Improper display of Cyrillic in `pragma (msg, ...)` on Windows
Hi,
To view Cyrillic CMD on Windows can be used
`std.process.executeShell("chcp 65001 ");` and it works.
What should I use to change the encoding to UTF-8 to the compiler
messages in `pragma(msg, ...)` on Visual D?
//
import std.stdio, std.process;
void main() {
executeShell("chcp 65001");
writeln("Привет, мир!"); // Привет, мир! -> OK
pragma(msg, "Привет, мир!"); // Привет, РјРёСЂ! -> wrong
}
//
PS C++ supports the following directive in Visual Studio:
https://msdn.microsoft.com/en-us/library/mt708823.aspx
Re: to auto or not to auto ( in foreach )
On Saturday, 16 July 2016 at 14:00:56 UTC, dom wrote: foreach(auto v; msg) writeln(v); gives an error that a basic type is expected foreach(v; msg) writeln(v); works .. but why? `Note: The ForeachTypeAttribute is implicit, and when a type is not specified, it is inferred. In that case, auto is implied, and it is not necessary (and actually forbidden) to use it.` http://dlang.org/spec/statement.html#ForeachStatement
Re: fast way to insert element at index 0
On Tuesday, 23 June 2015 at 05:16:23 UTC, Assembly wrote:
What's a fast way to insert an element at index 0 of array? now
that the code is working I want to clean this:
void push(T val)
{
T[] t = new T[buffer.length + 1];
t[0] = val;
t[1 .. $] = buffer;
buffer = t;
}
I did this because I didn't find any suble built-in data
structure that let me insert an item into a specific index at
first search. Slist does have insertFron(), exactly what I'm
looking for it's a linked list.
I think you want to do something like this:
void main() {
import std.algorithm;
auto a = [1, 2, 3];
int val = 5;
a = val ~ a; // vector.pushFront();
assert(equal(a[], [5, 1, 2, 3]));
}
Re: Higher Order Range Pattern
On Monday, 22 June 2015 at 15:25:12 UTC, Steven Schveighoffer wrote: On 6/22/15 11:04 AM, Dennis Ritchie wrote: Hi, I recently came across the following code: http://wiki.dlang.org/Higher_Order_Range_Pattern I can't understand why the properties and methods of the structure are called in the correct order. Why are the property `back()` and the method `popBack()` are not called even once? Because std.algorithm.equal does not use back or popBack. In general, please explain how it all works. I have a feeling you are not understanding something. This code is pretty straightforward, I don't know what else to explain about it. -Steve Thanks. I understand everything, just std.algorithm.equal introduced me to the great confusion :) Now everything fell into place.
Higher Order Range Pattern
Hi,
I recently came across the following code:
http://wiki.dlang.org/Higher_Order_Range_Pattern
I can't understand why the properties and methods of the
structure are called in the correct order.
Why are the property `back()` and the method `popBack()` are not
called even once?
In general, please explain how it all works.
```
import std.stdio, std.range;
struct Retro(Range)
{
@property
{
auto ref front() { debug writeln("back"); return
range_.back; }
auto ref back() { debug writeln("front"); return
range_.front; }
bool empty() { debug writeln("empty"); return
range_.empty; }
}
void popFront() { debug writeln("popBack"); range_.popBack();
}
void popBack() { debug writeln("popFront");
range_.popFront(); }
Range range_;
}
auto retro(Range)(Range range)
{
return Retro!Range(range);
}
void main()
{
import std.algorithm;
auto arr = [1, 2, 3, 4, 5];
assert(equal(retro(arr), [5, 4, 3, 2, 1]));
}
```
http://rextester.com/FMPGS76502
Re: How to avoid multiple spelling `import`
On Tuesday, 16 June 2015 at 12:41:14 UTC, Daniel Kozák wrote:
On Tue, 16 Jun 2015 11:45:22 +
Dennis Ritchie via Digitalmars-d-learn
wrote:
I just want to import individual features of these modules.
mixin template include(w...)
{
mixin _include!(w.length - 1, w);
}
mixin template _include(long N, i...)
{
mixin("import " ~ i[N] ~ ";");
mixin _include!(N - 1, i);
}
mixin template _include(long N : 0, i...)
{
mixin("import " ~ i[N] ~ ";");
}
mixin include!(
"std.stdio : writeln, write",
"std.conv : to"
);
void main() {
writeln(to!string(7));
}
Thanks. Maybe I'll use this code in your own programs.
I still believe that this design deserves existence in D:
https://issues.dlang.org/show_bug.cgi?id=14704
Re: How to avoid multiple spelling `import`
Maybe not everyone needs these features. But, unfortunately, I
often use a lot of imported modules. And use every time the word
`import` very bad.
version (none) {
import std.math,
std.conv,
std.stdio,
std.ascii,
std.range,
std.array,
std.regex,
std.format,
std.bigint,
std.traits,
std.random,
std.string,
std.numeric,
std.variant,
std.typecons,
std.container,
std.algorithm,
std.typetuple,
std.exception,
core.checkedint;
}
I just want to import individual features of these modules.
Re: How to avoid multiple spelling `import`
On Tuesday, 16 June 2015 at 11:16:32 UTC, Idan Arye wrote: There is no problem to be solved here. Having to type `import` for each imported module is not big enough a burden to justify this additional syntax. No, I think it is a holdover from C++-times — to write `import` for each new header file. For example, this feature is implemented Go: import ( "os" "bufio" "strings" "fmt" )
How to avoid multiple spelling `import`
Hi,
I can write this:
import std.range : chain, split;
But I can not write this:
import std.range : chain, split, std.algorithm : map, each;
We have several times to write the word `import`:
import std.range : chain, split;
import std.algorithm : map, each;
Does D something to solve this problem? Maybe there is something
like:
import std.range{chain, split}, std.algorithm{map, each};
import std.range(chain, split), std.algorithm(map, each);
import {
std.range : chain, split;
std.algorithm : map, each;
}
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 18:15:30 UTC, Dennis Ritchie wrote: Actually, I will file issue `std.conv` in Phobos to add such specifications. It will suit me. *specializations
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 17:39:25 UTC, Kagamin wrote: Type is probably possible, though conversion method will be simpler. You can even try to write a specialization of `to` for multidimentional arrays if it doesn't work. It appears the problem can be solved by creating specifications .to!strArray, which will determine the dimension of the array and convert it to char[][][][]... Actually, I will file issue `std.conv` in Phobos to add such specifications. It will suit me. Thanks to all. I just didn't know that such a conversion is running.
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 17:37:31 UTC, anonymous wrote: Please show how it is not. Seems to work just fine. OK. Still, this method works: char[][][][][][] strArr = ["foo", "baz"], ["bar", "tor".to!(char[][][][][])]; But I don't want to write this `.to!(char[][][][][])`. On Saturday, 13 June 2015 at 17:37:31 UTC, anonymous wrote: Your definitions of "something like that" and "other ways" are unreasonably narrow, in my opinion. Typing out ".dup" is D's way to do mutable strings. You just don't like it. Yes, I don't like it.
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 16:20:46 UTC, anonymous wrote: Do you like to write? char[][] strArray = ["foo".dup, "bar".dup, "baz".dup]; Ok. That's all you're on about? Basically you'd like this: char[] s = "foo"; and this: char[][] a = [["foo"]]; etc. Yes. That's right, and not otherwise :) Yeah, that would be neat. But typing out ".dup" isn't that bad, and converting a `string[]` to a `char[][]` is simple: import std.conv: to; auto a = ["foo"].to!(char[][]); Yes, but it is not suitable for multidimensional array of strings. I suggest that such an option: str[] strArray = ["foo", "bar", "baz"]; I don't see how adding a new builtin type `str` would solve anything. And why in C++ is running `std::vector` ? Really in D can not do something like that? Maybe a new type will not solve anything, but there should be other ways to do in D analogue strings of C++. On Saturday, 13 June 2015 at 16:22:44 UTC, anonymous wrote: I don't understand what you're trying to say with that quote. I would not say `simpler`, and `basic`. I just forgot the right word, because my English is not good enough.
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 15:45:34 UTC, anonymous wrote: Huh? You mean with string literals? That would be a rather silly reason to avoid `char[]`. Please show an example of .dup you'd like to avoid. Yes, string literals. I understand that the type of `string[]` to D is a simple data type than `char[][]`, Are you saying that `string[]` is simpler than `char[][]`? That's not true: `string` is an alias for `immutable(char)[]`, so `string[]` is the same as `immutable(char)[][]`. On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: But really, a string is immutable. There's not a way around that. A string is the most basic level of array primitive, not even mutable arrays of non-char types have that, and it's an annoyance. From there, you have to build the data out of ROM into the heap. http://forum.dlang.org/post/mjctql$j19$1...@digitalmars.com
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 15:45:34 UTC, anonymous wrote: Please show an example of .dup you'd like to avoid. For example, if you need to create a five-dimensional array of strings :)
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 15:45:34 UTC, anonymous wrote: Before jumping to a solution, please elaborate on the perceived problem. I have a feeling that there is none. Do you like to write? char[][] strArray = ["foo".dup, "bar".dup, "baz".dup]; I suggest that such an option: str[] strArray = ["foo", "bar", "baz"]; On Saturday, 13 June 2015 at 15:38:31 UTC, Dennis Ritchie wrote: Ie str, wstr, dstr be mutable counterparts immutable strings respectively str (mutable(char[])), wstr (mutable(wchar[])), dstr (mutable(dchar[])). In C++: std::vector std::string in C++. str[], wstr[], dstr[] in C++: std::vector > std::vector in C++.
Re: char[][] to std::vector - DIP or dmd-issue?
On Saturday, 13 June 2015 at 15:21:19 UTC, Dennis Ritchie wrote: I wish to propose the creation of new types of data D: str, wstr, dstr, which will be the analogs of C++ `std::vector`. Ie str, wstr, dstr be mutable counterparts immutable strings respectively str (mutable(char[])), wstr (mutable(wchar[])), dstr (mutable(dchar[])). In C++: std::vector str[], wstr[], dstr[] in C++: std::vector >
char[][] to std::vector - DIP or dmd-issue?
Hello, everyone! I like to work with arrays of strings like `string[] strArray`, but unfortunately, they are immutable. I do not like to work with arrays of strings such as `char[][] strArray`, because it is necessary to apply the method .dup each substring to make them work :) I understand that the type of `string[]` to D is a simple data type than `char[][]`, but it seems to me that the problem is solved in C++: std::vector stdArray; I wish to propose the creation of new types of data D: str, wstr, dstr, which will be the analogs of C++ `std::vector`. I do not know whether it is possible to create in the D, but I want to know where I write a sentence? Can I file a dmd-issue, or should I create a DIP, because it is too big improvement?
Re: appender!(dchar[]) put fail
On Saturday, 13 June 2015 at 13:32:19 UTC, kerdemdemir wrote: One more question I am asking those kind of questions to understand and not ask same stuff over and over, : auto totalStr = chain(stringB.replicate(bCount), stringC.replicate(cCount)); writeln(typeof(totalStr.array()).stringof); >dchar[] But auto totalStr = chain(stringB.repeat(bCount), stringC.repeat(cCount)); writeln(typeof(totalStr.array()).stringof); >dchar[][] It seems to me a little inconsistent. range.repeat and array.replicate gives result in difference dimension. Is there any explanation or logic that I am missing which results this behaviour? std.range.repeat is a lazy version unlike std.array.replicate: 5.repeat(3).writeln; // a lazy version // [5, 5, 5] [5].replicate(3).writeln; // [5, 5, 5] // but [5].repeat(3).writeln; // a lazy version // [[5], [5], [5]]
Re: appender!(dchar[]) put fail
On Saturday, 13 June 2015 at 13:01:29 UTC, kerdemdemir wrote:
Sorry to making the discussion longer and wasting your times.
But I am looking for a way without for loops. Also looping
every element one by one does not seems very efficient to me.
Any advices for that?
Maybe it fit?
auto stringB = readln.chomp.map!(to!dchar).array;
auto stringC = readln.chomp.map!(to!dchar).array;
auto charAppender = appender!(dchar[][]);
auto totalStr = stringB.repeat(3).chain(stringC.repeat(5));
charAppender.put(totalStr);
writeln(charAppender);
charAppender.put("c"d.dup);
charAppender.put("test"d.dup);
writeln(charAppender);
Re: Json
On Friday, 12 June 2015 at 00:35:35 UTC, Cassio Butrico wrote: Thank you for answering me so fast , where do I get the DUB for windows ? http://code.dlang.org/download
Re: Json
On Thursday, 11 June 2015 at 23:58:33 UTC, Cassio Butrico wrote:
What does the .json file and how to use it?
In D a file with the extension *.json is used to describe packets
that are included in your project, the dependency manager DUB.
For example, you can install Eclipse with DDT and create a
project with DUB. The file dub.json write the following:
-
{
"name" : "myDupApp",
"description" : "Carbon - Test.",
"dependencies" : {
"carbon": "~>1.4.1"
}
}
-
Save the file (Ctrl + S). Then in your project with DUB
downloaded package `carbon`:
http://code.dlang.org/packages/carbon
After that you can safely use the package `carbon`:
-
import std.stdio, carbon.linear;;
void main() {
auto m = matrix!(2, 3, (i, j) => i * 3 + j);
writeln(m); // [[0, 1, 2], [3, 4, 5]]
}
Re: Reading array of integers readln performance issues
On Thursday, 11 June 2015 at 19:56:00 UTC, kerdemdemir wrote:
Hi;
To learn D better and challanging myself I am tring code
computation's with D.
There is a question which is about reading a line of integer
which consist of 20 elements.
My solution fails because "Time limit exceeded", I thought it
is because of my algorithm first. I realize time limit is
exceeded even before my algorithm starts while reading line of
integers. I understand this by giving a wrong answer to
question after readln statement. I did that to get a "wrong
answer error" but my code still get a "Time limit exceed" error
because "readln" takes very long time.
Can I achieve something faster than code below?
auto peopleMoney = stdin.readln().split().map!(a =>
to!int(a)).array();
if (peopleMoney.length == 20)
writeln(":(");
Regards
Erdem
Ps: I do not want to bore you with long code, but I am sending
link to whole program anyway if anyone need.
http://codeforces.com/contest/549/submission/11537206
Your algorithm works for about quadratic time. For N = 20
your algorithm will work terribly long. The function `readln()`
nothing to do with:
http://codeforces.com/contest/549/submission/11476513
A faster way of `scanf`, but it will not help you, because your
algorithm is slow.
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 10:58:33 UTC, Kagamin wrote:
On Saturday, 23 May 2015 at 02:36:14 UTC, Dennis Ritchie wrote:
For example, the code in Python looks quite natural:
a = [[int(j) for j in input().split()] for i in range(n)]
About D-code, I can not say:
auto a = stdin
.byLine
.map!(l => l.splitter.map!(to!int).array)
.take(n);
Well, list comprehension is built into language in python (and
not in D), such level of support is definitely more streamlined.
Yes, but D is also possible to create a strong inclusion of list
comprehensions. Here's the proof:
https://github.com/pplantinga/delight
Probably the coolest feature in Delight is list comprehensions.
Delight uses functions in std.algorithm to generate an iterable
range. The syntax is similar to Python's. See the last two
lines of the code above for an example.
print { i * 2 for i in 0 .. 5 where i ^ 2 less than 5 }
# prints [0, 2, 4]
Re: Is it possible to add items to the arrays and hashes at compile time?
On Wednesday, 10 June 2015 at 17:43:36 UTC, Ali Çehreli wrote: On the other hand, if it's a manifest constant (enum, const static, etc.) then by definition it cannot be mutated. If we allowed mutation of compile-time expressions, then we would have a complicated language. Unfortunately, the halting problem says that the analyzer does not exist. Although I don't believe it! enum i = 42; enum j = foo(i);// Did foo() use 42 or 43? i = 43; enum k = foo(i);// Did foo() use 42 or 43? How can an enum value be changed? I find the above confusing. So in fact, if `int` is evaluated at compile time, then we won't need constants or enums. Because they almost would not make sense. Although the issues associated with immutability, complex, I think they can be solved differently. The great thing about D's CTFE is that we can use arbitrarily complex expressions as long as they are available at compile time. For example, it is possible to make 'i' above a foreach loop variable and call foo() with different values. There is nothing great. Everything is based on constexpr of C++. I want something more revolutionary :) What is your use case? I feel like it can be solved by other means. There is no precedent special :) I just want to know more about the possibilities of D and the possibility of its compiler. D made me a terrible interest in compilers :)
Re: Is it possible to add items to the arrays and hashes at compile time?
On Wednesday, 10 June 2015 at 17:13:34 UTC, anonymous wrote: On Wednesday, 10 June 2015 at 17:00:34 UTC, Dennis Ritchie wrote: Isnt it possible to come up with the interpreter compile-time, which will determine the operating time of the program at runtime at compile time. Sounds like the halting problem. So, no, generally this is not possible. Thanks. I had never heard of the halting problem. This is exactly what I wanted to know.
Re: Is it possible to add items to the arrays and hashes at compile time?
On Wednesday, 10 June 2015 at 07:15:26 UTC, Ali Çehreli wrote: My phrasing was off: By definition, initialization happens once. :) What I meant is, once initialized, a compile-time variable cannot be reassigned. The reason is, to effect compile time evaluation, one needs to use 'enum' (or 'static const') but 'enum' is a literal, i.e. it cannot be modified. As I've shown, it is possible to use an expression that will be used as the value of the compile-time variable. As long as it is evaluable at compile time, the expression can be arbitrarily complex. I understand your phrase :) I don't understand why the variables at compile time cannot be reassigned. I.e. why can't we use `int` instead of `enum` or `immutable`? Isnt it possible to come up with the interpreter compile-time, which will determine the operating time of the program at runtime at compile time. And if this time is small, it is possible to reassign variables at compile time more than once. Maybe it's something out of science fiction, but still. Is it possible somehow to create a more complex compilation process, which can reassign variables more than once?
Re: Is it possible to add items to the arrays and hashes at compile time?
On Wednesday, 10 June 2015 at 03:38:32 UTC, Ali Çehreli wrote:
The way I understand it and the way it makes sense to me, :)
variables that are generated at compile time can be initialized
only once. It is not possible after initialization. However,
the initialization of the variable can be as complex as needed:
Thanks. It turns out I can do this:
import std.stdio;
auto merge(Hashes)(Hashes[] hashes...) {
int[][int][int] result;
foreach (hash; hashes) {
foreach (key, value; hash) {
result[key] = value;
}
}
return result;
}
enum firstPart = [1 : [ 1 : [1, 1] ] ];
enum secondPart = [2 : [ 2 : [2, 2] ] ];
int[][int][int] init_ctHash(int i) {
auto result = merge(firstPart, secondPart);
result[i] = [ i : [i, i] ];
return result;
}
void main() {
enum int[][int][int] ctHash = init_ctHash(5);
enum t = merge(ctHash, init_ctHash(6));
writeln(t);
}
But I can not do so:
enum int[][int][int] ctHash = init_ctHash(5);
ctHash = merge(ctHash, init_ctHash(6));
I have a question: why variables may not be initialized more than
once? Why can't they to resave at compile time?
Re: Is it possible to add items to the arrays and hashes at compile time?
On Sunday, 7 June 2015 at 15:20:17 UTC, Ali Çehreli wrote:
/* Some function that generates an AA */
Thanks. Beautiful code, but I want a little more :)
/* Some function that generates an AA */
int[][int][int] initHash(int i)
{
/* It is nice to see that this function is not called at run
time */
if (!__ctfe) {
import std.stdio;
writefln("%s is called at run time", __FUNCTION__);
}
return [i : [ i : [i, i] ] ];
}
/* Question: Is there a function to merge two AAs? */
int[][int][int] merge(Hash)(Hash[] hashes...)
{
/* It is nice to see that this function is not called at run
time */
if (!__ctfe) {
import std.stdio;
writefln("%s is called at run time", __FUNCTION__);
}
int[][int][int] result;
foreach (hash; hashes) {
foreach (key, value; hash) {
result[key] = value;
}
}
return result;
}
/* These three are generated at compile time */
enum firstPart = initHash(1);
enum secondPart = initHash(2);
enum int[][int][int] ctHash = merge(firstPart, secondPart);
void main()
{
import std.stdio;
static if (!(4 in ctHash)) {{
// ...
}}
ctHash[4][4] ~= [4, 4]; // I want this to work at compile time :)
// Possible?
static if (!!(4 in ctHash)) {{
// ...
}}
}
Re: Consevutive calls to r.front
On Monday, 8 June 2015 at 01:29:19 UTC, Dennis Ritchie wrote: Here is how it is implemented in the book of Andrew: Sorry, *Andrei.
Re: Consevutive calls to r.front
On Monday, 8 June 2015 at 01:15:30 UTC, Mike Parker wrote:
I know how to use a range :) What I'm asking about is a
requirement on implementing front on a custom range. Is there a
rule that says when I implement my own range, consecutive calls
to front must return the same value until popFront is called?
Example:
Is this a valid implementation of front?
auto front() { return _member++; }
Or must it be this:
auto front() { return _member; }
void popFront() { ++_member; }
My current understanding is that the former is incorrect, but
I'm looking for confirmation of that. I can't find it written
down anywhere.
Here is how it is implemented in the book of Andrew:
@property bool empty(T)(T[] a) { return a.length == 0; }
@property ref T front(T)(T[] a) { return a[0]; }
void popFront(T)(ref T[] a) { a = a[1 .. $]; }
Re: Consevutive calls to r.front
The foreach loop takes place in a for loop like this:
import std.range;
for (auto __c = 5.iota; !__c.empty; __c.popFront) {
auto elem = __c.front;
}
Re: Consevutive calls to r.front
On Monday, 8 June 2015 at 00:42:12 UTC, Mike Parker wrote:
When implementing a custom range, is it correct to say that
consecutive calls to r.front with no intervening calls to
popFront should return the same value?
Yes. For examle:
import std.stdio, std.range;
template foo(T) {
auto foo(R)(R range) {
while (!range.empty) {
writeln(range.front);
// .front --> the first element of the range
range.popFront;
// .popFront --> to extract the first element of the
range
}
}
}
void main() {
foo!(int[])([1, 2, 3]);
}
Re: How to remove the key from the `redBlackTree` with comparator" a <= b "?
On Sunday, 7 June 2015 at 19:11:25 UTC, anonymous wrote:
On Sunday, 7 June 2015 at 19:04:08 UTC, Dennis Ritchie wrote:
auto rbt = redBlackTree!("a <= b", int)(1, 2, 3, 4, 5);
writeln(rbt.upperBound(3)); // prints [3, 4, 5]
How do I do with the comparator "a < b" ?
Use equalRange to get the elements that equal 3, too:
writeln(std.range.chain(rbt.equalRange(3), rbt.upperBound(3)));
Thank you!
Re: How to remove the key from the `redBlackTree` with comparator" a <= b "?
On Sunday, 7 June 2015 at 18:50:47 UTC, anonymous wrote:
On Sunday, 7 June 2015 at 18:42:58 UTC, Dennis Ritchie wrote:
How do I remove the key from the `redBlackTree` with
comparator "a <= b" ?
Do not use '<=' as a comparison function with RedBlackTree. It
doesn't meet the requirements.
Quoting the documentation [1]:
Note that less should produce a strict ordering. That is, for
two unequal elements a and b, less(a, b) == !less(b, a).
less(a, a) should always equal false.
This doesn't hold for '<='.
OK. But I want to return a `upperBound` segment with the included
`key`. It does not suit me:
auto rbt = redBlackTree!("a < b", int)(1, 2, 3, 4, 5);
writeln(rbt.upperBound(3)); // prints [4, 5]
I want it to be so:
auto rbt = redBlackTree!("a <= b", int)(1, 2, 3, 4, 5);
writeln(rbt.upperBound(3)); // prints [3, 4, 5]
How do I do with the comparator "a < b" ?
How to remove the key from the `redBlackTree` with comparator" a <= b "?
I understand that `removeKey` works only with the comparator "a <
b":
http://dlang.org/phobos/std_container_rbtree.html#.RedBlackTree.removeKey
Removes elements from the container that are equal to the given
values according to the less comparator.
How do I remove the key from the `redBlackTree` with comparator
"a <= b" ?
auto rbt = redBlackTree!("a <= b", int)(1, 2, 3, 4, 5, 6, 7);
rbt.removeKey(6);
foreach (key; rbt)
write(key);
// prints 1234567
Re: Is it possible to add items to the arrays and hashes at compile time?
On Sunday, 7 June 2015 at 12:43:17 UTC, Nicholas Wilson wrote: or enum I suspect that enum can not add elements to the array.
Re: Is it possible to add items to the arrays and hashes at compile time?
On Sunday, 7 June 2015 at 12:42:12 UTC, Nicholas Wilson wrote:
On Sunday, 7 June 2015 at 12:30:12 UTC, Dennis Ritchie wrote:
try using a pure function + static e.g.
int[][int][int] somePureDefaultHash() pure
{
... //initialise it here
}
...
static hash = somePureDefaultHash();
static int[][int][int] hash;
hash[4][6] ~= [34, 65];
static if (!!(4 in hash)) {}
// Error: static variable hash cannot be read at compile time
Is it possible to add items to the arrays and hashes at compile time?
Does D the ability to add items to arrays and hashes at compile time? For example, how do I do it in compile time?: int[][int][int] hash; hash[4][6] ~= [34, 65]; hash[5][7] ~= [4, 78, 21];
Re: The problem with the value that is returned from the condition in `static if`. Bug or feature?
On Sunday, 7 June 2015 at 11:33:56 UTC, Marc Schütz wrote:
Not true:
immutable y = 1;
enum x = &y;
You can even do pointer arithmetics:
auto foo() {
auto x = [1,2,3,4];
auto y = &x[1];
return y[2];
}
pragma(msg, foo());
Then I do not see any problems hindering satisfy my report :)
Re: C++ static-if; how is it so different?
On Sunday, 7 June 2015 at 02:38:57 UTC, lobo wrote: If anyone knows why the proposal claims to be so different from D's static-if (modulo the restrictions mentioned) I'd be interested to know why. http://forum.dlang.org/post/mke22o$2l9i$1...@digitalmars.com
Re: The problem with the value that is returned from the condition in `static if`. Bug or feature?
On Sunday, 7 June 2015 at 03:04:38 UTC, lobo wrote:
On Sunday, 7 June 2015 at 03:01:15 UTC, lobo wrote:
On Saturday, 6 June 2015 at 17:06:37 UTC, Dennis Ritchie wrote:
[snip]
`static if(5 in hash) {}` will not work because (5 in hash)
returns a pointer to the value or null if the key oesn't exist.
bye,
lobo
just to be clear, you cannot have a pointer to anything at
compile time because it doesn't exist and IMO changing 'in' to
behave differently for static-if compared runtime if would be
bad.
This, of course, it is logical, but it somehow works:
immutable hash = [1 : 3, 5 : 7];
static if (!!(5 in hash))
writeln("OK"); // prints OK
Re: The problem with the value that is returned from the condition in `static if`. Bug or feature?
On Saturday, 6 June 2015 at 18:16:28 UTC, sigod wrote: On Saturday, 6 June 2015 at 17:06:37 UTC, Dennis Ritchie wrote: Pulls whether this issue? Or is it normal? http://dlang.org/version.html#staticif: StaticIfCondition: static if ( AssignExpression ) AssignExpression is implicitly converted to a boolean type, and is evaluated at compile time. The condition is satisfied if it evaluates to true. It is not satisfied if it evaluates to false. So, I suppose it's should work without casting to bool or `!is` operator. I reported this: https://issues.dlang.org/show_bug.cgi?id=14659
The problem with the value that is returned from the condition in `static if`. Bug or feature?
Hi,
No wonder that it works, because it is the legacy C++ (and I like
that everything is different from zero is true):
if (5)
writeln("OK"); // prints OK
In the `static if` this condition also works perfectly:
static if (5)
writeln("OK"); // prints OK
Here idiomatic version check in the hash key:
int[int] hash = [1 : 3, 5 : 7];
if (hash.get(5, false))
writeln("OK"); // prints OK
In the `static if` this condition also works perfectly:
immutable hash = [1 : 3, 5 : 7];
static if (hash.get(5, false))
writeln("OK"); // prints OK
It's not quite idiomatic version to check if a key in the hash:
int[int] hash = [1 : 3, 5 : 7];
if (5 in hash)
writeln("OK"); // prints OK
The problem is that the `static if` it does not work:
immutable hash = [1 : 3, 5 : 7];
static if (5 in hash)
writeln("OK");
// Error: expression &[1:3, 5:7][5]
// is not constant or does not evaluate to a bool
You have to write something like that :)
immutable hash = [1 : 3, 5 : 7];
static if (!!(5 in hash))
writeln("OK"); // prints OK
Pulls whether this issue? Or is it normal?
Re: Emulation macros and pattern matching on D
On Friday, 5 June 2015 at 20:14:51 UTC, Steven Schveighoffer wrote: On 6/5/15 4:03 PM, Dennis Ritchie wrote: It would be very good, because many have long been trying to implement this functionality handmade :) http://www.prowiki.org/wiki4d/wiki.cgi?DanielKeep/shfmt Yes, unfortunately that version is BSD licensed, won't make it into phobos. I think that the developers of D will be able to write better if they take it! :D
Re: Emulation macros and pattern matching on D
On Friday, 5 June 2015 at 19:08:19 UTC, Steven Schveighoffer wrote: It's just so I didn't have to escape the quotes :D Otherwise it looks like this: return "writefln(\"mode " ~ mode ~ ": %s\", " ~ value ~ ");" But such an option is possible to do work? : D return `writefln(q"["mode]" ` ~ mode ~ `q"[: %s"]", ` ~ value ~ `);`; I think we can probably do a compile-time substitution processor like rust (and other languages, including php and ruby) which just uses the variable name inside a string with some escape around it. `~var~` is not very succinct, I like $var better. It would be very good, because many have long been trying to implement this functionality handmade :) http://www.prowiki.org/wiki4d/wiki.cgi?DanielKeep/shfmt
Re: Emulation macros and pattern matching on D
On Friday, 5 June 2015 at 14:31:19 UTC, anonymous wrote: You messed up the quotes. You might be mistaking backticks for something special, but they're basically just quotes. Yes, the sample program really made me think that gravis (backticks) - is something special...
Re: Emulation macros and pattern matching on D
On Friday, 5 June 2015 at 14:23:15 UTC, Steven Schveighoffer
wrote:
On 6/5/15 10:15 AM, Dennis Ritchie wrote:
Thanks. It looks really simple, but I still do not understand
the
concept of using mixins in full.
I do not understand why in this line:
return `writefln("mode ` ~ mode ~ `: %s", ` ~ value ~ `);`;
use the following syntax:
~ mode ~ , ~ value ~
Because what foo is constructing is a string that makes sense
in the *caller*, not inside foo. What those statements do is
concat the *value* of mode (i.e. "Y" or "X") and the *value* of
value (i.e. "3" or "2") to the string.
It's equivalent to rust using the ${e} to do variable
substitution.
Thank you. Now everything is clear. Syntax `${e}` in Rust simpler
than D ` ~ substitute the value ~ ` :)
Re: Emulation macros and pattern matching on D
On Friday, 5 June 2015 at 13:13:15 UTC, Steven Schveighoffer
wrote:
string foo(string mode, string value)
{
return `writefln("mode ` ~ mode ~ `: %s", ` ~ value ~ `);`;
}
void main()
{
mixin(foo("Y", "3"));
mixin(foo("X", "2"));
}
Thanks. It looks really simple, but I still do not understand the
concept of using mixins in full.
I do not understand why in this line:
return `writefln("mode ` ~ mode ~ `: %s", ` ~ value ~ `);`;
use the following syntax:
~ mode ~ , ~ value ~
For example, why here I can simply write:
void main() {
int b = 5;
mixin(`int a = b;`);
assert(a == 5);
}
Why should not I write like this:
void main() {
int b = 5;
mixin(`"int a = " ` ~ b ~ ` ";"`);
assert(a == 5);
}
Emulation macros and pattern matching on D
Macros and operation of pattern matching `=>` in Rust I can write
something like this:
macro_rules!foo {
(x => $e:expr) => (println!("mode X: {}", $e));
(y => $e:expr) => (println!("mode Y: {}", $e));
}
fn main() {
foo!(y => 3); // mode Y: 3
foo!(x => 2); // mode X: 2
}
How is it possible to simulate in D?
Re: Length of Dimension in Multidimensional Array?
On Friday, 5 June 2015 at 07:53:52 UTC, Ralf the Bat wrote:
Probably a stupid question, but how do I find the length of each
dimension in a multidimensional array?
I slightly modified the function deepDup, who came up Ali Çehreli
:)
http://beta.forum.dlang.org/post/mihl6m$1che$1...@digitalmars.com
import std.stdio, std.traits, std.range, std.algorithm;
auto deepLen(A)(A arr)
if (isArray!A)
{
writefln("%s.len = %s", arr, arr.length);
static if (isArray!(ElementType!A)) {
return arr.map!(a => a.deepLen).array;
} else {
return arr;
}
}
void main() {
auto arr = [1, 2, 3, 4], [0]], [[4, 3], [5, 6, 7];
arr.deepLen;
}
[1, 2, 3, 4], [0]], [[4, 3], [5, 6, 7].len = 1
1, 2, 3, 4], [0]], [[4, 3], [5, 6, 7.len = 1
[[[1, 2, 3, 4], [0]], [[4, 3], [5, 6, 7]]].len = 2
[[1, 2, 3, 4], [0]].len = 2
[1, 2, 3, 4].len = 4
[0].len = 1
[[4, 3], [5, 6, 7]].len = 2
[4, 3].len = 2
[5, 6, 7].len = 3
Re: Array declaration warning
I used to not even notice that if D declare an array in C-style,
and then indexing it will also in C-style :)
Actually, I have a small question. And what is the advantage of
indexing arrays D-style in front of a C-style arrays? Because
C-style indexing is much more familiar: first, we point line, and
then the columns.
import std.algorithm;
void main() {
int cArr[2][4];
assert(equal(cArr[], [[0, 0, 0, 0],
[0, 0, 0, 0]]));
int[2][4] dArr;
assert(equal(dArr[], [[0, 0],
[0, 0],
[0, 0],
[0, 0]]));
}
Re: string to char array?
On Tuesday, 2 June 2015 at 15:53:33 UTC, Alex Parrill wrote: A string is, by definition in D, a character array, specifically `immutable(char)[]`. It's not like, for example, Java in which it's a completely separate type; you can perform all the standard array operations on strings. Yes, I believe that this is a problem in D, and because when you create a multidimensional array mutable strings having real troubles with .deepDup. I think that will solve the problem of a new string data type is a built-in D, and because writing .dup, to create a mutated string, - it's really funny! This is problem!
Re: string to char array?
On Tuesday, 2 June 2015 at 15:07:58 UTC, Kyoji Klyden wrote: quick question: What is the most efficient way to covert a string to a char array? string s = "str"; char[] strArr = s.dup;
Re: Splitting a range into a range of tuples
On Monday, 1 June 2015 at 22:31:38 UTC, Adam wrote:
Hi,
I have a string of pairs of integers, where pairs are delimited
from each other by commas, and members of the pair are
delimited by a space. I'd like to end up with something like a
range of 2-tuples
I can offer this option:
import std.stdio, std.algorithm, std.array, std.range,
std.format, std.typecons;
void main() {
string s = "192 14, 301 3, 578 0, 0 17";
int[] arr; int tmp;
foreach (el; s.split) {
formattedRead(el, "%s", &tmp);
arr ~= tmp;
}
Tuple!(int, int)[] tup;
foreach (el; zip(arr.stride(2), arr.dropOne.stride(2))) {
tup ~= tuple(el[0], el[1]);
}
tup.sort!"a[0] > b[0]";
writeln(tup);
}
/*[Tuple!(int, int)(578, 0), Tuple!(int, int)(301, 3),
Tuple!(int, int)(192, 14), Tuple!(int, int)(0, 17)]*/
Re: Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
On Sunday, 31 May 2015 at 07:28:02 UTC, Ali Çehreli wrote:
So, you want to skip that extra func() call and have the code
be "inlined". That's one of the things what any decent
optimizing compiler does anyway.
Yes, I think that there is an extra function call, because DMD is
based on Zortech C++ backend, so I figured ... :)
I hear great things especially about ldc and that gdc is just
good enough. Of course, one needs to check the assembly output
to be sure that there is no extra function calls.
Ali
And yet in DMD I'm not sure :)
import std.stdio, std.algorithm;
static int idx;
void walk(R)(R range) {
while (!range.empty) {
range.front;
range.popFront;
}
}
struct Tap(alias func, R)
{
R range;
alias range this;
@property auto front()
{
func(range.front);
return range.front;
}
}
auto tap(alias func, R)(R range)
{
writeln(__FUNCTION__); // ???
return Tap!(func, R)(range);
}
void main() {
[5, 6, 7]
.map!(a => [idx++, a])
.tap!((a) { writeln(a[1..$]); })
.walk;
}
Re: Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
On Sunday, 31 May 2015 at 06:04:40 UTC, Dennis Ritchie wrote: mixin(newStr[0 .. $ - 4] ~ `[idx,` ~ newStr[$ - 4 .. $]); mixin(newStr[0 .. $ - 4] ~ `idx,` ~ newStr[$ - 4 .. $]);
Re: Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
On Saturday, 30 May 2015 at 23:58:44 UTC, Ali Çehreli wrote:
On 05/30/2015 12:19 PM, Dennis Ritchie wrote:
First, unfortunately, I don't understand you completely. Sorry
about that... :)
Nothing to worry about! Now you will understand me till the
end... :)
Regarding that, the intermediate range.front is already
available right before the .walk part. You can do anything at
that point. There was some proposals about a 'tap' algorithm
that could be used for debugging purposes. Here is a quick
implementation:
Yes, it is an intermediate stage of code that will help me to
explain what I want to get.
import std.stdio, std.algorithm;
static int idx;
void walk(R)(R range) {
while (!range.empty) {
range.front;
range.popFront;
}
}
struct Tap(alias func, R)
{
R range;
alias range this;
@property auto front()
{
func(range.front); // It's a necessary part of the
code! :)
return range.front;
}
}
auto tap(alias func, R)(R range)
{
return Tap!(func, R)(range);
}
void main() {
[5, 6, 7]
.map!(a => [idx++, a])
.tap!((a) { writeln(a[1..$]); }) /* <-- This can use
the
* lambda syntax as
well but
* note that the
return
* value of the
lambda is
* ignored. So I
think this
* syntax is more
* helpful. */
.walk;
}
Ali
I don't know, maybe it's something out of science fiction, but
here's what I want to do :)
struct Tap(alias func, R)
{
R range;
alias range this;
@property auto front()
{
immutable string myStr = `func(mixin("range.front"));`;
immutable string newStr = `mixin(myStr);`;
writeln(newStr); // I want them to be printed here
`writeln([5]);`
mixin(newStr[0 .. $ - 4] ~ `[idx,` ~ newStr[$ - 4 .. $]);
// I want them to be printed here `[0, 5];`
return range.front;
}
}
Is it possible to do using mixins or through any other means? Ie
I want to catch the moment when `func` is replaced by the
invocation of `writeln` :)
Re: Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
On Saturday, 30 May 2015 at 19:19:21 UTC, Dennis Ritchie wrote: I want to access the intermediate generation `range.front`. Is it possible? :) In other words, I want to expand the array to the application to him of 'writeln'!
Re: Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
On Saturday, 30 May 2015 at 06:50:09 UTC, Ali Çehreli wrote:
On 05/29/2015 06:07 PM, Dennis Ritchie wrote:
> Hi,
> This code prints the arrays:
> [5]
> [6]
> [7]
>
> import std.stdio, std.algorithm;
>
> static int idx;
Do you want to share that for the first element of every
two-element array or do you want to start from 0 for every
range?
I want to share...
> void walk(R)(R range) {
> while (!range.empty) {
> range.front;
> range.popFront;
> ++idx;
> }
> }
As a reminder, there is also the recent 'each', which is eager
as well.
But I want to do this is to `map` :)
> void main() {
> [5, 6, 7].map!(a => [a].writeln).walk;
> }
>
> How should I apply mixins to `range.front` to the program to
print the
> arrays:
> [0, 5]
> [1, 6]
> [2, 7]
Unless mixin required for another reason, there are other ways
of achieving the same.
I just want to present the results of the intermediate
performance (which I plan to reach through the mixin)
`range.front` as a string, to then modify it with the help of
mixin to get directly to the array.
> Ie I want to get something like this:
>
> void walk(R)(R range) {
> while (!range.empty) {
> // mixin(`[idx ~ "mixin("range.front")"[1 .. $]);`);
> range.popFront;
> ++idx;
> }
> }
>
> Can I do this?
>
> -
> Thank you for the function `walk` Mark Isaacson of
presentation DConf 2015:
> http://dconf.org/2015/talks/isaacson.pdf
The following program produces the desired output twice. The
first one starts from 0 for the index, the second one shares
the index as in your code.
import std.stdio, std.algorithm, std.range;
void main() {
zip(sequence!"n", [5, 6, 7])
.map!(a => [a.expand])
.each!writeln;
static int idx;
[5, 6, 7]
.map!(a => [idx++, a])
.each!writeln;
}
Thank you for your examples, but I want to do something else.
Ie I want to access the intermediate generation `range.front`
with two mixins or by other means. `range` is of type
`MapResult!(__lambda1, int[])([5, 6, 7], null)` — I want to get
the generation of this intermediate, i.e. something like
`range.front` --> `[5].writeln` and present `[5].writeln` as a
string, to modify the line like so `[5].writeln` -->
`[5].writeln`[1 .. $] --> `[idx ~ `[5].writeln`[1 .. $]` -->
`[idx, 5].writeln` with the help of mixins. :)
I want to access the intermediate generation `range.front`. Is it
possible? :)
Mixin - to get to the content-type `MapResult!(__lambda1, int[]).MapResult`
Hi,
This code prints the arrays:
[5]
[6]
[7]
import std.stdio, std.algorithm;
static int idx;
void walk(R)(R range) {
while (!range.empty) {
range.front;
range.popFront;
++idx;
}
}
void main() {
[5, 6, 7].map!(a => [a].writeln).walk;
}
How should I apply mixins to `range.front` to the program to
print the arrays:
[0, 5]
[1, 6]
[2, 7]
Ie I want to get something like this:
void walk(R)(R range) {
while (!range.empty) {
// mixin(`[idx ~ "mixin("range.front")"[1 .. $]);`);
range.popFront;
++idx;
}
}
Can I do this?
-
Thank you for the function `walk` Mark Isaacson of presentation
DConf 2015:
http://dconf.org/2015/talks/isaacson.pdf
Re: Replacing nested loops foreach using map/each/etc
On Monday, 25 May 2015 at 19:16:04 UTC, anonymous wrote:
On Monday, 25 May 2015 at 17:52:09 UTC, Dennis Ritchie wrote:
But why is the solution breaks down when `s = 1` ? :)
import std.stdio, std.algorithm, std.range;
int c;
const x = 12, y = 65, z = 50, s = 10;
Which is it, now? 4 or 5 zeros?
No difference!
void solve(Range)(Range r) {
cartesianProduct(r, r, r).filter!(i => i[0] * (y + 3 * z) +
i[1] * (y + 2 * z) + i[2] * (y + z) == s).each!dout;
}
void main() {
auto a = iota(0, x + 1).array;
solve(a);
writefln(`%s total`, c);
}
void dout(Tuple)(Tuple idx) {
++c;
}
-
http://rextester.com/XGDL26042
What do you mean it "breaks down"? Your original code doesn't
print anything for s = 10_000 or s = 100_000, either.
Excuse me, this is my blemish! I forgot that the constant `x`
depends on `s`. Everything works correctly:
import std.stdio, std.algorithm, std.range;
void solve(Range)(Range r) {
cartesianProduct(r, r, r).filter!(i => i[0] * (y + 3 * z) +
i[1] * (y + 2 * z) + i[2] * (y + z) == s).each!dout;
}
const y = 65, z = 50, s = 10;
const x = s / (y + z);
void main() {
auto a = iota(0, x + 1);
solve(a);
}
auto dout(Tuple)(Tuple idx) {
writefln(`%s apples`, idx[0] + idx[1] + idx[2]);
writefln(`%s gingerbread`, idx[0] * 3 + idx[1] * 2 + idx[2]);
writefln(`%s pharynx tea`, idx[0] * 3 + idx[1] * 2 + idx[2]);
writefln("Sour: %s; semi-acid: %s; sweet: %s.\n", idx[0],
idx[1], idx[2]);
}
-
http://rextester.com/MMCI9993
Re: Replacing nested loops foreach using map/each/etc
On Monday, 25 May 2015 at 17:19:27 UTC, Meta wrote:
`each` doesn't support braces. There are 4 ways to write a
function/delegate literal in D (with a few minor variations):
Short form:
function(int i) => i;
(int i) => i
(i) => i
i => i
Long form:
function(int i) { return i; }
(int i) { return i; }
(i) { return i; }
{ return 0; }
http://dlang.org/expression.html#FunctionLiteral
function
Thanks.
But why is the solution breaks down when `s = 1` ? :)
import std.stdio, std.algorithm, std.range;
int c;
const x = 12, y = 65, z = 50, s = 10;
void solve(Range)(Range r) {
cartesianProduct(r, r, r).filter!(i => i[0] * (y + 3 * z) + i[1]
* (y + 2 * z) + i[2] * (y + z) == s).each!dout;
}
void main() {
auto a = iota(0, x + 1).array;
solve(a);
writefln(`%s total`, c);
}
void dout(Tuple)(Tuple idx) {
++c;
}
-
http://rextester.com/XGDL26042
Re: Replacing nested loops foreach using map/each/etc
On Monday, 25 May 2015 at 16:41:35 UTC, Meta wrote:
import std.algorithm;
import std.range;
import std.stdio;
void main()
{
const x = 12, y = 65, z = 50, s = 1435;
auto a = iota(0, x + 1);
cartesianProduct(a, a, a)
.filter!(i => i[0] * (y + 3 * z)
+ i[1] * (y + 2 * z)
+ i[2] * (y + z)
== s)
.each!((idx)
{
writeln(idx[0] + idx[1] + idx[2]);
writeln(idx[0] * 3 + idx[1] * 2 + idx[2]);
writeln(idx[0] * 3 + idx[1] * 2 + idx[2]);
writeln(idx[0], idx[1], idx[2]);
});
}
Thanks. I do not even know what `each` support braces.
Re: Replacing nested loops foreach using map/each/etc
On Monday, 25 May 2015 at 15:06:45 UTC, Alex Parrill wrote:
Hint: Use `cartesianProduct` [1] with three iota ranges to
replace the foreachs, and `filter` to replace the if
[1]
http://dlang.org/phobos/std_algorithm_setops.html#.cartesianProduct
Thank you. Is it possible to replace the loop `foreach` function
`each` or `chunkBy` with the auxiliary functions?
import std.stdio, std.algorithm, std.range;
void main() {
const x = 12, y = 65, z = 50, s = 1435;
auto a = iota(0, x + 1);
foreach (idx; cartesianProduct(a, a, a).filter!(i => i[0] *
(y + 3 * z) + i[1] * (y + 2 * z) + i[2] * (y + z) == s)) {
writeln(idx[0] + idx[1] + idx[2]);
writeln(idx[0] * 3 + idx[1] * 2 + idx[2]);
writeln(idx[0] * 3 + idx[1] * 2 + idx[2]);
writeln(idx[0], idx[1], idx[2]);
}
}
-
http://rextester.com/HZP96719
Replacing nested loops foreach using map/each/etc
Hi,
Is it possible to write such a construction that could push
immediately to a conditional statement without using nested
loops? Ie organize search directly in the iterator if provided by
a map / each / iota and other support functions.
Ie I want to write this code shorter :)
import std.stdio;
void main() {
const x = 12, y = 65, z = 50, s = 1435;
foreach (i; 0 .. x + 1)
foreach (j; 0 .. x + 1)
foreach (k; 0 .. x + 1)
if (i * (y + 3 * z) + j * (y + 2 * z) + k * (y +
z) == s) {
writeln(i + j + k);
writeln(i * 3 + j * 2 + k);
writeln(i * 3 + j * 2 + k);
writeln(i, j, k);
}
}
-
http://rextester.com/SJTU87854
Re: Python's features, which requires D
On Sunday, 24 May 2015 at 15:53:24 UTC, Idan Arye wrote: But according to the Blub Paradox, your(Or mine. Or Paul Graham's) opinion on whether or not a stronger language than Lisp has appeared can not be trusted! Based on an article Graham about Blub Paradox, I can conclude that Blub Paradox programmers only acts on a certain age. It is possible that this occurs after the age of 25 years. And since I am under 25 years old, I think I can be trusted completely :) - Paul Graham: "This idea is rarely followed to its conclusion, though. After a certain age, programmers rarely switch languages voluntarily. Whatever language people happen to be used to, they tend to consider just good enough. ... But I don't expect to convince anyone (over 25) to go out and learn Lisp."
Re: Python's features, which requires D
On Sunday, 24 May 2015 at 14:15:55 UTC, Idan Arye wrote: This IS ironic, because Paul Graham claims lisp to be the most powerful, but if he have ever encounter a more powerful language he couldn't accept it is more powerful than lisp due to the very same "Blub Paradox" he describes himself. Probably! But, in my opinion, it has not yet appeared stronger language Lisp, so "Blub Paradox" is not yet threatened with Graham :)
Re: Python's features, which requires D
On Sunday, 24 May 2015 at 02:43:47 UTC, Idan Arye wrote: I'm a fan of lisp(Clojure being my favorite. Too bad it takes about a century just to load the runtime...), and yet I find it quite ironic that Paul Graham claims lisp to be the most powerful language right after claiming that programmers can't understand - and therefore disregard - the power of languages more powerful than the ones they use... This is not ironic, because I did neglect the power of Lisp, because not quite understand it fully :) The power of Lisp - his worst enemy. Strange Lisp syntax allows you to write powerful macros, which is unique in other languages, but many programmers do not understand Lisp syntax (and therefore may find it funny).
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 21:32:51 UTC, anonymous wrote: On Saturday, 23 May 2015 at 21:08:19 UTC, Dennis Ritchie wrote: Perhaps that's not the site, and in Windows. That's what gives me in CMD: 456 4 4 8 99 456 [[456, 4, 4, 8, 99, 456]13 546 std.conv.ConvException@C:\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(2013): Unexpected end of input when converting from type char[] to type int That's a different issue. Works fine for me in wine. You may be typing spaces before/after the numbers. Yes, I think I scored one space after 546.
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 21:09:45 UTC, weaselcat wrote: After another review, I think some of these conversions to D could be expressed much easier if the built-in slice had multidimensional slicing It was added in 2.066* but I don't think there's any plans to add support for it to slices. Actually not a bad idea: add to Phobos module std.multiarray. * - you can see an example at http://denis-sh.bitbucket.org/unstandard/unstd.multidimarray.html Embed multidimensional slices directly into the language is not very good, but in a separate module, why not...
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 20:44:37 UTC, cym13 wrote: Not sure what kind of meat you mean, but I really don't see much meat in ranges. Of course, this is 10 times better and easier to use than STL iterators C++. For me the most important feature D are mixins, which I, unfortunately, rarely use. I'm waiting for new features from D: for new designs, not simply the expansion of Phobos and fix bugs in DMD :) Should I wait for these new features? It seems to me that everyone is not enough to simply correct C++ — they all want a language in which many different sugar. In my opinion, sugar you can try to shake out of Lisp, if possible :) I think you are mistaken. The hard part about growing a programming language isn't adding features, it's finding the right core of features that are stable yet generic enough to answer everything in their own way. This is why C still is such a popular language, it hardly evolvevd since the begginning. It is also why Java in its time or Go know are popular among companies: they are boring, just boring. But they are stable. C++ wanted to address every problem, and look at it know. We have to develop a style, not more features. Python has its own style but every new feature (and they are rare) is very diligently examined. Most are refused. There is the python way. If python isn't the right tool for the job, then the best thing to do is finding another tool, not scotch an extension to the first one. I like python. I like D. I like other languages. Of course sometimes I'd like to have, say, UFCS in python or list comprehension in D. But D isn't the best language to do python, python is. And as there is a python way, there is a D way. This is not to say that we should dismiss any good concept of other languages, but those concepts fit in a philosophy, in an ecosystem. You may find it nonsense, but Paul Graham says that each language has its own power. He believes that Lisp is the most powerful language, and programmers who write in other languages, he said Blub programmers. Learn more about "The Blub Paradox" can be read in the article Graham: http://www.paulgraham.com/avg.html What about increasing the number of features and stability, I agree. You may need more stability. Based on the theory of Graham, I should point out that the level of power python clearly lower than D :)
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 20:57:10 UTC, anonymous wrote:
On Saturday, 23 May 2015 at 20:25:18 UTC, Dennis Ritchie wrote:
This does not work!
enum n1 = 5;
writeln(stdin.byLine
.map!(line => line.split(" ").map!(x => to!int(x)))
);
-
http://rextester.com/VGHZF81178
The code itself is ok.
That site has broken newlines. You can see here that
std.ascii.newline is different from what the site actually
feeds to the program: .
You can work around that by passing the correct line terminator
to byLine: .
Perhaps that's not the site, and in Windows. That's what gives me
in CMD:
456 4 4 8 99 456
[[456, 4, 4, 8, 99, 456]13 546
std.conv.ConvException@C:\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(2013):
Unexpected end of input when converting from type char[] to type
int
0x0040FD10 in pure @safe int std.conv.parse!(int,
char[]).parse(ref char[]) at
C:\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(2015)
0x00410C74 in pure @safe int std.conv.toImpl!(int,
char[]).toImpl(char[]) at
C:\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(1738)
0x0040FB92 in pure @safe int
std.conv.to!(int).to!(char[]).to(char[]) at
C:\D\dmd2\windows\bin\..\..\src\phobos\std\conv.d(296)
0x0040FB7E in pure @safe int
acm.main().__lambda1!(char[]).__lambda1(char[]).__lambda2!(char[]).__lambda2(char[])
0x00410DA7 in pure @property @safe int
std.algorithm.iteration.__T9MapResultS553acm4mainFZ17__T9__lambda1TAaZ9__lambda1MFAaZ9__lambda2TAAaZ.MapResult.front()
at C:\D\dmd2\windows\bin\..\..\src\phobos\
std\algorithm\iteration.d(548)
0x004122D4 in
D3std6format169__T11formatRangeTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iteration76A5C81813C007BD25AC82BE82F3551A66
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(240
9)
0x0041213F in
D3std6format169__T11formatValueTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iteration768E862681E57D43E301EA954AAC63F894
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(311
2)
0x004120AA in
D3std6format171__T13formatElementTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iterationC8BE2524D6E8B27505208FE77A7AABE7
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(261
9)
0x00411B89 in
D3std6format172__T11formatRangeTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iteration7956A969C910F877511562257DEEBA50CE
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(241
0)
0x00411A27 in
D3std6format172__T11formatValueTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iteration793B5F1700DB9877FAF5528C7A1A67E5DC
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(311
2)
0x00411991 in
D3std6format174__T13formatGenericTS3std5stdio4File17LockingTextWriterTS3std9algorithm9iterationD44607637B1FEE3931BFD9A68911D4FE
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(345
1)
0x0041185C in
D3std6format175__T14formattedWriteTS3std5stdio4File17LockingTextWriterTaTS3std9algorithm9iteratD57474F5CD8E0DF85B780AE37888E8BE
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\format.d(521
)
0x00411320 in
D3std5stdio4File129__T5writeTS3std9algorithm9iteration79__T9MapResultS213acm4mainFZ9__lambda1TSD37A9C7F430415C668F40B8F70856955
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\stdio.d(1200
)
0x0041120A in
D3std5stdio129__T7writelnTS3std9algorithm9iteration79__T9MapResultS213acm4mainFZ9__lambda1TS3stC41BC71D1E9C2BC78EB8446AC4667CCD
at C:\D\dmd2\windows\bin\..\..\src\phobos\std\stdio.d(2932
)
0x0040203D in _Dmain at
C:\Users\REiS\Documents\Projects\acm\acm\acm.d(21)
0x00427E06 in
D2rt6dmain211_d_run_mainUiPPaPUAAaZiZ6runAllMFZ9__lambda1MFZv
0x00427DDB in void rt.dmain2._d_run_main(int, char**, extern (C)
int function(char[][])*).runAll()
0x00427CF3 in _d_run_main
0x00427884 in main
0x0043E701 in mainCRTStartup
0x76BB7C04 in BaseThreadInitThunk
0x775AAD1F in RtlInitializeExceptionChain
0x775AACEA in RtlInitializeExceptionChain
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 19:22:40 UTC, Alex Parrill wrote: You seem to be focusing on D's arrays only, but the real meat is in ranges, which are more generic. Also note that the above solution doesn't allocate any of the ranges in the heap; they're all on the stack (as opposed to Python, where you have to allocate lists or use iterators+itertools). Also present ranges from the time of D1 and Tango, because there is nothing surprising about them. Need new features!
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 19:22:40 UTC, Alex Parrill wrote:
import std.algorithm;
import std.range;
import std.stdio;
import std.conv;
void main() {
enum n1 = 5;
writeln(stdin.byLine
.map!(line => line.split(" ").map!(x => to!int(x)))
);
writeln("--");
enum n2 = 6;
writeln(iota(n2)
.map!(i => chain(
repeat("2", i),
only("1"),
repeat("0", n2 - i - 1),
only("\n")
).joiner(" ")).joiner
);
}
(I omitted evens/odds because it's been addressed and fizzbuzz
because there's probably dozens of them floating around)
You seem to be focusing on D's arrays only, but the real meat
is in ranges, which are more generic. Also note that the above
solution doesn't allocate any of the ranges in the heap;
they're all on the stack (as opposed to Python, where you have
to allocate lists or use iterators+itertools).
This does not work!
enum n1 = 5;
writeln(stdin.byLine
.map!(line => line.split(" ").map!(x => to!int(x)))
);
-
http://rextester.com/VGHZF81178
Even if you wanted to write this:
enum n = 5;
writeln(stdin.byLine
.map!(line => line.split(" ").map!(x => to!int(x))).take(n)
);
-
http://rextester.com/COWE75794
That it's still not working. In my opinion, and should not work :)
You seem to be focusing on D's arrays only, but the real meat
is in ranges, which are more generic.
Not sure what kind of meat you mean, but I really don't see much
meat in ranges. Of course, this is 10 times better and easier to
use than STL iterators C++. For me the most important feature D
are mixins, which I, unfortunately, rarely use. I'm waiting for
new features from D: for new designs, not simply the expansion of
Phobos and fix bugs in DMD :) Should I wait for these new
features? It seems to me that everyone is not enough to simply
correct C++ — they all want a language in which many different
sugar. In my opinion, sugar you can try to shake out of Lisp, if
possible :)
Also note that the above solution doesn't allocate any of the
ranges in the heap; they're all on the stack (as opposed to
Python, where you have to allocate lists or use
iterators+itertools).
And yet I do not like how the function byLine. It seems to me
that we need analogues that will not work so damp as byLine.
All right. Next time I will try to combine features that are not
available in D, and of the faster languages: Erlang, Perl, Lisp,
Nim, Rust, Scala etc. :)
Re: Python's features, which requires D
On Saturday, 23 May 2015 at 10:58:33 UTC, Kagamin wrote: Well, list comprehension is built into language in python (and not in D), such level of support is definitely more streamlined. Well, what's to keep D more functions to work with slist and dlist ? In my opinion, lists in D completely bald :) After all, there is a module in Phobos std.array, so why not make the module std.list. Do lists in D can be done as powerful as arrays?
Re: Python's features, which requires D
By the way, Python has deepDup :) http://rextester.com/KBFA82886
Re: Python's features, which requires D
On Friday, 22 May 2015 at 05:31:38 UTC, Ali Çehreli wrote:
Here is my attempt:
import std.stdio;
import std.algorithm;
import std.conv;
import std.range;
void main()
{
// Replace 'none' with 'all' to activate.
version (none) {
const n = 5;
auto a = stdin
.byLine
.map!(l => l.splitter.map!(to!int).array)
.take(n);
writeln(a);
writeln("-");
}
{
const n = 6;
auto a = iota(n)
.map!(i => chain([2].replicate(i),
[1],
[0].replicate(n - i - 1)));
writefln("%(%(%s %)\n%)", a);
writeln("-");
}
{
const x = [ 1, 2, 3, 4, 5, 6 ];
writeln(x.stride(2));
writeln(x.dropOne.stride(2));
writeln("-");
}
{
// The internet does not need another fizz buzz. :p
}
}
Ali
Yes, it looks pretty good :) Thanks. But...
It seems to me that D lacks features that allow you to write
function readln/readln.strip/readln.split just inside the lambda.
stdin.byLine is a good feature, but it captures the entire input
stream, which I should handle all or take lambdas function
take(n) n lines and then still handle all of these lines right
away. Ie stdin.byline used everywhere is not always convenient!
For example, the code in Python looks quite natural:
a = [[int(j) for j in input().split()] for i in range(n)]
About D-code, I can not say:
auto a = stdin
.byLine
.map!(l => l.splitter.map!(to!int).array)
.take(n);
I can call the map with the existing array:
import std.stdio, std.algorithm, std.conv, std.array;
void main()
{
auto a = [1, 2, 3];
auto b = a.map!(c => c ~
readln.split.map!(to!int).array).array;
writeln(b);
}
-
http://rextester.com/MBUMHI13858
But I can not call the readln n times without a map:
import std.stdio, std.conv, std.algorithm, std.array, std.range;
void main() {
auto a = [1, 2, 3];
auto b = [readln.split.map!(to!int).array].take(3);
writeln(b);
}
-
http://rextester.com/KCJ9346
Ie readln function cycle is needed for, another lambda or revised
map! Is there a function in Phobos?
Re: Python's features, which requires D
On Friday, 22 May 2015 at 02:18:23 UTC, weaselcat wrote:
On Friday, 22 May 2015 at 01:52:30 UTC, Dennis Ritchie wrote:
off the top of my head, the last one can easily be done with
std.range.stride
import std.stdio, std.range;
void main()
{
int[] a = [ 1, 2, 3, 4, 5, 6 ];
writeln(stride(a, 2)); // [1, 3, 5] #odd #print(x[::2]) #OK
// [2, 4, 6] #even #print(x[1::2]) #no equivalent in D
writeln(stride(a[1..$], 2));
auto x = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
// [2, 6, 10] #print(x[1::4]) #no equivalent in D
writeln(stride(a[1..$], 4));
}
Yes, this is what you need (I often forget that the functions can
take ranges in D).
Maybe somewhere and nested loops "for" to fill the arrays lying
around :)
Re: Python's features, which requires D
On Friday, 22 May 2015 at 01:17:17 UTC, weaselcat wrote:
D doesn't have list comprehensions, so it's difficult to
directly port these.
I can not imagine how difficult it is to implement it in D, but
I'm pretty sure that nested for loops to fill arrays (in D, you
can call them differently, for example, force :)) will be very
useful thing, because Python is a veryIt is often used.
Besides, I do not understand what could be the problem with
nested loops in arrays, because std.algorithm.map works on the
principle of nested loops. I think that the biggest problem in
the implementation of this should not be. Excuse me if I'm wrong.
off the top of my head, the last one can easily be done with
std.range.stride
import std.stdio, std.range;
void main()
{
int[] a = [ 1, 2, 3, 4, 5, 6 ];
writeln(stride(a, 2)); // [1, 3, 5] #odd #print(x[::2]) #OK
// [2, 4, 6] #even #print(x[1::2]) #no equivalent in D
auto x = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
// [2, 6, 10] #print(x[1::4]) #no equivalent in D
}
Python's features, which requires D
Hi, I've collected some of Python's features. It seems to me that they are not in the D! Surely all this is in the D? :) http://rextester.com/CNQQR
Re: Dual conditions in D and Python
On Thursday, 21 May 2015 at 21:35:22 UTC, Ali Çehreli wrote:
We're almost there. :)
bool is_between(T0, T1, T2)(T0 what, T1 min, T2 max)
{
return (what >= min) && (what <= max);
}
void main()
{
if (5.is_between(4, 6)) {
// ...
}
}
Ali
A condition is that if, for example, that? :)
if (5 > 2 > -9 > -13 < 10 == 10 < 21 != 45):
print("OK")
-
http://rextester.com/JSC75231
import std.stdio;
void main()
{
if (5 > 2 &&
2 > -9 &&
-9 > -13 &&
-13 < 10 &&
10 == 10 &&
10 < 21 &&
21 != 45)
writeln("OK");
}
-
http://rextester.com/AZFL70044
Re: Dual conditions in D and Python
Something I sometimes do for strictly personal projects:
import std.typecons : ω = tuple;
import std.typetuple : Ω = TypeTuple;
void main()
{
auto a = 1, b = 2;
Ω!(a, b) = ω(b, a);
assert(a==2 && b==1);
}
On Thursday, 21 May 2015 at 19:05:16 UTC, Steven Schveighoffer
wrote:
On 5/21/15 12:57 PM, Dennis Ritchie wrote:
Hi,
In Python I can write this:
if (4 <= 5 <= 6):
print ("OK")
-
http://rextester.com/NNAM70713
In D, I can only write this:
import std.stdio;
void main() {
if (4 <= 5 && 5 <= 6)
puts("OK");
}
-
http://rextester.com/FICP83173
I wanted to ask what is the reason? Maybe the program on
Python's slower
because of this? Or legacy C/C++ affected D?
There is this possibility:
switch(5){
case 4: .. case 6:
}
You could also make some nifty abuse-of-syntax types:
struct Between(T)
{
T low;
T high;
bool opBinaryRight!(op : "in")(T val) { return val >= low &&
val <= high;}
}
auto between(T)(T low, T high) { return Between!T(low, high); }
if(5 in between(4, 6))
:)
-Steve
All this, of course, looks good, but what about the principle of
the ideal programming language :)
"In the end I want to focus on one philosophical principle, which
lies at the basis of my ideas about the ideal programming
language. Typically, during the discussion in the forums, when
you start to talk in a language that is not X features Y, be sure
there is someone who will say: Why, that's if you take the
features A, B and C, and screw them crutches D, E, F, then we
will get almost Y. Yes, it is. But I do not like this approach.
One can imagine that such programmers want some complicated way
through the maze. You can go through the maze, but the way the
curve and non-obvious. I also want to be instead of the labyrinth
has a large area, on which from any point to any other one would
go in a straight line. Just a straight line."
-
The quotation is taken from the article:
http://habrahabr.ru/post/257875/
Re: Dual conditions in D and Python
On Thursday, 21 May 2015 at 17:43:25 UTC, Jonathan M Davis wrote: No C-based language allows what python does, and based on operators work in C-based languages, what python is doing simply doesn't fit or make sense. What happens in C/C++/D/Java/C#/etc. land is that 4 <= 5 results in a bool, at which point you'd end up with a comparison between that bool and 6, which is _not_ something that you want. But with other operators _is_ very much what you'd want. Operator chaining works in the same way across all operators in C-based languages, and trying to make 4 <= 5 <= 6 be equivalent to 4 <= 5 && 5 <= 6 would make it so that they weren't consistent. And it wouldn't make the language any more powerful, because you can quite easily just do 4 <= 5 && 5 <= 6 instead of 4 <= 5 <= 6. It only costs you a few characters and results in the language being far more consistent. I'm honestly quite surprised that python would allow such a thing, but they seem to do a lot of stuff that most programmers from C-based languages (especially C++) would think is crazy. - Jonathan M Davis Yes, of course, some of Python's design for C ++ - programmers will look crazy, but they are worth it :) elif instead of else if: http://rextester.com/WOSH30608 The parallel exchange values: http://rextester.com/TPUD51604
Re: Dual conditions in D and Python
On Thursday, 21 May 2015 at 17:17:29 UTC, Alex Parrill wrote: http://wiki.dlang.org/Language_Designs_Explained#Why_does_D_not_support_chaining_comparison_operators.3F Backward compatibility with C is nice but on the other hand it is a road to nowhere! Because of this compatibility, I'm compelled to write return instead of ret and else if instead of elif :) I think to create a truly correct C++, it was necessary to completely abandon the backward compatibility with C.
Dual conditions in D and Python
Hi,
In Python I can write this:
if (4 <= 5 <= 6):
print ("OK")
-
http://rextester.com/NNAM70713
In D, I can only write this:
import std.stdio;
void main() {
if (4 <= 5 && 5 <= 6)
puts("OK");
}
-
http://rextester.com/FICP83173
I wanted to ask what is the reason? Maybe the program on Python's
slower because of this? Or legacy C/C++ affected D?
Re: The analogue of "fill-pointer" in D
On Monday, 18 May 2015 at 17:14:46 UTC, Steven Schveighoffer wrote: capacity is analogous to the number of elements in the vector (as returned by array-dimension according to https://www.cs.cmu.edu/Groups/AI/html/cltl/clm/node162.html). arr.length is analogous to the fill pointer. example: int[] arr = new int[](5); assert(arr.capacity > 5); assert(arr.length == 5); arr.reserve(100); // expand arr memory block to be able to hold *at least* 100 ints assert(arr.capacity >= 100); assert(arr.length == 5); auto ptr = arr.ptr; // for later assert arr ~= 1; // increment length by 1, 'fill in' tail of array with '1' // this should demonstrate how it works assert(arr.length == 6); // new fill pointer assert(arr.capacity >= 100); // capacity unchanged assert(arr.ptr is ptr); // array still lives in same memory block Apologies for not translating to lisp, I don't know it. -Steve Thank you. This is what you need!
Re: How to create a mutable array of strings?
On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: It's annoying to have to dup each one. Yes, it's really annoying. However, the problem can be solved as follows: http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: But, you do have a couple other possibilities: auto s = ["foo".dup, "bar".dup]; import std.algorithm : map; import std.array : array; auto s = map!(a => a.dup)(["foo", "bar"]).array; // this will needlessly allocate an array for the strings Now imagine that you have a multi-dimensional array of strings. This will not work: auto s = map!(a => a.dup)([["foo", "baz"], ["bar", "test"]]).array; You have to apply to each line .dup :) auto s = [["foo".dup, "baz".dup], ["bar".dup, "test".dup]]; s[1][0][1] = 't'; On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: But really, a string is immutable. There's not a way around that. A string is the most basic level of array primitive, not even mutable arrays of non-char types have that, and it's an annoyance. From there, you have to build the data out of ROM into the heap. Thank you. I do not know. And yet, the problem is easily solved. You just have to add .deepDup Phobos: http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org
Re: The analogue of "fill-pointer" in D
On Monday, 18 May 2015 at 12:49:56 UTC, Kagamin wrote: Filling a buffer is usually done this way: http://dlang.org/phobos/std_stdio.html#.File.rawRead Here such example, the task. There is a flow stream, associated, for example, with any socket. It wrote several bytes at a time. To once again not to pull the socket, we start buffer as an array with Phill-pointer. Adding byte array - using the vector-push. When the buffer is stuffed, dump it into the stream and moves pointer to zero. How to do it with the help of readRaw or there writeRaw?
Re: How to create a mutable array of strings?
On Monday, 18 May 2015 at 14:43:33 UTC, Steven Schveighoffer
wrote:
Right, you'd apply the map/array combo to each element:
Yes, I knew it.
alias m = map!(a => a.dup); // too bad can't do array as well
auto s = [m(["foo", "baz"]).array, m(["bar", "test"]).array];
Or to get even more crazy:
auto s = map!(a => map!(a => a.dup)(a).array)(/* your input
array */).array;
Imagine a five-dimensional array will be :)
But this means you are duping more of the array literal than
you really should.
It's likely helpful to have somewhere in std.array a dupArray
function that does map!(a => a.dup).array work in one go (and
without making a temporary array):
auto s = [dupArray("foo", "baz"), dupArray("bar", "test")];
Yes, it would be nice. I believe that Phobos need such function.
deepDup would dup the whole thing. All you need to dup is the
string literals, as array literals constructed at runtime are
on the heap (and mutable) already. The literal already is
wasted even in my original suggestion, but this is doubly
wasteful.
Right.
Re: The analogue of "fill-pointer" in D
On Monday, 18 May 2015 at 10:14:33 UTC, Kagamin wrote: On Monday, 18 May 2015 at 08:21:38 UTC, Dennis Ritchie wrote: Hi, In Common Lisp, there is such a thing as a fill-pointer (Example 5): http://www.tutorialspoint.com/lisp/lisp_arrays.htm Does D some equivalent? Data stored in the array is indicated by the array length property, use capacity to figure out extra available space: http://dlang.org/phobos/object.html#.capacity No, afraid not. Function capacity is not an analogue of fill-pointers! Lisp-programmer explains the usefulness of fill-pointers as follows: "Fill pointer "cuts" the tail of the vector. For example, vector elements 100, but if you set the fill pointer equal to 3, the length of the array (returned by length) will be equal to 3. The remaining elements are not visible. It seems to be nonsense. But this is nonsense, ideal for buffers. If the buffer is implemented as an array, then fill pointer just marks the boundary of the filled part of the buffer, and adding a buffer (moving away from the fill pointer-a) is carried out using the vector-push. Or a buffer can be filled with the format-a. If you work with the same buffer C, fill pointer simulates a pointer to the last completed item."
The analogue of "fill-pointer" in D
Hi, In Common Lisp, there is such a thing as a fill-pointer (Example 5): http://www.tutorialspoint.com/lisp/lisp_arrays.htm Does D some equivalent?
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 10:05:34 UTC, Daniel Kozak wrote: Ouch ignore this one :D Yes, it will not work with multidimensional arrays :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:37:56 UTC, Daniel Kozak wrote: So maybe this one would be ok with you too :) auto s = to!(char[][])(["foo", "bar"]); Now it works :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:36:33 UTC, anonymous wrote:
On Sunday, 17 May 2015 at 09:26:15 UTC, Dennis Ritchie wrote:
And no crashes on Windows :)
Yeah, on windows it's even worse.
void main()
{
auto s = cast(char[][])["foo", "bar"];
s[1][1] = 't';
import std.stdio;
writeln("bar");
}
Yes exactly.
Re: How to create a mutable array of strings?
I remembered code Ali Çereli. It really helped:
http://forum.dlang.org/thread/ulhtlyxxclihaseef...@forum.dlang.org#post-mihl6m:241che:241:40digitalmars.com
-
import std.stdio, std.traits, std.range, std.algorithm;
auto deepDup(A)(A arr)
if (isArray!A)
{
static if (isArray!(ElementType!A)) {
return arr.map!(a => a.deepDup).array;
} else {
return arr.dup;
}
}
void main() {
auto s = ["foo", "bar"].deepDup;
s[1][1] = 't';
writeln(s);
}
-
http://rextester.com/QBFH12695
P.S. Need to enable deepDup in Phobos.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:24:19 UTC, anonymous wrote: On Sunday, 17 May 2015 at 09:20:17 UTC, Dennis Ritchie wrote: On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied. Remember that Daniel Kozak wrote "if you are sure thats what you really need". I'm confident that you're not sure it's what you need. For starters, this crashes on linux: auto s = cast(char[][])["foo", "bar"]; s[1][1] = 't'; And no crashes on Windows :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied.
Re: How to create a mutable array of strings?
This option is also a strange: char[][] s = ["foo".dup, "bar".dup]; s[1][1] = 't'; In my opinion, you need to add to D keyword mutable.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:06:40 UTC, Dennis Ritchie wrote: Hi, It seems to me, or D do not create mutable array of strings? How to create a mutable equivalent of a string array? - string[] s = ["foo", "bar"]; // s[1][1] = 't'; // immutable expression s[1][1] It's uncomfortable: - char[][] s = [['f', 'o', 'o'], ['b', 'a', 'r']]; s[1][1] = 't';
