range && hasSlicing!Range)
{
auto t = r[$ - 1];
static if(isDynamicArray!Range)
{
import core.stdc.string;
memmove(r.ptr + 1, r.ptr, (r.length - 1) * r[0].sizeof);
}
else
{
foreach_reverse (i; 0 .. r.length - 1)
{
r[i + 1] = r[i];
}
}
r[0] = t;
}
Brings it to exactly c++ performance :)
I'll update the bug report.
-Steve
Re: What is the best way to include this file from the runtime libraries?
On Saturday, 10 June 2017 at 10:07:54 UTC, rikki cattermole wrote: You found it. Ok Thanks :)
Re: What is the best way to include this file from the runtime libraries?
On 10/06/2017 11:06 AM, ulyssesdwolfe wrote: Hi I am trying to hook up an app to log to /var/log through the rsyslog daemon and it seems I need this file https://github.com/dlang/druntime/blob/master/src/core/sys/posix/syslog.d but I am not sure what the correct way to include files from the runtime libs is. Right now I am just doing import core.sys.posix.syslog; You found it.
What is the best way to include this file from the runtime libraries?
Hi I am trying to hook up an app to log to /var/log through the rsyslog daemon and it seems I need this file https://github.com/dlang/druntime/blob/master/src/core/sys/posix/syslog.d but I am not sure what the correct way to include files from the runtime libs is. Right now I am just doing import core.sys.posix.syslog; and that works but I was hoping to get clarified on what is the best method for this is? ty
Re: Is D slow?
On Friday, 9 June 2017 at 23:10:28 UTC, Ali Çehreli wrote:
You would get the exact performance if you implemented e.g.
with pointers. Your test has been very valuable for exposing an
embarrassing performance issue. :)
I can confirm that, after changing implementation to the
following, performance is on par. It is not immediatetly clear to
me how
r[r[0 .. i].getTransitionIndex!Less(r[i]) .. i + 1]
would look like if written idiomatically.
size_t getTransitionIndex(alias test, Range, V)(Range r, V v)
if (isRandomAccessRange!Range && hasLength!Range)
{
size_t first = 0;
size_t count = r.length;
while (count > 0)
{
immutable step = count / 2;
immutable it = first + step;
if (!test(v, r[it]))
{
first = it + 1;
count -= step + 1;
}
else
{
count = step;
}
}
return first;
}
void rotateRight(Range)(Range r)
if (hasLength!Range && isRandomAccessRange!Range &&
hasSlicing!Range)
{
auto t = r[$ - 1];
foreach_reverse (i; 0 .. r.length - 1)
{
r[i + 1] = r[i];
}
r[0] = t;
}
void insertionSort(alias Less, Range)(Range r)
if (hasLength!Range && isRandomAccessRange!Range &&
hasSlicing!Range)
{
foreach (i; 1 .. r.length)
{
rotateRight(r[r[0 .. i].getTransitionIndex!Less(r[i]) .. i
+ 1]);
}
}
