On Wednesday, 12 September 2018 at 15:12:16 UTC, Anonymouse wrote:
void doByPair(Args...)(Args args)
if (Args.length)
{
foreach (pair; args.pairwise)
{
static assert(is(typeof(pair[0]) == string));
static assert(isPointer!(pair[1]));
assert(pair[1] !is null);
On Monday, 3 September 2018 at 22:07:10 UTC, aliak wrote:
Why does it work with nogc but not with pure?
Cheers,
- Ali
You can't define an impure function inside a pure unittest. If
you move `modify` outside the unittest block, and change the
argument from a lambda to a function pointer, it
On Monday, 3 September 2018 at 09:09:44 UTC, Andrey wrote:
Hello,
Here is a code with comments: https://run.dlang.io/is/BNl2Up.
I don't understand how to pass lambda into template.
I get an error:
onlineapp.d(18): Error: template instance `qwerty!((i) => "arg"
~ i.to!string ~ "[0] == '?'",
On Wednesday, 29 August 2018 at 22:18:09 UTC, Everlast wrote:
No it is not! you have simply accepted it to be fact, which
doesn't make it consistent.
If you take 100 non-programmers(say, mathematicians) and ask
them what is the natural extension of allowing an arbitrary
number of parameters
On Wednesday, 29 August 2018 at 19:56:31 UTC, Everlast wrote:
One of the things that makes a good language is it's internal
syntactic consistency. This makes learning a language easier
and also makes remembering it easier. Determinism is a very
useful tool as is abstraction consistency. To say
On Tuesday, 28 August 2018 at 20:37:05 UTC, Everlast wrote:
Also, the biggest complaint is that when we use [] attached to
a type it has a specific meaning as "an array of". e.g., int[]
means an array of int's.
But int[] a... then changes as we don't have an array of int's
any more but
On Tuesday, 28 August 2018 at 19:09:38 UTC, Everlast wrote:
Yeah, I see the link paul posted. The actual syntax seems a bit
strange to me...
We don't do
A[] a
So it is not "logical".
foo(A...)(A a)
but if A is a specific type we must do
foo(int[] a ...)
The actual syntax then looks
On Monday, 27 August 2018 at 09:50:01 UTC, Andrey wrote:
alias Pair(alias key, alias value) = AliasSeq!(key, value);
alias Pairs = AliasSeq!(Pair!(Option.First,
handler!(Option.First)), Pair!(Option.Second,
handler!(Option.Second)), handler);
You can't nest AliasSeqs. If you examine Pairs
On Sunday, 26 August 2018 at 06:08:39 UTC, vit wrote:
const x = iota(0, 10)
.map!((x, i) => x*i)(a) ///map!((x) => x*a)
.map!((x, i) => x*i)(b) ///map!((x) => x*b)
.filter!((x, i) => x%i)(c)///filter!((x) => x%c)
.any!(x => x % c);
I think it's easier to
On Sunday, 26 August 2018 at 02:26:58 UTC, Everlast wrote:
The problem is, suppose one wants to specify A
void print(T, int... A)(T t, A a)
while tricks can be used, why doesn't D support such an obvious
syntax? We can specify an arbitrary type but can't restrict it
in an obvious way, in
On Friday, 24 August 2018 at 15:18:13 UTC, Peter Alexander wrote:
I can write scaleAll like this:
auto scaleAll(int[] xs, int m) @nogc {
return repeat(m).zip(xs).map!(mx => mx[0] * mx[1]);
}
So that repeat(m) stores m, but it is quite hacky to work like
this.
Here's a spoonful of sugar to
On Monday, 20 August 2018 at 13:14:14 UTC, Andrey wrote:
Hello,
I want to make an alias to function "std.stdio.writeln" and
"std.stdio.write" and use it like:
static void log(bool newline = true)(string text)
{
alias print(T...) = newline ? :
_file.print();
text.print();
}
On Monday, 20 August 2018 at 12:33:34 UTC, Andrey wrote:
On Monday, 20 August 2018 at 11:38:39 UTC, Paul Backus wrote:
Create an overload of foo that takes two arguments and
combines them into a `Data` struct internally:
void foo(int a, string text)
{
Data data = {a, text};
foo(data);
On Monday, 20 August 2018 at 09:23:27 UTC, Andrey wrote:
Hello,
I have a function and a struct:
void foo(ref Data data) { ... }
struct Data
{
int a;
string text;
}
How to pass struct into function without naming its type?
This doesn't work:
foo({1234, "Hello!"});
Create an
On Monday, 20 August 2018 at 00:27:04 UTC, Nick Sabalausky
(Abscissa) wrote:
Suppose I've wrapped a Variant in a struct/class which ensures
the Variant *only* ever contains types which satisfy a
particular constraint (for example: isInputRange, or hasLength,
etc...).
Is there a way to call a
On Wednesday, 15 August 2018 at 13:53:02 UTC, Andrey wrote:
Hello,
I have the following code:
string[] list;
string text;
// ...
enum pattern = ctRegex!`^[0-9]+$`;
list = text.split('\n').map!(line =>
line.matchFirst(pattern).hit);
Compiler says that it can't convert result of map function
On Tuesday, 14 August 2018 at 13:01:57 UTC, learnfirst1 wrote:
enum string[] a = ["a"];
extern(C) void main() {
int i = 0;
auto s = a[i];
}
---
Error: TypeInfo cannot be used with -betterC
Workaround: https://run.dlang.io/is/NZykl0
Source:
On Sunday, 12 August 2018 at 02:17:21 UTC, Cecil Ward wrote:
I was thinking about reflection and powerful things like
traits. Would a test to see if a static if compile do the trick
? You ask the question using traits : "does the following
compile? : { static if ( mask == 3 ) { }; }" - any
On Sunday, 12 August 2018 at 00:15:37 UTC, Cecil Ward wrote:
Paul, what would the calls look like?
I am about to misunderstand things completely so here goes :-)
It would be a bit kludgy having to switch from one calling
syntax to another, putting the mask argument in the template
parameters
On Saturday, 11 August 2018 at 05:17:51 UTC, Cecil Ward wrote:
T myfunc(T)( T x, uint mask )
if ( mask == 3 )
{
return fast_func( x, mask );
}
but of course this doesn't work because mask is not known at
compile-time. so I wondered if there is a way to do something
like static if
On Friday, 10 August 2018 at 11:10:55 UTC, learnfirst1 wrote:
Still, if my first example is use GC, why dmd not throw error
at compile time, instead at link time report symbols is
missing. Is this a bug ?
If you make your main function @nogc, you will get a compile-time
error.
On Friday, 10 August 2018 at 09:57:53 UTC, learnfirst1 wrote:
import core.stdc.stdio;
struct Test {
string name ;
}
void T(alias pred, A...)(){
__gshared t = Test(A) ;
pred(t);
}
extern(C) void main(){
T!(t => printf("test 1 name = %s\n".ptr, t.name.ptr), "test")
;
On Wednesday, 8 August 2018 at 17:08:57 UTC, vit wrote:
Hello, is in phobos some function which convert float/double to
string and is pure @nogc and nothrow?
Short answer: no.
Long answer: https://issues.dlang.org/show_bug.cgi?id=17628
On Monday, 6 August 2018 at 20:22:36 UTC, vit wrote:
On Monday, 6 August 2018 at 19:56:03 UTC, Steven Schveighoffer
wrote:
BTW, is there a reason you aren't just using Algebraic?
https://dlang.org/phobos/std_variant.html#.Algebraic
-Steve
primarily visit for Algebraic isn't pure, @nogc,
On Sunday, 5 August 2018 at 12:23:17 UTC, vit wrote:
Yes, it isn't possible.
I modify filter a and map from std.algorithm:
void main()@nogc{
import std.experimental.all;
const int j = 2;
int i = 0;
const int[3] tmp = [1, 2, 3];
tmp[]
On Wednesday, 11 July 2018 at 08:31:30 UTC, Dorian Haglund wrote:
But it fails to compile (with gdc 8.1.0, dmd v2.081)
complaining that
template instance reduce!(f) cannot use local 'f' as parameter
to non-global template reduce(functions...)
Congratulations! You've just run into issue
On Sunday, 3 June 2018 at 15:07:07 UTC, DigitalDesigns wrote:
I'm calling pipe process using
pipeProcess([AliasSeq!args], Redirect.stdout | Redirect.stdin);
where args is a tuple.
Everything works when I pass each argument individually. If I
combine any args using a space it fails or if I
On Monday, 4 September 2017 at 03:26:23 UTC, EntangledQuanta
wrote:
Take a variant type. It contains the "type" and the data. To
simplify, we will treat look at it like
(pseudo-code, use your brain)
enum Type { int, float }
foo(void* Data, Type type);
The normal way to deal with this is a
On Thursday, 31 May 2018 at 19:26:12 UTC, Dr.No wrote:
My application create some HTML which is then converted to PDF
by wkhtmltopdf library. I'm trying to figure out how make the
PDF generation run parallel, currently, it's running linearly.
It looks like wkhtmltopdf does not support
On Thursday, 17 May 2018 at 15:25:37 UTC, Sjoerd Nijboer wrote:
I want to make a template mixin that is able to cast one of
these generic structs to the other explicitly. I have a bunch
of these structs and therefore I thought it would make sense to
do it by template mixin. I just don't know
On Thursday, 12 April 2018 at 20:34:40 UTC, Chris Katko wrote:
But each doesn't return anything, it mutates, right? I think
that's the problem I ran into with my attempt. With your code,
I get an error about void:
string []x = split(file.readln.idup, " ");
x.each((ref s) => s.each((ref
On Tuesday, 10 April 2018 at 12:34:07 UTC, aliak wrote:
Awesome!
this is a neat trick:
union
{
AliasSeq!(T0, T1) values;
}
Is that usage documented somewhere, or is it somewhere in
phobos maybe?
Also, can Algebraic be fully replaced with this version then or
is there some functionality
On Tuesday, 10 April 2018 at 00:22:18 UTC, helxi wrote:
On Monday, 9 April 2018 at 15:59:32 UTC, Paul Backus wrote:
On Monday, 9 April 2018 at 07:07:58 UTC, Chris Katko wrote:
[...]
I agree in general, but in this case it's actually completely
doable. In fact, I've done it myself: check out
On Monday, 9 April 2018 at 07:07:58 UTC, Chris Katko wrote:
On Monday, 9 April 2018 at 07:02:50 UTC, Hasen Judy wrote:
IMO, this is one more reason why sum-types should be built
into the language compiler, instead of being implemented in
user-space.
+1. Any time you have to "create" a
On Sunday, 8 April 2018 at 15:04:49 UTC, number wrote:
the write() shows a 'null' if the struct has a function/method.
why is that?
```
import std.stdio;
void main()
{
struct S
{
int i;
}
S s;
writeln(s);// S(0)
On Saturday, 7 April 2018 at 14:02:55 UTC, Paul Backus wrote:
Interesting. Looks like this is an issue with aliases, because
I get the error with this code too:
--- test.d
import std.typecons: Tuple, tuple;
alias Pair(T) = Tuple!(T, T);
void foo(T)(Pair!T p)
{
return;
}
unittest {
On Saturday, 7 April 2018 at 06:26:24 UTC, Uknown wrote:
What I did notice though is that when
`string list2string(T)(List!T list)` was changed to
`string list2string(T)(VariantN!(16LU, Nil, Tuple!(T, "head",
This*, "tail")) list)`
The compiler correctly deduce `T` to be `int`
Interesting.
On Saturday, 7 April 2018 at 05:46:07 UTC, Uknown wrote:
I don't see the error you are talking about:
https://run.dlang.io/is/XWPIc1
Are you using the latest compiler?
Compile with -unittest.
And yes; I'm using DMD 2.079.0.
I'm playing around with functional programming in D, and have run
into a problem with the following code:
--- list.d
import std.variant: Algebraic, This, visit;
import std.typecons: Tuple, tuple;
struct Nil {}
alias List(T) = Algebraic!(
Nil,
Tuple!(T, "head", This*, "tail")
);
alias
On Wednesday, 21 March 2018 at 16:22:45 UTC, Martin Tschierschke
wrote:
Is there an step by step introduction how to convert a C header
of an external lib into the right extern(C){} block?
In addition to what others have said, I found the following
article on the D Wiki useful:
On Sunday, 25 February 2018 at 16:22:19 UTC, ARaspiK wrote:
Instead of passing std.range.zip a set of ranges as different
arguments, is it possible to hand the m a range of ranges, and
get them to zip together each element of every subrange?
`std.range.transposed` does this, but it requires
On Wednesday, 7 February 2018 at 19:25:01 UTC, aliak wrote:
import std.range: iota;
0.iota.front(100).writeln;
// Error: inout method std.range.iota!(int,
int).iota.Result.front is not callable using a mutable object
import std.algorithm: filter;
auto arr = [0, 1];
On Saturday, 6 January 2018 at 03:38:35 UTC, codephantom wrote:
or even..
a.append( s.to!ConvertToElementType(a) );
That's not valid code of course, but the semantics are all
contained in that single chunk.
This works:
import std.range.primitives: ElementType;
a ~=
On Thursday, 4 January 2018 at 17:45:35 UTC, Stijn wrote:
Why is it not allowed for a variable name to match a type name?
The following example fails with "Error: variable foo conflicts
with struct foo"
struct foo {}
foo foo;
Imagine if you then tried to write something like
On Monday, 20 February 2017 at 16:04:17 UTC, Martin Tschierschke
wrote:
Hello,
I have a little program where I am filling a struct with values
from an regex match.
Now I want to display the content of the struct for debugging
purpose.
I believe the easiest way to do this is to define a
On Wednesday, 16 November 2016 at 02:24:26 UTC, azzuwan wrote:
It seems that /usr/bin/dman is currently used by
deepin-manual. Is there anyway to get around this?
Take a look at dpkg-divert(1)
On Friday, 4 November 2016 at 23:38:47 UTC, sarn wrote:
I suggest trying it with the latest dmd and filing a bug
report. Taking a quick look at the library code
(https://github.com/dlang/phobos/blob/master/std/variant.d), it
*seems* like everything uses templates and functions returning
On Friday, 4 November 2016 at 02:28:17 UTC, bluphantom91 wrote:
Hello,
I am trying to finish up a group project but I am running into
a small problem. I keep getting an error about fgetc not being
callable. The purpose of my program is to count the number of
characters in a file. Any bit of
As a learning exercise, I'm writing a simple AST evaluator for
arithmetic expressions in D. (See
https://gist.github.com/ckirkendall/2934374) In order to get a
feel for functional programming in D, I decided to try and
implement my solution in a functional style, using algebraic data
types
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