Re: drepl fails because of missing lib linenoise
On Thursday, 8 December 2016 at 12:31:01 UTC, Nordlöw wrote: drepl fails to build as https://github.com/drepl/drepl/issues/58 Any ideas why? Looks like you don't have liblinenoise installed. Some basic notes on how to install on linux/macosx can be found here: https://github.com/BlackEdder/todod#linenoise
Re: Compiling and linking libraries
On Wednesday, 16 November 2016 at 14:27:41 UTC, Darren wrote:
Hey all,
This is a very beginner problem, but not one I know how to do
on my own. Could anyone give a step-by-step guide on how to
compile libraries, and then use them in my project with DUB?
If you are happy to use dub I would just add the GL library as a
dependency to my dub.json file. Then if you call dub it will
download and compile the necessary file.
Example dub.json file:
```
{
"name": "myWindow",
"authors": [
"Darren"
],
"description": "A minimal D application.",
"copyright": "Copyright © 2016, Darren",
"dependencies": {
"derelict-gl3": "~>2.0.0-alpha.2"
}
}
```
This will build the necessary library into your library though,
so it is not the same as using a static library.
Also see the "Creating an own project" section on
https://code.dlang.org/getting_started
Re: problem with isnan
On Thursday, 10 November 2016 at 23:45:01 UTC, Charles Hixson wrote: you might try using std.math.isNaN instead and see what it does. It was default initialized by the class instance: classCell ... floatcurActivation; ... The this method doesn't have any mention of a few variables that are supposed to be default initialized, or which curActivation is one. std.math.isNaN should work for the default initialization (at least it does for doubles)
Re: Combining "chunkBy" and "until" algorithms
On Friday, 4 November 2016 at 08:04:12 UTC, Jacob Carlborg wrote: Currently I'm using a standard for loop iterating over the lines. I'm always looking at the current line and the next line. When the current line is the standard pattern and the next line is is not, I do a separate loop until I see a standard pattern again, collecting the lines with the non-standard pattern in an array. Could you filter [1] for the non standard pattern? Filter is lazy, so will only start looking for the next when the current one has been "handled". [1] https://dlang.org/phobos/std_algorithm_iteration.html#.filter
Re: Avoiding GC
On Wednesday, 26 October 2016 at 08:18:07 UTC, hardreset wrote: Is there a page somewhere on how to program D without using the GC? How do I allocate / free structs / classes on the heap manually? New would be GCed memeory wouldnt it? Delete is being depreciated? thanks. There is the following: https://wiki.dlang.org/Memory_Management
Re: From Python to Dlang
On Tuesday, 18 October 2016 at 12:03:54 UTC, Alfred Newman wrote: Hello and greetings, I'm a brand new D developer coming from Python. So, can you pls guys suggest me any resource like "D for a Python Developer" or so ? BTW, I just ordered the "D Programming Language" book from AA. Cheers Another great book, available for free online: http://ddili.org/ders/d.en/index.html
Re: polar coordinates with ggplotd
On Sunday, 18 September 2016 at 22:13:35 UTC, brocolis wrote: Found an error in ys line. Thanks. Does that mean you solved it? Currently there is no special support for other coordinate systems, but I recently added Guides for x/y coordinates which should make this relatively straightforward to implement and is next on the list. Not sure when I'll get a chunk of time to implement it though. For now you will have to convert the coordinates yourself, before plotting them.
Re: Draw math formulas with ggplotd
On Saturday, 17 September 2016 at 11:57:17 UTC, John Colvin wrote: On Saturday, 17 September 2016 at 11:45:07 UTC, Edwin van Leeuwen wrote: But I assumed he meant adding the formula onto the plot. Hah, yes, I should have read the question better. Rereading the question I am actually not sure which of us interpreted the question correctly :) Do you support embedding outside images? When I wanted nice mathematical notation generated quickly in D I have used pyd to call matplotlib's builtin math rendering (much quicker than a full latex roundtrip). You can draw onto any cairo surface, so this should be possible. You'd just need to figure out how to cast/convert a matplotlib image to a cairo image.
Re: Draw math formulas with ggplotd
On Saturday, 17 September 2016 at 11:22:04 UTC, John Colvin wrote: On Saturday, 17 September 2016 at 02:41:15 UTC, brocolis wrote: How do I draw math formulas programmatically? I want to do on screen what latex does on .pdf. And I want to draw a math formula in the image generated with ggplotd. Generate data from those formulas (I like to do this with something like iota(0, 10, 0.05).map!(x => sqrt(x) / (1 + sin(x)^^2)) and then plot that. For this part ggplotd does have a helper function: http://blackedder.github.io/ggplotd/ggplotd/stat.html#statFunction auto gg = statFunction(x => sqrt(x) / (1 + sin(x)^^2), 0.0, 10).geomLine().putIn(GGPlotD()); But I assumed he meant adding the formula onto the plot.
Re: Draw math formulas with ggplotd
On Saturday, 17 September 2016 at 09:56:09 UTC, Edwin van Leeuwen wrote: On Saturday, 17 September 2016 at 02:41:15 UTC, brocolis wrote: How do I draw math formulas programmatically? I want to do on screen what latex does on .pdf. And I want to draw a math formula in the image generated with ggplotd. You can't at the moment. Parsing latex equations is not a trivial task. When I say you can't I meant that this is not explicitly supported by ggplotd.
Re: Draw math formulas with ggplotd
On Saturday, 17 September 2016 at 02:41:15 UTC, brocolis wrote: How do I draw math formulas programmatically? I want to do on screen what latex does on .pdf. And I want to draw a math formula in the image generated with ggplotd. You can't at the moment. Parsing latex equations is not a trivial task. One possible approach would be to convert part of the equations (greek alphabet etc.) to utf and use geomLabel to "simulate" sub/super script. One caveat with this is that I am not sure how well cairo(d) supports utf.
Re: Checking all elements are unique.
On Wednesday, 31 August 2016 at 07:40:39 UTC, Dorian Haglund
wrote:
Hello,
I have an array of objects of class C which contain a id member.
I want to figure out if all the id members are unique using
functional primitives.
For example, if I have:
class C
{
int id;
}
and an array of C 'Cs';
My idea was to do:
auto ids = Cs.map!(c => c.id);
assert(equal(ids.sort().uniq(), ids.sort()));
But it doesn't compile because I can't can call sort on ids.
Any idea why ? and how to solve my initial problem, which is to
check all ids are unique.
Regards,
Dorian
Sort require an indexable array. You can convert an insertRange
to an indexable array with .array:
ids.array.sort()
You can also directly sort on id
Cs.array.sort!((a,b) => a.id < b.id);
Re: Serialize/Deserialize Tuple
On Friday, 19 August 2016 at 09:55:32 UTC, Steve Biedermann wrote: I'm trying to send data over the network. On the receiving side, I need a tuple of the sent values. Is there any way to achieve this? Depends on the format the data is send in. There are a number of serialization/deserialization libraries: binary: https://github.com/atilaneves/cerealed Others: http://code.dlang.org/search?q=serial+painlessjson+cerealed
Re: Command Line Utility Library
On Tuesday, 16 August 2016 at 13:32:26 UTC, Jacob Carlborg wrote: On 2016-08-16 11:37, Seb wrote: Manual work? O_o Just open code.dlang.org and either hit CTRL-F or use the search bar (Martin added elastic search two months ago) as the packages usually have a very low PageRank. It's a bit problematic when you don't know what to search for. Not all projects have a descriptive name ;) Does it only search the description or also the README?
Re: Command Line Utility Library
On Monday, 15 August 2016 at 07:29:58 UTC, UDW wrote: Hi, I would like some options for a library, preferably json configurable, that helps with command line tool development. Doesn't have to be in D specifically. I am using: http://code.dlang.org/packages/docopt It's not really json configurable, but that shouldn't be to complex to implement yourself.
Re: Using external libraries the correct way
On Sunday, 17 July 2016 at 17:52:59 UTC, solidstate1991 wrote: Up to this day, I have to use them by dragging the source into my project. When I tried to import imageformats, the compiler looks up for the file imageformats.d and fails to finish the program. I'm not using command line for compiling, I use Xamarin with mono-D instead. I tend to use dub for all my external libraries: http://code.dlang.org Not sure how that ties in with mono-D though.
Re: Docs for `Group` type
On Tuesday, 12 July 2016 at 11:40:48 UTC, Bahman Movaqar wrote: On 07/12/2016 01:01 PM, Mike Parker wrote: Do you have some sample code that shows the error? Yes. I'm working on Stockman[1] a playground to learn D. In file `etl.d`, line 110 [2], if I change the line to auto refInvoice = group[1].takeOne(); the file will not compile. I have attached the compile error to this message. Thanks, What does group.writeln; output? That should give you a good sense of what is going on.
Re: local const functions - bug ?
On Thursday, 7 July 2016 at 10:33:39 UTC, Basile B. wrote:
this compiles without error:
struct Foo
{
int i;
void bar()
{
void foo() const
{
i = 1;
}
foo;
}
}
In this case "const" seems to be a noop. Do you think it's a
bug ? Shouldn't "const" be applied, despite of foo()
inaccessibility ?
Is this related to:
https://issues.dlang.org/show_bug.cgi?id=1983
Re: Trying to get type and name at compile time
On Tuesday, 24 May 2016 at 18:44:45 UTC, ag0aep6g wrote: Seems to be a problem in ApplyLeft: import std.meta: AliasSeq, ApplyLeft; alias addType(T, string name) = AliasSeq!(T, name); alias addTypeInt = ApplyLeft!(addType, int); alias FullyInstantiated = addTypeInt!"foo"; Fails with: "std/meta.d(1114): Error: cannot interpret int at compile time". I've filed an issue: https://issues.dlang.org/show_bug.cgi?id=16070 Thanks! I've worked around it for now with some recursion :) Using `is(...)` with an AliasSeq of only types is ok. But you can't use it when there's a non-type in the sequence. That makes sense. Thanks for the help, Edwin
Re: Trying to get type and name at compile time
On Tuesday, 24 May 2016 at 15:09:43 UTC, Adam D. Ruppe wrote:
On Tuesday, 24 May 2016 at 15:01:33 UTC, Edwin van Leeuwen
wrote:
// I expected AliasSeq!(double,"x")???
pragma(msg,test); // tuple((double), "x")
What Phobos calls AliasSeq is called tuple inside the compiler.
They are the same thing, just different names.
That's what I assumed at first.. So why does the following fail
with: cannot interpret double at compile time? I assumed
staticMap would automatically flatten the resulting AliasSeqs.
```
import std.meta : AliasSeq, ApplyLeft, staticMap;
struct Point { double x; double y; }
template addType(T,alias name)
{
alias addType = AliasSeq!( typeof(__traits(getMember, Point,
name)),
name );
}
alias test3 = addType!( Point, "x" );
// I expected AliasSeq!(double,"x")???
pragma(msg,test3); // tuple((double), "x")
//static assert(is(test == AliasSeq!(double,"x")));
alias ts = AliasSeq!("x","y");
alias addTypeP = ApplyLeft!(addType,Point);
alias mapped = staticMap!(addTypeP,ts);
pragma(msg,mapped);
void main() {
}
```
Looking at it now, I guess it is because staticMap does not work
with alias values, only with actual type lists. Is that correct?
Any ideas on how to do this?
static assert(is(test == AliasSeq!(double,"x")));
AliasSeq is not comparable as a type. You can test the
individual pieces of it (`is(test[0] == double) && test[1] ==
"x"`) or wrap it in a struct or something.
I thought so, but a lot of the documentation does seem to compare
it (see the example here):
https://dlang.org/library/std/meta/static_map.html
Trying to get type and name at compile time
Hi all,
I am trying to get the type and name of a field at compile time,
but can't get the following to work. Anyone any idea of why test
is not of the type AliasSeq!(double, "x")?
```
import std.meta : AliasSeq;
struct Point { double x; double y; }
alias test = AliasSeq!(
typeof(__traits(getMember, Point, "x")),
"x"
);
// I expected AliasSeq!(double,"x")???
pragma(msg,test); // tuple((double), "x")
static assert(is(test == AliasSeq!(double,"x")));
void main() {}
```
Cheers, Edwin
Re: static member and/or @property ?
On Thursday, 19 May 2016 at 15:12:44 UTC, Edwin van Leeuwen wrote: On Thursday, 19 May 2016 at 15:04:00 UTC, chmike wrote: The only viable solution I found so far is by using distinct member names. In the interface we define name as a property, and in the class we define the static member with another name. Is it possible to avoid the different names ? Can you use identifier!(typeof(this)) or something along those lines. I am not sure how it behaves with inheritance. https://dlang.org/spec/traits.html#identifier Sorry I meant __traits(identifier, typeof(this)).
Re: static member and/or @property ?
On Thursday, 19 May 2016 at 15:04:00 UTC, chmike wrote: The only viable solution I found so far is by using distinct member names. In the interface we define name as a property, and in the class we define the static member with another name. Is it possible to avoid the different names ? Can you use identifier!(typeof(this)) or something along those lines. I am not sure how it behaves with inheritance. https://dlang.org/spec/traits.html#identifier
Re: Compile Tango for DMD2 - Any instructions how to do it?
On Wednesday, 18 May 2016 at 16:37:48 UTC, TheDGuy wrote: On Wednesday, 18 May 2016 at 16:13:35 UTC, Seb wrote: May I ask why you need to get tango working? It has been deprecated a long time ago and phobos (the standard library) or alternatively other packages on dub have a look of features :) Okay, it looks like 'onyx' is a library which handles serial communication in D. So tried to create a new project with DUB and add onyx as dependency but there are still some errors: http://pastebin.com/4eRBt6XX Any idea what i do wrong? The onyx README seems to suggest it only works for POSIX. Did you try serial-port by any chance: http://code.dlang.org/packages/serial-port That does mention Windows as supported. It is quite old though, the latest github activity is from a year ago.
Re: static import (v2.071.0)
On Wednesday, 11 May 2016 at 14:24:03 UTC, Chris wrote: I was wondering if `static import std.file;` `if (exists(file))` will only import `std.file.exists` or the whole lot of `std.file`? I want to find out what the best strategy for imports is now. I tend to do specified imports, although (AFAIK) it doesn't make a difference for the imported code: private import std.file : exists; if (exists(file))
Re: ggplotd - curve colour
On Monday, 9 May 2016 at 02:29:47 UTC, brocolis wrote:
Is this correct usage?
auto gg = GGPlotD().put( geomLine( Aes!(typeof(xs), "x",
typeof(ysfit), "y", string, "colour")( xs, ysfit, "red") ) );
The output is a blank png file.
Full source:
import ggplotd.ggplotd;
import ggplotd.geom;
import ggplotd.aes;
import ggplotd.axes;
void main()
{
import std.array : array;
import std.algorithm : map;
import std.range : iota;
import ggplotd.colour;
auto f = (double x) { return x; };
auto xs = iota(-5, 5, 0.1 ).array;
auto ysfit = xs.map!((x) => f(x)).array;
auto gg = GGPlotD().put( geomLine( Aes!(typeof(xs), "x",
typeof(ysfit), "y", string, "colour")( xs, ysfit, "red") ) );
gg.put( xaxisOffset( 0) ).put( yaxisOffset( 0) );
gg.save( "axes.png", 500, 300 );
}
The problem there is that colour also needs to be an InputRange.
This is so that different points can have a different colours
associated with it, which is particularly useful if you want to
plot some data and have different types of data plotted as
different colours.
In your example you can either do:
```
auto colour = "red".repeat( xs.length );
auto gg = GGPlotD().put( geomLine( Aes!(typeof(xs), "x",
typeof(ysfit), "y", typeof(colour), "colour")( xs, ysfit,
colour) ) );
```
Or use the mergeRange function mentioned before, which will
automatically repeat if one argument is a single element.
```
auto aes = Tuple!( string, "colour" )( "red" ).mergeRange(
Aes!(typeof(xs), "x",
typeof(ysfit), "y" )( xs, ysfit ) );
```
Re: ggplotd - curve colour
On Sunday, 8 May 2016 at 01:50:38 UTC, brocolis wrote:
How do I set the color of a curve with ggplotd?
Thanks.
Also see the below example on how to merge Colour with an
existing range of points using mergeRange:
(Copied from http://blackedder.github.io/ggplotd/stat.html)
void main()
{
/// http://blackedder.github.io/ggplotd/images/function.png
import std.random : uniform;
import std.typecons : Tuple;
import ggplotd.stat : statFunction;
import ggplotd.ggplotd : GGPlotD;
import ggplotd.geom : geomLine, geomPoint;
import ggplotd.aes : mergeRange;
auto f = (double x) { return x / (1 + x); };
auto aes = statFunction(f, 0.0, 10);
auto gg = GGPlotD().put(geomLine(aes));
// Generate some noisy points
auto f2 = (double x) { return x / (1 + x) * uniform(0.75,
1.25); };
auto aes2 = f2.statFunction(0.0, 10, 25);
// Show points in different colour
auto withColour = Tuple!(string,
"colour")("aquamarine").mergeRange(aes2);
gg = gg.put(withColour.geomPoint);
gg.save("function.png");
}
Re: ggplotd - curve colour
On Sunday, 8 May 2016 at 01:50:38 UTC, brocolis wrote: How do I set the color of a curve with ggplotd? Thanks. You can set colours by name: https://github.com/BlackEdder/ggplotd/blob/master/source/ggplotd/colour.d#L20 Alternatively you can pass through the RGB value (see the link above for the specification). Finally if you have multiple curves and don't want to specify specific colours you can just give them a different identifier (e.g. different double/int value (any type should do)) and it will chose the colours according to the colourgradient used. There is an example on how to specify your own gradient in the hist3D.svg example: http://blackedder.github.io/ggplotd/ggplotd.html
Re: DUB and pragma lib - OSX
On Wednesday, 20 April 2016 at 05:53:28 UTC, Joel wrote: How do I get this C stuff working with DUB? Mind posting your dub configuration file?
Re: JSONValue floating and 42
On Tuesday, 19 April 2016 at 13:44:08 UTC, Andre wrote: -> I need to analyze every value whether it is a floating or an integer? This is the correct option. Something like: double f; if (j["value"].type == JSON_TYPE.INTEGER) f = j["value"].integer.to!float; else f = j["value"].floating; There are also a number of libraries available that make dealing with json a bit easier: code.dlang.org/search?q=json
Re: simple range question
On Friday, 8 April 2016 at 18:27:59 UTC, Laeeth Isharc wrote: suppose I have a forward or random access range. what's the best way to compare each element with the element 4 elements prior to that element? I could map each element to a tuple of the element and the element 4 bars previously and do it that way. any neater way ? I'd do it like this, but I guess that is what you mean with mapping it to a tuple: zip( r, r[4..$] ).map!((t) => t[0] == t[1]);
Re: is std.algorithm.joiner lazy?
On Thursday, 7 April 2016 at 09:55:56 UTC, Puming wrote:
When compiled, I get the error:
Error: open path skips field __caches_field_0
source/app.d(19, 36): Error: template instance
std.algorithm.iteration.cache!(MapResult!(__lambda1, int[]))
error instantiating
That seems like a bug to me and you might want to submit it to
the bug tracker. Even converting it to an array first does not
seem to work:
import std.stdio : writeln;
import std.algorithm : map, cache, joiner;
import std.array : array;
auto read(int a) {
return [0, a]; // second level
}
auto mkarray(int a) {
return [-a, a].map!(x=>read(x)).cache.joiner; // to avoid
calling read twice
}
void main() {
auto xs = [1,2 ,3, 4];
auto r = xs.map!(x=>mkarray(x)).array;
// Both lines below should be equal, but second does not compile
[[0, -1, 0, 1], [0, -2, 0, 2], [0, -3, 0, 3], [0, -4, 0,
4]].cache.joiner.writeln;
r.cache.joiner.writeln;
}
Above results in following error:
/opt/compilers/dmd2/include/std/algorithm/iteration.d(326):
Error: one path skips field __caches_field_0
/d617/f62.d(19): Error: template instance
std.algorithm.iteration.cache!(Result[]) error instantiating
Re: is std.algorithm.joiner lazy?
On Thursday, 7 April 2016 at 08:17:38 UTC, Puming wrote: On Thursday, 7 April 2016 at 08:07:12 UTC, Edwin van Leeuwen wrote: OK. Even if it consumes the first two elements, then why does it have to consume them AGAIN when actually used? If the function mkarray has side effects, it could lead to problems. After some testing it seems to get each element twice, calls front on the MapResult twice, on each element. The first two mkarray are both for first element, the second two for the second. You can solve this by caching the front call with: xs.map!(x=>mkarray(x)).cache.joiner;
Re: is std.algorithm.joiner lazy?
On Thursday, 7 April 2016 at 07:07:40 UTC, Puming wrote:
Hi:
when I use map with joiner, I found that function in map are
called. In the document it says joiner is lazy, so why is the
function called?
say:
int[] mkarray(int a) {
writeln("mkarray called!");
return [a * 2]; // just for test
}
void main() {
auto xs = [1, 2];
auto r = xs.map!(x=>mkarray(x)).joiner;
}
running this will get the output:
mkarray called!
mkarray called!
I suppose joiner does not consume?
when I actually consume the result by writlen, I get more
output:
mkarray called!
mkarray called!
[2mkarray called!
mkarray called!
, 4]
I don't understand
Apparently it works processing the first two elements at
creation. All the other elements will be processed lazily.
Even when a range is lazy the algorithm still often has to
"consume" one or two starting elements, just to set initial
conditions. It does surprise me that joiner needs to process the
first two, would have to look at the implementation why.
Re: how to parse a string into a phobos datatype with additional logic
On Thursday, 7 April 2016 at 07:45:06 UTC, yawniek wrote: what is the way one is supposed to parse e.g. a double of unixtime (as delived by nginx logs) into a SysTime? currently i'm creating a wrapper struct around SysTime with alias this as: https://gist.github.com/yannick/6caf5a5184beea0c24f35d9d4a4c7783 really ugly imho. is there a better way to do this? You can try this library: https://code.dlang.org/packages/dateparser
Re: Read only delegate
On Monday, 4 April 2016 at 11:39:55 UTC, Kagamin wrote: On Monday, 4 April 2016 at 11:32:23 UTC, Rene Zwanenburg wrote: https://issues.dlang.org/show_bug.cgi?id=1983 Bug 1983 is about usage of delegates after creation, restrictions during creation are enforced. AIU, OP wants to have const check during creation. I think the underlying issue is the same. The problem seems to be that: Unfortunately, there is no way to declare a const delegate (by which I mean, a delegate whose context pointer is typed const). I actually discovered the problem, due to the hole it leaves in the const system, where I got different results calling a const method multiple times. The const method in question called a delegate that changed its context pointer, resulting in changes during calls.
Re: Read only delegate
On Monday, 4 April 2016 at 11:32:23 UTC, Rene Zwanenburg wrote: On Monday, 4 April 2016 at 08:10:10 UTC, Edwin van Leeuwen wrote: Is there a way to make sure a delegate only reads state, without changing it? I tried annotating the delegate as const, but that does not seem to work. ``` Yeah this is a nasty old issue. The underlying problem is that a delegate's function and context pointers are completely untyped. https://issues.dlang.org/show_bug.cgi?id=1983 Thanks for the reference, hopefully this will be resolved at some point :)
Re: Read only delegate
On Monday, 4 April 2016 at 08:10:10 UTC, Edwin van Leeuwen wrote:
Is there a way to make sure a delegate only reads state,
without changing it? I tried annotating the delegate as const,
but that does not seem to work.
Note that annotating with pure also doesn't help. As a result we
can have a pure delegate that returns different results every
time it is called.
```D
void main()
{
import std.stdio : writeln;
auto r = [0,1,2,3];
auto f = delegate() const pure
{
import std.array : front, popFront;
r.popFront;
return r.front;
};
r.writeln; // [0,1,2,3]
auto f1 = f();
r.writeln; // [1,2,3]
assert( f() == f1 ); // Throws
}
```
Read only delegate
Is there a way to make sure a delegate only reads state, without
changing it? I tried annotating the delegate as const, but that
does not seem to work.
```D
void main()
{
import std.stdio : writeln;
auto r = [0,1,2,3];
auto f = delegate() const // Compiles even though we are
changing r
{
import std.array : popFront;
r.popFront;
};
r.writeln; // [0,1,2,3]
f();
r.writeln; // [1,2,3]
}
```
Re: infer type argument in classe constructor?
On Tuesday, 29 March 2016 at 10:13:28 UTC, Puming wrote:
Hi,
I'm writing a generic class：
```d
struct Message { ... }
class Decoder(MsgSrc) {
}
```
When using it, I'd have to include the type of its argument:
```
void main() {
Message[] src = ...;
auto decoder = new Decoder!(Message[])(src);
...
}
```
Can it be inferred so that I only need to write?
```d
auto decoder = new Decoder(src); // you can infer the type from
src.
```
You can't directly. This is (AFAIK) because this()() can also be
templated, making it impossible to just derive. The common way in
D to deal with this/work around it is to create a helper function
that can infer it:
```D
auto decoder(T)(T src)
{
return new Decoder!T(src);
}
auto dec = decoder(src)
```
This pattern is widely used in phobos (e.g. tuple and Tuple)
Re: Usage of custom class with JSONValue
On Thursday, 24 March 2016 at 11:39:13 UTC, arturg wrote: isnt alias this supposed to do this implicitly? convert this auto jsValue = JSONValue(new MyClass()); into this auto jsValue = JSONValue((new MyClass())._data); Good point, I did not catch that. That indeed should work and seems to be a bug. Does it work if _data is a base type (string or int, etc..)
Re: Usage of custom class with JSONValue
On Thursday, 24 March 2016 at 08:15:12 UTC, Andre wrote:
Hi,
I have a class which has already an alias this to a string
array,
so I can use it in a foreach loop.
class MyClass
{
string[] _data;
alias _data this;
// ...
}
void main()
{
import std.json;
auto jsValue = JSONValue(new MyClass());
}
For some generic code I need an implicit conversion of MyClass
so I can
use it for a JSONValue. For the coding above I receive a
compiler error:
static assert "unable to convert type "MyClass" to json"
JSONValue only works with the build in types, not with user
defined types. Either you define a specific function for the
class that returns a JSONValue. Easiest way to do that would be
to build an associative array with strings as keys with the
names, and JSONValues as values and turn that into JSONValue,
i.e. (untested):
class MyClass
{
string[] _data;
alias _data this;
// ...
JSONValue toJSON()
{
JSONValue[string] aa;
JSONValue[] dataJSON = _data.map!((a) => JSONValue(a)).array;
aa["data"] = JSONValue(dataJSON);
return JSONValue(aa);
}
}
Alternatively there are multiple serialization libraries that
will allow you to turn any user defined type from and to
JSONValues.
https://code.dlang.org/packages/painlessjson
https://code.dlang.org/packages/jsonizer
Cheers, Edwin
Re: iota result as member variable
On Thursday, 24 March 2016 at 06:54:25 UTC, Alex wrote:
Hi everybody,
doing some optimization on my code, I faced some strange
question:
how to save a iota result in a class member?
Say I have
class A
{
??? member;
auto testIter4()
{
return iota(0,5);
}
}
void main()
{
A a = new A();
a.member = testIter4();
}
how would I declare the member?
Yeah this is one of the downsides of voldermort types. In these
cases typeof and ReturnType are your friend. It often takes me a
couple of tries to get it right, but the following seems to work:
import std.traits : ReturnType;
import std.range : iota;
class A
{
ReturnType!(A.testIter4) member;
auto testIter4()
{
return iota(0,5);
}
}
void main()
{
A a = new A();
a.member = a.testIter4();
}
Re: Something wrong with GC
On Tuesday, 22 March 2016 at 13:46:41 UTC, stunaep wrote:
public class Example2 {
private int one;
private int two;
public this(int one, int two) {
this.one = one;
this.two = two;
}
}
in a tree map and list of some sort. Neither of the above work
whether they are classes or structs and it's starting to become
quite bothersome...
Is there a particular reason why you don't want to use the
standard ranges?
public class Example2 {
private int one;
private int two;
public this(int one, int two) {
this.one = one;
this.two = two;
}
}
void main()
{
auto myExamplesList = [ new Example2( 6,3 ), new Example2(7,5) ];
// Note that if you do a lot of appending then using
Appender is more performant than ~=
myExamplesList ~= new Example2(9,1);
}
For trees there is also redBlackTree
Re: Gdmd compiling error
On Wednesday, 16 March 2016 at 12:17:42 UTC, Orkhan wrote: On Tuesday, 15 March 2016 at 18:26:48 UTC, Ali Çehreli wrote: I don't know where from shpuld I get help. Thanks. Is the xcomm library available somewhere, maybe if we had a link to the original documentation we could help.
Re: Obtaining argument names in (variadic) functions
On Wednesday, 16 March 2016 at 20:53:42 UTC, JR wrote:
void printVars(Args...)()
if (Args.length > 0)
{
import std.stdio : writefln;
foreach (i, arg; Args) {
writefln("%s\t%s:\t%s", typeof(Args[i]).stringof,
Args[i].stringof, arg);
}
}
void main() {
int abc = 3;
string def = "58";
float ghi = 3.14f;
double jkl = 3.14;
printVars!(abc,def,ghi,jkl)();
}
Interesting, any idea if it is possible to do assignment within
template.. Either:
printVars!(int abc=5,string def="58")();
or something like
printVars!("abc","def",ghi)(5,"58");
Re: Obtaining argument names in (variadic) functions
On Thursday, 17 March 2016 at 13:53:00 UTC, JR wrote:
Interesting, any idea if it is possible to do assignment
within template.. Either:
printVars!(int abc=5,string def="58")();
or something like
printVars!("abc","def",ghi)(5,"58");
What would the use-cases for those be?
I don't think the first is valid grammar, and I'm not sure what
you want the second to do. Resolve symbols by string literals
of their names? That might need a string mixin as they wouldn't
be in scope when in the called template function, but I've
never tried it.
Both use cases are when you want a named parameter, without
having to assign it first. I know the first is not valid grammar,
was just wondering if you might be smarter than me and see a way
to make it valid :)
Second one is another possible alternative that I have been
thinking about.
Basically, say I want to have the named (optional) parameters x
and y. In your initial example I would be required to do:
```
int x = 1;
string y = "2";
doSomethingWithNamedPars!(x,y)();
```
I just hoped to shorten that to a one liner similar to:
```
doSomethingWithNamedPars!(x=1,y="2")();
```
or alternatively
```
doSomethingWithNamedPars!("x","y")(1,"2");
```
(where doSomethingWithNamedPars's behaviour depends on which
named parameters it is passed)
Just as a reference, my current approach (in ggplotd) is with
named tuples, but that is slightly more verbose than I had hoped:
```
doSomethingWithNamedPars( Tuple!(int, "x", string, "y")( 1, 2 ) );
```
Re: How to sort a range
On Wednesday, 9 March 2016 at 15:39:55 UTC, rcorre wrote: On Wednesday, 9 March 2016 at 14:28:11 UTC, cym13 wrote: Still curious as to why it fails; maybe the range is getting copied at some point? I guess I need to step through it. I did try different SwapStrategies with no luck. Since you are adapting phobos anyway you could try commenting out the assert and see what the result of the sort is. That might give you some clue: //assert(isSorted!lessFun(r), "Failed to sort range of type " ~ Range.stringof); Also I notice the line numbering is different in my sorted.d file. Did you test the latest version of dmd/phobos?
Re: How to sort a range
On Wednesday, 9 March 2016 at 13:04:31 UTC, rcorre wrote: On Wednesday, 9 March 2016 at 12:31:18 UTC, Edwin van Leeuwen wrote: On Wednesday, 9 March 2016 at 12:21:55 UTC, rcorre wrote: If you are looking for a lazy uniq that works on non sorted ranges, I implemented one not to long ago: http://github.com/BlackEdder/ggplotd/blob/master/source/ggplotd/range.d That sounds like the kind of thing I was looking for. I'll take a look, thanks! Well that one does allocate, because it keeps track of which values have already been seen. Yup, just noticed that >.< Of course it only allocates when the actual result is used, so this will probably be more efficient if you only need a small number of unique results or need to keep the unsorted range around/intact. Sorting without allocating and then using uniq should indeed be more efficient in other cases. Did you try different SwapStrategy values in your original?
Re: How to sort a range
On Wednesday, 9 March 2016 at 12:21:55 UTC, rcorre wrote: If you are looking for a lazy uniq that works on non sorted ranges, I implemented one not to long ago: http://github.com/BlackEdder/ggplotd/blob/master/source/ggplotd/range.d That sounds like the kind of thing I was looking for. I'll take a look, thanks! Well that one does allocate, because it keeps track of which values have already been seen.
Re: How to sort a range
On Wednesday, 9 March 2016 at 03:05:52 UTC, rcorre wrote: I was in a situation where I wanted to remove duplicates from an OnlyResult. To do this with uniq, I needed to sort it. OnlyResult doesn't satisfy the template constraints of sort, but this seems easy enough to fix. I made front, back, and opIndex return by ref. With this, the following compiles: assert(only(3,1,2).sort.equal(only(1,2,3))); However, it fails with: core.exception.AssertError@std/algorithm/sorting.d(1052): Failed to sort range of type OnlyResult!(int, 3LU) So, if you have a range for which sort compiles, what does it take to make sorting actually work? For reference, my two attempts were: https://github.com/rcorre/phobos/commit/d89b3cfab7a0938e178a506b4ceb8faae6ecbfe2 https://github.com/rcorre/phobos/commit/512d9b8db6f311db6a9b6ccb077a691cec66ce70 I'm not sure why your fix didn't work, but generally I work around this by converting the OnlyResult into an array: import std.array : array; assert(only(3,1,2).array.sort.equal(only(1,2,3))); If you are looking for a lazy uniq that works on non sorted ranges, I implemented one not to long ago: http://github.com/BlackEdder/ggplotd/blob/master/source/ggplotd/range.d
Re: Memory Efficient HashSet
On Tuesday, 8 March 2016 at 08:12:04 UTC, Nordlöw wrote:
Has anybody put together a memory-efficient D-implementation of
a HashSet
Something like
sparse_hash_set<> contained in
https://github.com/sparsehash/sparsehash
but in D.
There is an implementation in:
code.dlang.org/packages/emsi_containers
But to be honest I got stuck trying to use it (copy constructor
disabled), so I used this very minimal wrapper around associative
array:
private struct HashSet(E) {
// TODO switch to proper implementation (not using AA)
bool put( E el )
{
if ( el in set )
return false;
set[el] = set.length;
return true;
}
size_t[E] set;
}
(I only needed put, since I used it to check whether we already
encountered a value before in a lazy/non sorted implementation of
uniq)
Re: Warning: statement is not reachable
On Tuesday, 1 March 2016 at 21:30:44 UTC, Tamas wrote:
foreach(attr; __traits(getAttributes, S)) {
static if (is(attr == Tag)) {
return true;
}
}
return false;
}();
}
void main() {
static @Tag struct MyStruct {}
static struct VanillaStruct {}
static assert(isTagged!MyStruct);
static assert(!isTagged!VanillaStruct);
}
Sorry forgot to add the fix to the email. The following should
work:
bool tag = false;
foreach(attr; __traits(getAttributes, S)) {
static if (is(attr == Tag)) {
tag = true;
}
}
return tag;
Re: Warning: statement is not reachable
On Tuesday, 1 March 2016 at 21:30:44 UTC, Tamas wrote:
My d code doesn't compile using ldc2 1.0.0-alpha or anything
above DMD v2.068.0
Using these compilers I get a lot of "Warning: statement is not
reachable". Then the both compiler crashes.
ldc2 -w reach.d
dmd -w reach.d
reach.d:
struct Tag {}
template isTagged(S) {
enum bool isTagged =
delegate() {
foreach(attr; __traits(getAttributes, S)) {
static if (is(attr == Tag)) {
return true;
}
}
return false;
}();
}
void main() {
static @Tag struct MyStruct {}
static struct VanillaStruct {}
static assert(isTagged!MyStruct);
static assert(!isTagged!VanillaStruct);
}
We had the same problem in painlessjson and you can find some
more background (with our fix) on it here:
https://github.com/BlackEdder/painlessjson/issues/49
As I understand it: if attr == Tag the code will look something
like this:
foreach(attr; __traits(getAttributes, S)) {
return true;
}
return false;
and the return false is basically unreachable.
Re: Why file.exists of relative path on Linux always return false?
On Monday, 29 February 2016 at 14:58:46 UTC, Alex Parrill wrote:
On Monday, 29 February 2016 at 14:50:51 UTC, Suliman wrote:
I am trying to check relative path on Linux for exists.
string mypath = "~/Documents/imgs";
~ is expanded by your shell. It is not a relative path, and
system calls do not recognize it (same with environmental
variables).
D can expand tilde with expandTilde:
import std.path : expandTilde;
string mypath = expandTilde("~/Documents/imgs");
Re: Am I right understand the dub.json system?
On Monday, 29 February 2016 at 12:45:36 UTC, Suliman wrote:
On Monday, 29 February 2016 at 12:34:02 UTC, Edwin van Leeuwen
wrote:
Should it be like this?
http://www.everfall.com/paste/id.php?80k9jsgdx6o3
"versions": ["VibeCustomMain"],
"versions": ["USE_MYSQL"],
As far as I know all versions should be on one line:
"versions": ["VibeCustomMain","USE_MYSQL"],
And by log it's again try to build sqllite.
What does the log actually say? Is it trying to bind to sqlite?
What happens if you also add
"subConfigurations": {
"ddbc":"MySQL"
}
Re: Am I right understand the dub.json system?
On Monday, 29 February 2016 at 12:27:04 UTC, Suliman wrote: For example I have got app that depended on DDBC. In configuration section DDBC related on: "libs-posix": [ "sqlite3", "pq" ] Does it's mean that it will try to find this 2 libs in any case? Even I do not use them. If I do not need them what I should to do? Fix ~/.dub/packages/ddbc and remove this strings from it, or what? Reading the dub.json from ddbc it seems you can specify which version you want. So if you only need mysql support you add "versions": ["USE_MYSQL"], in your own dub.json file.
Re: Is DUB the best place to get examples of "Best of" D code?
On Sunday, 28 February 2016 at 05:59:39 UTC, WhatMeWorry wrote: If so, is there a way to do a global search of all projects in DUB? If you just want to search through package names and descriptions you can use the search box at the top right of code.dlang.org. If you want to search through code. Most packages are on github, so you could search there (limit by D projects).
Re: Installing DUB on OSX
On Thursday, 18 February 2016 at 09:25:00 UTC, Joel wrote: On Thursday, 18 February 2016 at 08:24:34 UTC, Jacob Carlborg wrote: On 2016-02-18 08:11, Joel wrote: I had dub installed in a folder that meant I had to put 'sudo dub' to run it. I've tried to fix the problem, but where do you put it (also I tried one place, but couldn't put it in that folder)? You usually have read access to most paths. That means you should be able to run dub without sudo. Where is "dub" located? Run "which dub". It's currently in '/usr/local/bin'. How do I add it to '/usr/bin' (or what ever)? I get: Joels-MacBook-Pro:Downloads joelcnz$ cp dub /usr/bin cp: /usr/bin/dub: Operation not permitted sudo cp dub /usr/bin/ but to be honest I would delete dub (sudo rm /usr/local/bin/dub) and then try to install it with homebrew again.
Re: String joining an array of structs or class instances implementing toString?
On Thursday, 11 February 2016 at 12:44:15 UTC, pineapple wrote:
It feels like there should be an out-of-the box way to do this
but I haven't been able to find it? Help?
This is the thing that I want to do:
struct example{
const string str;
//this(string str){ this.str = str; }
string toString(){
return this.str;
}
}
public void main(){
import std.stdio;
import std.string;
example[] parts = [example("hello"), example("world")];
writeln(std.string.join(parts, " "));
}
I'd do it like this:
import std.algorithm : map;
pars.map!((part) => part.toString) // Turn them to strings
.join(" ").writeln; // Join them.
Re: String joining an array of structs or class instances implementing toString?
On Thursday, 11 February 2016 at 13:43:49 UTC, pineapple wrote: Thanks! Does the map function iterate without constructing an extra list in-memory? Yes, it is lazy, so it only calls toString when the result is actually used (by the join call). In case you do need to create an extra list you can use array as follows: import std.array : array; auto result = parts.map!((part) => part.toString).array; The call to array will "force" it to construct an array out of it.
Re: Speed of csvReader
On Friday, 22 January 2016 at 02:16:14 UTC, H. S. Teoh wrote: On Thu, Jan 21, 2016 at 04:50:12PM -0800, H. S. Teoh via Digitalmars-d-learn wrote: [...] > > https://github.com/quickfur/fastcsv [...] Fixed some boundary condition crashes and reverted doubled quote handling in unquoted fields (since those are illegal according to RFC 4810). Performance is back in the ~1200 msec range. T That's pretty impressive. Maybe turn it on into a dub package so that data pulverizer could easily test it on his data :)
Re: Speed of csvReader
On Thursday, 21 January 2016 at 09:39:30 UTC, data pulverizer
wrote:
StopWatch sw;
sw.start();
auto buffer = std.file.readText("Acquisition_2009Q2.txt");
auto records = csvReader!row_type(buffer, '|').array;
sw.stop();
Is it csvReader or readText that is slow? i.e. could you move
sw.start(); one line down (after the readText command) and see
how long just the csvReader part takes?
Re: Speed of csvReader
On Thursday, 21 January 2016 at 15:17:08 UTC, data pulverizer
wrote:
On Thursday, 21 January 2016 at 14:56:13 UTC, Saurabh Das wrote:
@Edwin van Leeuwen The csvReader is what takes the most time,
the readText takes 0.229 s
The underlying problem most likely is that csvReader has (AFAIK)
never been properly optimized/profiled (very old piece of the
library). You could try to implement a rough csvReader using
buffer.byLine() and for each line use split("|") to split at "|".
That should be faster, because it doesn't do any checking.
Non tested code:
string[][] res = buffer.byLine().map!((a) =>
a.split("|").array).array;
Re: CMake support for D
On Monday, 4 January 2016 at 12:40:23 UTC, Dibyendu Majumdar wrote: Thanks for suggesting dub, will check it out. Also premake seems to support D so that is another option. Another alternative is reggae which supports mixed code base: https://github.com/atilaneves/reggae and can generate ninja/make/tup build rules (similarly to cmake).
Re: my first D program (and benchmark against perl)
On Wednesday, 11 November 2015 at 13:32:00 UTC, perlancar wrote:
for (int rownum=0; rownum < table.length; rownum++) {
res ~= "|";
for (int colnum=0; colnum < table[rownum].length;
colnum++) {
res ~= leftJustify(table[rownum][colnum],
widths[colnum]);
res ~= "|";
}
res ~= "\n";
Not sure if this will be faster, but you could try rewriting the
above for loop
with more functional code (code below is untested):
table.map!((col)
{ return zip(col,widths)
.map!( (e) => leftJustify(e[0], e[1] ) )
.join("|");
}).join("\n");
Cheers,
Edwin
Re: foreach loop
On Tuesday, 3 November 2015 at 15:29:31 UTC, Namal wrote:
writefln("Count is: %s", arr
.filter!(a => a==true)
.sum);
// Note: std.algorithm.sum is the same as
// std.algorithm.reduce!((a,b)=a+b);
Shouldn't you be using walkLength instead of sum, since you are
counting the left over values?
import std.range : walkLength;
writefln("Count is: %s", arr
.filter!(a => a==false)
.walkLength);
Re: foreach loop
On Tuesday, 3 November 2015 at 16:55:44 UTC, wobbles wrote:
On Tuesday, 3 November 2015 at 15:42:16 UTC, Edwin van Leeuwen
wrote:
On Tuesday, 3 November 2015 at 15:29:31 UTC, Namal wrote:
writefln("Count is: %s", arr
.filter!(a => a==true)
.sum);
// Note: std.algorithm.sum is the same as
// std.algorithm.reduce!((a,b)=a+b);
Shouldn't you be using walkLength instead of sum, since you
are counting the left over values?
import std.range : walkLength;
writefln("Count is: %s", arr
.filter!(a => a==false)
.walkLength);
That would work also yes.
Be interesting to know which is more efficient actually - I
suspect they're very similar.
false converts to zero, so
[false,false,false].sum == 0
Of course true converts to one ->
[true,true,true].sum == 3
Re: Merging two named Tuples
On Saturday, 24 October 2015 at 11:04:14 UTC, Edwin van Leeuwen
wrote:
I am trying to write a function to merge two named structs, but
am completely stuck on how to do that and was wondering if
anyone good provide any help. I know I can access the different
names with tup.fieldNames, but basically can't work out how to
use that to build the new return type. Below is an outline of
what I am trying to do (with unittest). Any pointers would be
greatly appreciated.
I tried the following, but get a compile error:
source/ggplotd/aes.d(633): Error: variable tup cannot be read at
compile time
source/ggplotd/aes.d(633): Error: argument to mixin must be a
string, not (__error)
source/ggplotd/aes.d(646): Error: template instance
ggplotd.aes.merge!(Tuple!(string[], "x", string[], "y", string[],
"label"), Tuple!(double[], "x", double[], "y")) error
instantiating
import std.typecons : Tuple;
template merge(T, U)
{
auto merge( T base, U other )
{
string typing = "Tuple!(";
string variables = "(";
foreach( i, t; other.fieldNames )
{
typing ~= other.Types[i].stringof ~ ",\"" ~ t ~ "\",";
variables ~= "other." ~ t ~ ",";
}
foreach( i, t; base.fieldNames )
{
bool contains = false;
foreach( _, t2; other.fieldNames )
{
if (t==t2)
contains = true;
}
if (!contains)
{
typing ~= base.Types[i].stringof ~ ",\"" ~ t ~
"\",";
variables ~= "base." ~ t ~ ",";
}
}
string tup = typing[0..$-1] ~ ")" ~ variables[0..$-1] ~
");";
// Do some clever CTFE
return mixin(tup);
}
}
///
unittest
{
auto xs = ["a","b"];
auto ys = ["c","d"];
auto labels = ["e","f"];
auto aes = Tuple!(string[], "x", string[], "y", string[],
"label")(
xs, ys, labels );
auto nlAes = merge( aes, Tuple!(double[], "x",
double[], "y" )(
[0,1], [3,4] ) );
assertEqual( nlAes.x[0], 0 );
assertEqual( nlAes.label.front, "e" );
}
I guess fieldNames does not exist at compile time? Can I get the
fieldNames etc at compile time?
Cheers, Edwin
Re: Merging two named Tuples
On Thursday, 29 October 2015 at 19:42:10 UTC, anonymous wrote: `tup` is an ordinary (run time, dynamic) string to the type system. You can't mixin those. You can only mixin static values (enum, static immutable, CTFE results). The code you're generating doesn't depend on `base` and `other`. All it needs are `T` and `U`. So, you can generate the code from the types and mix it into a function that takes `T base, U other`: Thanks :) That worked perfectly.
Merging two named Tuples
I am trying to write a function to merge two named structs, but
am completely stuck on how to do that and was wondering if anyone
good provide any help. I know I can access the different names
with tup.fieldNames, but basically can't work out how to use that
to build the new return type. Below is an outline of what I am
trying to do (with unittest). Any pointers would be greatly
appreciated.
/++
Merge two Aes structs
If it has similar named types, then it uses the second one.
Returns a new struct, with combined types.
+/
import std.typecons : Tuple;
template merge(T, U)
{
auto merge( T base, U other )
{
// Go over other.fieldNames and collect them for new tuple
// Go over base.fieldNames, ignoring the ones that other
has as well
// Build newTuple
return newTuple;
}
}
///
unittest
{
auto xs = ["a","b"];
auto ys = ["c","d"];
auto labels = ["e","f"];
auto aes = Tuple!(string[], "x", string[], "y", string[],
"label")(
xs, ys, labels );
auto nlAes = merge( aes, Tuple!(double[], "x",
double[], "y" )(
[0,1], [3,4] ) );
assertEqual( nlAes.x[0], 0 );
assertEqual( nlAes.label.front, "e" );
}
Re: Idiomatic adjacent_difference
On Friday, 16 October 2015 at 11:43:16 UTC, Guillaume Chatelet wrote: On Friday, 16 October 2015 at 11:38:35 UTC, John Colvin wrote: Nice ! I wanted to use lockstep(r, r.dropOne) but it doesn't return a Range :-/ It has to be used in a foreach. Instead of lockstep you can always use zip (which is the same but returns a range) zip(r, r[1..$]).map!((t) => t[1]-t[0]);
Frequent cannot deduce function from argument types
Just wondering if anyone has any tips on how to solve/avoid "cannot deduce function from argument types" when relying on template programming. I run into these problems all the time. Current one was when I tried: ``` auto ys = NumericLabel(groupedAes.front.map!((t)=>t.y)); ``` NumericLabel is a pretty minimal templated InputRange, with as only requirement on the argument that it is also an InputRange. I then get the following compile error: ``` source/ggplotd/geom.d(83,35): Error: struct ggplotd.aes.NumericLabel cannot ded uce function from argument types !()(MapResult!(__lambda2, FilterResult!(__lamb da2, Aes!(double[], "x", double[], "y", string[], "colour", candidates are: source/ggplotd/aes.d(515,1):ggplotd.aes.NumericLabel(T) if (isInputRang e!T) ``` As far as I know MapResult always returns an input range and as you can see there is only one candidate of NumericLabel, so to be honest it looks relatively straightforward to me. Now I can define the type specifically (and/or typeof) but it seems like there should be a better way. In this case typeof isn't even happy: ``` source/ggplotd/geom.d(84,17): Error: constructor ggplotd.aes.NumericLabel!(MapResult!(__lambda2, FilterResult!(__lambda2, Aes!(string[], "x", string[], "y", string[], "colour".NumericLabel.this (MapResult!(__lambda2, FilterResult!(__lambda2, Aes!(string[], "x", string[], "y", string[], "colour"))) range) is not callable using argument types (MapResult!(__lambda3, FilterResult!(__lambda2, Aes!(string[], "x", string[], "y", string[], "colour" ``` If we look closely, it expects a __lambda2 as the MapResult argument, but it gets a __lambda3. I am able to work around it by converting the mapresult to an array, but I'd rather use a lazy solution.
Re: Dub package with C code
On Thursday, 24 September 2015 at 06:21:02 UTC, Sebastiaan Koppe wrote: Because I want to focus on the product I am building right now, not on side-projects. You could try including the c source in your repo and add preBuildCommands to the dub config which builds the static library. Alternatively you could use reggea to build both.
Re: ORM libraries for D
On Thursday, 24 September 2015 at 13:24:14 UTC, Rikki Cattermole wrote: Dvorm is more or less feature complete :) I am the author of it, but unless issues come up I do not intend to continue working upon it. You could consider bumping it up to version 1.0.0 to highlight this.
Re: reading file byLine
On Friday, 18 September 2015 at 10:48:25 UTC, Namal wrote:
On Friday, 18 September 2015 at 10:34:41 UTC, Edwin van Leeuwen
wrote:
On Friday, 18 September 2015 at 10:26:46 UTC, Namal wrote:
Hello guys, is there a nice functional way to read the file
which is like
1,2,3,4,5,6
2,3,4,5,6,7
8,9,0,9,2,3
line by line, split numbers and remove each ','
convert it to int and save in a matrix int[][] arr?
Not tested, but I think the following should work:
auto matrix = str
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
And how do tell here to read my file?
Replace str with File("myfile"):
auto matrix = File("myfile")
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
Re: reading file byLine
On Friday, 18 September 2015 at 10:26:46 UTC, Namal wrote:
Hello guys, is there a nice functional way to read the file
which is like
1,2,3,4,5,6
2,3,4,5,6,7
8,9,0,9,2,3
line by line, split numbers and remove each ','
convert it to int and save in a matrix int[][] arr?
Not tested, but I think the following should work:
auto matrix = str
.byLine
.map!((l) => l.split(",")// Split each line
.map!(to!int) // Turn into ints
.array)// Return an array
.array // Copy into an array
Re: reading file byLine
On Friday, 18 September 2015 at 12:28:29 UTC, Namal wrote:
So do I understand it right: does => in map! indicates a
lambda function?
Yes exactly. There are a number of ways you can define a lambda
function in D. For example if the function is multiline I often
use:
(l) {
...; // do something
return result;
}
More details here http://ddili.org/ders/d.en/lambda.html (half
way down the page)
Re: Speeding up text file parser (BLAST tabular format)
On Monday, 14 September 2015 at 12:50:03 UTC, Fredrik Boulund wrote: On Monday, 14 September 2015 at 12:44:22 UTC, Edwin van Leeuwen wrote: Sounds like this program is actually IO bound. In that case I would not expect a really expect an improvement by using D. What is the CPU usage like when you run this program? Also which dmd version are you using. I think there were some performance improvements for file reading in the latest version (2.068) Hi Edwin, thanks for your quick reply! I'm using v2.068.1; I actually got inspired to try this out after skimming the changelog :). Regarding if it is IO-bound. I actually expected it would be, but both the Python and the D-version consume 100% CPU while running, and just copying the file around only takes a few seconds (cf 15-20 sec in runtime for the two programs). There's bound to be some aggressive file caching going on, but I figure that would rather normalize program runtimes at lower times after running them a few times, but I see nothing indicating that. Two things that you could try: First hitlists.byKey can be expensive (especially if hitlists is big). Instead use: foreach( key, value ; hitlists ) Also the filter.array.length is quite expensive. You could use count instead. import std.algorithm : count; value.count!(h => h.pid >= (max_pid - max_pid_diff));
Re: Speeding up text file parser (BLAST tabular format)
On Monday, 14 September 2015 at 12:30:21 UTC, Fredrik Boulund wrote: Hi, Using a small test file (~550 MB) on my machine (2x Xeon(R) CPU E5-2670 with RAID6 SAS disks and 192GB of RAM), the D version runs in about 20 seconds and the Python version less than 16 seconds. I've repeated runs at least thrice when testing. This holds true even if the D version is compiled with -O. Sounds like this program is actually IO bound. In that case I would not expect a really expect an improvement by using D. What is the CPU usage like when you run this program? Also which dmd version are you using. I think there were some performance improvements for file reading in the latest version (2.068)
Re: Speeding up text file parser (BLAST tabular format)
On Monday, 14 September 2015 at 14:54:34 UTC, Fredrik Boulund wrote: On Monday, 14 September 2015 at 14:40:29 UTC, H. S. Teoh wrote: I agree with you on that. I used Python's cProfile module to find the performance bottleneck in the Python version I posted, and shaved off 8-10 seconds of runtime on an extraneous str.split() I had missed. I tried using the built-in profiler in DMD on the D program but to no avail. I couldn't really make any sense of the output other than that were enormous amounts of calls to lots of functions I couldn't find a way to remove from the code. Here's a paste of the trace output from the version I posted in the original post: http://dpaste.com/1AXPK9P See this link for clarification on what the columns/numbers in the profile file mean http://forum.dlang.org/post/f9gjmo$2gce$1...@digitalmars.com It is still difficult to parse though. I myself often use sysprof (only available on linux), which automatically ranks by time spent.
Re: What is "FilterResult" type?
On Tuesday, 8 September 2015 at 11:08:59 UTC, Bahman Movaqar
wrote:
On Tuesday, 8 September 2015 at 10:08:03 UTC, cym13 wrote:
Filter is a template and returns a FilterResult range which is
used to lazily compute the result. This behaviour is the same
for map and the majority of functions in std.algorithm.
You can also use .array to (greedily) evaluate the results, which
(for filter) will return a range of the same type as went in:
void main()
{
import std.array : array;
int[] arr = [1, 2, 3, 4, 5];
int[] result = arr.filter!(x => x%2).array;
}
Re: reading file byLine
On Friday, 4 September 2015 at 12:06:08 UTC, Edwin van Leeuwen
wrote:
On Friday, 4 September 2015 at 11:50:23 UTC, deed wrote:
import std.algorithm, std.range, std.array, std.string,
std.stdio,
std.conv;
int[] arr1 = [1, 2, 30];
//arr1.max.writeln; // Doesn't work, as you say
arr1.reduce!max.writeln;// This does. Prints 30.
Again using reduce is the functional way to do it. The above
basically boils down to:
int[] arr1 = [1, 2, 30];
int maxElement = arr1[1];
foreach( element; arr1[2..$] ) //2..$ is short hand for second
till last ($) element
{
maxElement = max( maxElement, element );
}
writeln( maxElement );
Sorry been using too much R, so my indexes are off by 1:
int[] arr1 = [1, 2, 30];
int maxElement = arr1[0];
foreach( element; arr1[1..$] ) //1..$ is short hand for second
till last ($) element
{
maxElement = max( maxElement, element );
}
writeln( maxElement );
Re: reading file byLine
On Friday, 4 September 2015 at 11:50:23 UTC, deed wrote:
import std.algorithm, std.range, std.array, std.string,
std.stdio,
std.conv;
int[] arr1 = [1, 2, 30];
//arr1.max.writeln; // Doesn't work, as you say
arr1.reduce!max.writeln;// This does. Prints 30.
Again using reduce is the functional way to do it. The above
basically boils down to:
int[] arr1 = [1, 2, 30];
int maxElement = arr1[1];
foreach( element; arr1[2..$] ) //2..$ is short hand for second
till last ($) element
{
maxElement = max( maxElement, element );
}
writeln( maxElement );
Re: (De)Serializing interfaces
On Monday, 24 August 2015 at 09:26:40 UTC, Edwin van Leeuwen wrote: On Saturday, 22 August 2015 at 19:14:16 UTC, nims wrote: Painlessjson indeed does not support interfaces/subclasses at the moment. There was some discussion about it here: https://github.com/BlackEdder/painlessjson/issues/8 , but we haven't really thought of a good way of doing it yet. Pull requests are welcome of course :)
Re: (De)Serializing interfaces
On Saturday, 22 August 2015 at 19:14:16 UTC, nims wrote: I think interfaces are very powerful and I heavily use them. The only problem I have with them is that serializing/deserializing them to XML or JSON doesn't seem to work. So far I got to try Orange and painlessjson. Using Orange all I got was a lot of compiler errors. Painlessjson did compile normally but just ignores all interface class members. Painlessjson indeed does not support interfaces/subclasses at the moment. There was some discussion about it here: https://github.com/BlackEdder/painlessjson/issues/8 , but we haven't really thought of a good way of doing it yet. There is also: http://code.dlang.org/packages/jsonizer which I think should support at least subclasses, not sure about intefaces.
Re: Compiletime Vs Runtime bencmarks
On Monday, 17 August 2015 at 14:43:35 UTC, D_Learner wrote: Hello everyone . I need advice on my first D-project . I have uploaded it at :- Current Results for the pattern=GCAGAGAG are as below :- BM_Runtime = 366 hnsecs position= 513 BM_Compile-time = 294 hnsecs position =513 BMH_Runtime = 174 hnsecs position= 513 BMH_Compile-time= 261 hnsecs position= 513 AG_Run-time = 258 hnsecsposition= 513 AG_Compile-time = 268 hnsecsposition= 513 Running the code : dmd -J. matcher.d inputs.d rtime_pre.d ctime_pre.d numactl --physcpubind=0 ./matcher Hi, What happens if you run each algorithm many (say 10) times. The current times seem to short to be reliable (variation in runtimes would be too great). Regards, Edwin
Re: dub and subpackages
On Friday, 14 August 2015 at 08:06:15 UTC, yawniek wrote: i'm trying to have my own versions of my dependencies as git submodules. whats the correct way of having a chain of packages included from git submodules so that every packages get's only picked once? dub add-local allows you to add local copy of a package. This will be system wide though, not only for the current package.
Re: Indivisual Incremental Compalation with dub
On Thursday, 13 August 2015 at 05:42:38 UTC, Freddy wrote: I have a file that takes a while to compile with a static interface. Is there any way i can make dub keep the object file of only that file(for faster compilation)? I don't think dub itself can do this, but https://github.com/atilaneves/reggae should be able to do it. And it will parse/understand your dub configuration file.
Using return type of a predicate function as a template
I am trying to implement a groupBy function that groups by the
return type of a predicate. Currently I have to define the
returntype of the predicate for it to compile. Is there a way to
get the return type at compile time and use it.
The code:
V[K] groupBy( alias func, K, V )( V values )
{
V[K] grouped;
foreach ( value ; values ) {
grouped[func( value )] ~= value;
}
return grouped;
}
unittest {
struct Test {
string a;
double b;
}
auto values = [Test( a, 1 ), Test( a, 2 ), Test( b, 3 )];
auto grouped = values.groupBy!( (a) = a.a, string );
assert( grouped[a].length == 2 );
assert( grouped[a][1].b == 2 );
assert( grouped[b].length == 1 );
assert( grouped[b][0].b == 3 );
}
So the above works, but I need to call it with:
values.groupBy!( (a) = a.a, string );
Ideally I would call it instead with:
values.groupBy!( (a) = a.a )
and it would infer that the template K needs to be a string,
since that is the return type of (a) = a.a.
Cheers,
Edwin
Re: Using return type of a predicate function as a template
On Thursday, 16 October 2014 at 08:18:02 UTC, Atila Neves wrote:
This works:
import std.range;
auto groupBy(alias func, R)(R values)
if (isInputRange!R)
{
alias K = typeof(func(values.front));
alias V = ElementType!R[];
V[K] grouped;
foreach(value; values) grouped[func(value)] ~= value;
return grouped;
}
Thank you, that is surprisingly straightforward :)
Edwin
Re: Recomended cairo bindings
On Monday, 15 September 2014 at 12:11:09 UTC, Paul Z. Barsan wrote: On Sunday, 14 September 2014 at 14:37:05 UTC, Robert burner Schadek wrote: If you look at deimos.cairo you will see that the latest commit was made 2 years ago while cairoD was last updated 6 months ago. I think the latest commit was made when I submitted a bug report. It seems that there is no ongoing development, but the maintainer/developer did react to my bug report very quickly, so it is/was still maintained at that time. I made my choice: I will stick to dub, fork cairoD, merge everything from deimos.cairo into cairoDs C-style bindings wrappers, update cairoDs dependencies to use dub pkgs and then provide and rdmd script to configure platform specific stuff. I have plenty of time and if I succed, everyone can benefit from my work. :) Out of curiosity: What does deimos.cairo add to cairoD? More higher level/d-like API? Cheers, Edwin
Re: DUB: link to local library
On Wednesday, 10 September 2014 at 13:40:16 UTC, rcor wrote:
dub.json contains what I think should do the same as above:
{
name: test,
importPaths: [ext/dallegro5],
lflags: [-Lext/dallegro5]
}
Does adding:
libs: [dallegro5]
make a difference?
Cheers, Edwin
Re: D JSON (WAT?!)
On Thursday, 24 July 2014 at 15:42:58 UTC, Pavel wrote:
On Thursday, 24 July 2014 at 15:38:06 UTC, John Colvin wrote:
On Thursday, 24 July 2014 at 15:32:29 UTC, John Colvin wrote:
On Thursday, 24 July 2014 at 15:15:37 UTC, Pavel wrote:
Ok, let me start with the sample code:
import std.stdio;
import std.json;
void main() {
scope(failure) writeln(FaILED!!);
string jsonStr = `{ name: 1, type: r }`;
auto parsed = parseJSON(jsonStr);
string s = parsed[fail].str;
writeln(s == );
writeln(s is null);
writeln(s);
}
Running rdmd app.d doesn't produce any output.
Can anyone explain such a behavior???
PS: Running dmd v2.065 on Linux x64.
It's a bug in std.json (you should get a segfault, not no
output at all)
It is fixed now and I'm pretty sure it will be in 2.066
std.json has been improved a lot, but I would still recommend
using http://vibed.org/api/vibe.data.json/ instead
perhaps bug is too strong a word, but it was a deficiency
that is now corrected. You will get an exception thrown now
and everything should work how you expect.
Maybe. But still it's not the way I expect, any time you check
for non-existing property you must consider exception, which is
very heavy to deal with in such a situation. I'd rather expect
to get null, whenever I try to fetch non-existing property, and
not an exception.
You can turn your json object into an AA object and then use in
to check for existence (I know it is not very intuitive):
JSONValue[string] jsonAA = parsed.object;
if ( fail in jsonAA )
s = jsonAA[fail].str;
That's purely my point, and I don't claim to be right in this
way. It's up to Phobos maintainers to decide how to reprent
JSON parsing results.
Re: Delegate, scope and associative array
On Tuesday, 3 June 2014 at 05:40:44 UTC, Edwin van Leeuwen wrote:
On Monday, 2 June 2014 at 23:44:01 UTC, Rene Zwanenburg wrote:
On Monday, 2 June 2014 at 20:09:12 UTC, Edwin van Leeuwen
wrote:
As you may have guessed, a workaround is to copy the iteration
variable yourself:
unittest {
size_t delegate()[size_t] events;
foreach(_i; 1..4 ) {
auto i = _i;
events[i] = { return i; };
}
assert( events[1]() == 1 );
}
This should work though it's less than ideal. There is an open
bug report:
https://issues.dlang.org/show_bug.cgi?id=8621
Thanks for the suggestion and I just tried it, but it does not
work :(
In the original code were I discovered this problem I generated
the id with an outside function and that also didn't to work.
unittest {
size_t delegate()[size_t] events;
size_t i = 1;
events[i] = { return i; };
i = 2;
events[i] = { return i; };
i = 3;
events[i] = { return i; };
writeln( events[1]() );
assert( events[1]() == 1 );
}
Explicitly removing the loop still causes the same issue. In that
case I find it easier to understand, since it might be using the
value of i at the end of the scope. In the foreach case (and
especially when copying to a local variable) it is more puzzling
to me.
Re: Delegate, scope and associative array
On Tuesday, 3 June 2014 at 07:00:35 UTC, Ali Çehreli wrote:
Here is a workaround:
unittest {
size_t delegate()[size_t] events;
auto makeClosure(size_t i) {
return { return i; };
}
foreach( i; 1..4 ) {
events[i] = makeClosure(i);
}
assert( events[1]() == 1 );
}
void main()
{}
Ali
Thank you Ali, that works beautifully and can be easily adapted
to the original (more complicated) case.
Cheers, Edwin
Delegate, scope and associative array
I'm probably missing something basic, but I am confused by what
is going on in the following code.
unittest {
size_t delegate()[size_t] events;
foreach( i; 1..4 ) {
events[i] = { return i; };
}
writeln( events[1]() ); // This outputs 3
assert( events[1]() == 1 );
}
I thought that i should be copied from the local scope and
therefore when I call events[1]() the return value should be 1,
but in this case it is 3 (it always seems to be the last value of
i in the loop).
Cheers, Edwin
Re: Delegate, scope and associative array
On Monday, 2 June 2014 at 23:44:01 UTC, Rene Zwanenburg wrote:
On Monday, 2 June 2014 at 20:09:12 UTC, Edwin van Leeuwen wrote:
As you may have guessed, a workaround is to copy the iteration
variable yourself:
unittest {
size_t delegate()[size_t] events;
foreach(_i; 1..4 ) {
auto i = _i;
events[i] = { return i; };
}
assert( events[1]() == 1 );
}
This should work though it's less than ideal. There is an open
bug report:
https://issues.dlang.org/show_bug.cgi?id=8621
Thanks for the suggestion and I just tried it, but it does not
work :(
In the original code were I discovered this problem I generated
the id with an outside function and that also didn't to work.
