Re: The One Billion Row Challenge
On Thursday, 11 January 2024 at 08:57:43 UTC, Christian Köstlin wrote: Did someone already try to do this in dlang? I guess it will be very hard to beat the java solutions running with graalvm! https://news.ycombinator.com/item?id=38851337 Kind regards, Christian I think C++ people already beated Java's performance https://github.com/buybackoff/1brc?tab=readme-ov-file#native
Re: Generating custom toString for structs
On Sunday, 7 January 2024 at 09:49:36 UTC, Renato wrote:
Hi, I wanted to customize the toString implementation for my
structs.
So I wrote a mixin for doing that:
Alternative format similar to what you already have:
```d
import std.format;
mixin template ToStringMixin() {
void toString(W)(ref W writer) {
alias T = typeof(this);
writer.formattedWrite("%s(\n", T.stringof); // See also:
std.traits.fullyQualifiedName
static foreach (idx, field; T.tupleof) {
writer.formattedWrite("\t%s: %s\n", T.tupleof[idx].stringof,
this.tupleof[idx]);
}
put(writer, ")");
}
}
struct Foo {
int x, y;
string s;
mixin ToStringMixin;
}
void main() {
auto foo = Foo(3, 4, "hello");
writeln(foo);
}
```
Note however that the templated version of toString(W) can be
difficult to debug in some cases as, if it fails to compile,
std.format will simply ignore it and not use it while the rest of
the program compiles successfully. Any compilation error message
can be seen by instead attempting to call the method directly,
e.g. something like `auto a = appender!string; foo.toString(a);`.
I don't use the delegate version personally, but if that's
already working for you, may as well stick with it.
If you wanted to avoid including a mixin in all of your structs,
another option is to create a generic templated container struct
with its own toString:
```d
struct ToStringer(T) {
T t; // Consider T* t
void toString(W)(ref W writer) {
//assert(t !is null);
writer.formattedWrite("%s(\n", T.stringof);
static foreach (idx, field; T.tupleof) {
writer.formattedWrite("\t%s: %s\n", T.tupleof[idx].stringof,
t.tupleof[idx]);
}
put(writer, ")");
}
}
auto ToString(T)(ref T t) { // syntactic sugar
return ToStringer!T(t);
}
struct Foo {
int x, y;
string s;
}
void main() {
auto foo = Foo(3, 4, "hello");
//writeln(ToStringer!Foo(foo));
writeln(foo.ToString);
}
```
Re: The One Billion Row Challenge
On Thursday, 11 January 2024 at 08:57:43 UTC, Christian Köstlin wrote: Did someone already try to do this in dlang? I guess it will be very hard to beat the java solutions running with graalvm! https://news.ycombinator.com/item?id=38851337 Kind regards, Christian The problem with this challenge can be seen in the initial comments. Writing the fastest possible program *for a specific dataset* is not the same thing as writing the fastest program for an arbitrary dataset of that size. And, indeed, the fastest program is the one that does nothing but print the answer. Speed on this task doesn't tell you anything about performance with different types/sizes of data or constraints on programmer time needed to produce a correct implementation and maintain it over time.
Re: How to use ImportC to import WebGPU header
On Wednesday, 10 January 2024 at 23:36:33 UTC, JN wrote: I would like to use ImportC to automatically import a C header into my D project. It was already done. Use it https://code.dlang.org/packages/wgpu-d Don't reinvent the wheel :)
Re: Generating custom toString for structs
On Thursday, 11 January 2024 at 12:45:45 UTC, cc wrote: I don't use the delegate version personally, but if that's already working for you, may as well stick with it. In retrospect, that delegate version is probably quite a bit better.
Re: How to use ImportC to import WebGPU header
You need to use a .c file that include it
--- webgpu.c
```c
#include "webgpu.h"
```
--- app.d
```d
import std.stdio;
import webgpu;
void main()
{
writeln(WGPUBlendFactor_Dst);
}
```
result:
```
$ dmd -run app.d webgpu.c
WGPUBlendFactor_Dst
```
