Re: CTFE question

2012-09-03 Thread Philippe Sigaud 
On Mon, Sep 3, 2012 at 4:08 PM, bearophile  wrote:

>> Worth a bug report?
>
>
> Yeah. CTFE must give the same results when CTFE works.

http://d.puremagic.com/issues/show_bug.cgi?id=8614

Re: CTFE question

2012-09-03 Thread bearophile 

Philippe Sigaud:


Worth a bug report?


Yeah. CTFE must give the same results when CTFE works.

A simpler test case for Bugzilla:

import std.stdio;
int[] foo(int[] data) {
 foreach (i, ref x; data) {
 x++;
 i++;
 }
 return data;
}
void main() {
enum result1 = foo([10, 20, 30, 40]);
auto result2 = foo([10, 20, 30, 40]);
writeln(result1); // [11, 21, 31, 41]
writeln(result2); // [11, 20, 31, 40]
}

Bye,
bearophile

Re: CTFE question

2012-09-03 Thread Philippe Sigaud 
On Mon, Sep 3, 2012 at 1:27 PM, Don Clugston  wrote:


>> Godd adivce, except beware of using ++ and --, they don't work at
>> compile-time. I'm regularly caught unaware by this, particularly while
>> looping.
>
>
> Really? That's scary. Is there a bug report for this?

I re-tried this and I was mistaken: it's not ++ or --, it's changing
an iteration index at compile-time. My bad.

int[] indices(string s)
{
int[] store;
foreach(i,ch; s[0..$-1])
{
store ~= i;
if (s[i..i+2] == "aa")
i += 1; // also ++i or i++, no difference here
}
return store;
}

void main()
{
enum result1 = indices("aaabc");
auto result2 = indices("aaabc");

writeln(result1); // [0,1,2,3]
writeln(result2); // [0,2,3]
}

I know changing 'i' while iterating is not a good idea, but at least
in this case, CT-executed and RT-execution give a different result.
All my other tests with ++ and -- give correct results, sorry for the
bad publicity.

Worth a bug report?

Re: CTFE question

2012-09-03 Thread Don Clugston 

On 28/08/12 19:40, Philippe Sigaud wrote:

On Tue, Aug 28, 2012 at 2:07 PM, Chris Cain  wrote:

On Tuesday, 28 August 2012 at 11:39:20 UTC, Danny Arends wrote:


Ahhh I understand...

As a follow up, is it then possible to 'track' filling a
large enum / immutable on compile time by outputting a msg
every for ?

I'm generating rotation matrices for yaw, pitch and roll
at compile time which can take a long time depending on
how fine grained I create them.



I'm pretty sure there isn't. However, if you're just trying to develop/test
your algorithm, you could write a program that runs it as a normal function
(and just use writeln) as you develop it. After it's done, you remove the
writelns, mark the function as pure and it should work exactly the same in
CTFE.


Godd adivce, except beware of using ++ and --, they don't work at
compile-time. I'm regularly caught unaware by this, particularly while
looping.


Really? That's scary. Is there a bug report for this?

Re: CTFE question

2012-08-28 Thread Philippe Sigaud 
On Tue, Aug 28, 2012 at 2:07 PM, Chris Cain  wrote:
> On Tuesday, 28 August 2012 at 11:39:20 UTC, Danny Arends wrote:
>>
>> Ahhh I understand...
>>
>> As a follow up, is it then possible to 'track' filling a
>> large enum / immutable on compile time by outputting a msg
>> every for ?
>>
>> I'm generating rotation matrices for yaw, pitch and roll
>> at compile time which can take a long time depending on
>> how fine grained I create them.
>
>
> I'm pretty sure there isn't. However, if you're just trying to develop/test
> your algorithm, you could write a program that runs it as a normal function
> (and just use writeln) as you develop it. After it's done, you remove the
> writelns, mark the function as pure and it should work exactly the same in
> CTFE.

Godd adivce, except beware of using ++ and --, they don't work at
compile-time. I'm regularly caught unaware by this, particularly while
looping.


Danny is also using 0..360, which is a runtime value. There exists a
compile-time version of foreach which is automatically invoked
whenever you use foreach on a compile-time 'range' (aka, typetuple)

So:

template Loop(T...)
{
/* some code */
foreach(i,Type; T)
pragma(msg, i);
}

will work.

So, a way to get what the OP wanted is to create a tuple of the
required length. Since integers are valid template arguments, we can
use them directly like this:

template staticRange(uint upto)
{
static if (upto == 0)
alias TypeTuple!() staticRange;
else
alias TypeTuple!(staticRange!(upto-1), upto-1) staticRange;
}

So staticRange!3 is the tuple 0,1,2. (staticRange!0 is empty)
You can foreach on it:

pure int[] testCTFE(){
  int[] r;
  pragma(msg, "Testing CTFE");

  foreach(i; staticRange!360){
r ~= i;
pragma(msg, i);
  }

  pragma(msg, "Done CTFE test");
  return r;
}


Of course, that means knowing the upper value at compile-time.

Re: CTFE question

2012-08-28 Thread bearophile 

Danny Arends:


Seems a bit strange that a discussion about yes/no
newline is keeping this from getting into DMD.


The ending newline is bad, because it unnecessarily kills some
use cases for this feature.

But I think the newline is not what is keeping it out of DMD.
It's just there are about a hundred open patches, and Walter is
currently implementing 64bits on Windows.

Bye,
bearophile

Re: CTFE question

2012-08-28 Thread Danny Arends 

On Tuesday, 28 August 2012 at 12:07:07 UTC, Chris Cain wrote:

On Tuesday, 28 August 2012 at 11:39:20 UTC, Danny Arends wrote:
I'm pretty sure there isn't. However, if you're just trying to 
develop/test your algorithm, you could write a program that 
runs it as a normal function (and just use writeln) as you 
develop it. After it's done, you remove the writelns, mark the 
function as pure and it should work exactly the same in CTFE.


Well it just seems some compilation runs take way longer (and 
more memory)

then others..Googling I found that I just got to wait for:

https://github.com/D-Programming-Language/dmd/pull/692

to be accepted. Seems a bit strange that a discussion about yes/no
newline is keeping this from getting into DMD.

Just basic ctfewrite support would help me a lot.

Gr,
Danny Arends

Re: CTFE question

2012-08-28 Thread Chris Cain 

On Tuesday, 28 August 2012 at 11:39:20 UTC, Danny Arends wrote:

Ahhh I understand...

As a follow up, is it then possible to 'track' filling a
large enum / immutable on compile time by outputting a msg
every for ?

I'm generating rotation matrices for yaw, pitch and roll
at compile time which can take a long time depending on
how fine grained I create them.


I'm pretty sure there isn't. However, if you're just trying to 
develop/test your algorithm, you could write a program that runs 
it as a normal function (and just use writeln) as you develop it. 
After it's done, you remove the writelns, mark the function as 
pure and it should work exactly the same in CTFE.

Re: CTFE question

2012-08-28 Thread Danny Arends 

Ahhh I understand...

As a follow up, is it then possible to 'track' filling a
large enum / immutable on compile time by outputting a msg
every for ?

I'm generating rotation matrices for yaw, pitch and roll
at compile time which can take a long time depending on
how fine grained I create them.

Gr,
Danny Arends
http://www.dannyarends.nl

On Tuesday, 28 August 2012 at 11:29:32 UTC, Chris Cain wrote:

On Tuesday, 28 August 2012 at 11:13:40 UTC, Danny Arends wrote:

Is this a bug or am I doing something wrong ??

Danny Arends
http://www.dannyarends.nl


You're doing something wrong, but I can see why the error 
message would confuse you.


Your problem is using those pragma(msg, ...) lines... They 
produce a message while something is being compiled, right? The 
CTFE function is ran _after_ it has been compiled. Hence i 
can't be read while the CTFE function is compiled.


So, to be clear, doing this:


-

import std.stdio;
import std.metastrings;

pure int[] testCTFE(){
  int[] r;
  pragma(msg, "Testing CTFE");
  foreach(i; 0 .. 360){
r ~= i;
//pragma(msg, Format!("Loop: %d",i));
  }
  pragma(msg, "Done CTFE test");
  return r;
}

immutable CTFEdata = testCTFE();
immutable CTFEdata2 = testCTFE();

void main(string[] args){ }



Produces just one output:
Testing CTFE
Done CTFE test


Because the pragmas are done _as it's compiled_, not as it's 
ran (even though CTFE is done "at compile time").

Re: CTFE question

2012-08-28 Thread Chris Cain 

On Tuesday, 28 August 2012 at 11:13:40 UTC, Danny Arends wrote:

Is this a bug or am I doing something wrong ??

Danny Arends
http://www.dannyarends.nl


You're doing something wrong, but I can see why the error message 
would confuse you.


Your problem is using those pragma(msg, ...) lines... They 
produce a message while something is being compiled, right? The 
CTFE function is ran _after_ it has been compiled. Hence i can't 
be read while the CTFE function is compiled.


So, to be clear, doing this:


-

import std.stdio;
import std.metastrings;

pure int[] testCTFE(){
  int[] r;
  pragma(msg, "Testing CTFE");
  foreach(i; 0 .. 360){
r ~= i;
//pragma(msg, Format!("Loop: %d",i));
  }
  pragma(msg, "Done CTFE test");
  return r;
}

immutable CTFEdata = testCTFE();
immutable CTFEdata2 = testCTFE();

void main(string[] args){ }



Produces just one output:
Testing CTFE
Done CTFE test


Because the pragmas are done _as it's compiled_, not as it's ran 
(even though CTFE is done "at compile time").

CTFE question

2012-08-28 Thread Danny Arends 

I have the following code:



import std.stdio;
import std.metastrings;

pure int[] testCTFE(){
  int[] r;
  pragma(msg, "Testing CTFE");
  foreach(i; 0 .. 360){
r ~= i;
pragma(msg, Format!("Loop: %d",i));
  }
  pragma(msg, "Done CTFE test");
  return r;
}

immutable CTFEdata = testCTFE();

void main(string[] args){ }

--

I expected this would compile and during compilation print:
Loop: 1 Loop:2, etc
However, I get a compilation error:

ctfe.d(9): Error: variable i cannot be read at compile time

Is this a bug or am I doing something wrong ??

Danny Arends
http://www.dannyarends.nl

Re: speeding up + ctfe question

2012-05-28 Thread maarten van damme 
I didn't use divisions or remainders, only multiplications. I've
changed it so it only uses addition and now it still doesn't
outperform a version that only checks odd's. it's not as fast as your
version where every index corresponds to i*2+1 because I fill every
even number with false...

Re: speeding up + ctfe question

2012-05-28 Thread jerro 
I tried using 6k+-1 for all primes and for some reason it 
performed
slower. I think I have something completely inefficient 
somewhere,

can't figure out where though.


You aren't, by any chance, using divisions or remainders? those
are much slower than, say, multiplications (unless the divisor
is a power of two and known at compile time, in which case
the compiler will optimize them to bitwise operations).

and I haven't tried with optimization on, first I want to get 
the
algorithm as good as possible before trying to squeeze out 
those extra

milliseconds :)


I prefer to compile with optimizations on when trying to
optimize something. That way I don't waste my time on
micro-optimizations that the compiler could do for me.

Re: speeding up + ctfe question

2012-05-28 Thread maarten van damme 
I tried using 6k+-1 for all primes and for some reason it performed
slower. I think I have something completely inefficient somewhere,
can't figure out where though.
I think it has something to do with me increasing k and then
multiplying with k while I could have simply added 6 to K...

and I haven't tried with optimization on, first I want to get the
algorithm as good as possible before trying to squeeze out those extra
milliseconds :)

Re: speeding up + ctfe question

2012-05-27 Thread jerro 

On Sunday, 27 May 2012 at 17:00:01 UTC, maarten van damme wrote:
ok, can't seem to reproduce the crashing. now on to optimizing 
my

sieve a bit more ,9 miliseconds for 1_000_000 is still to slow.
--
Er is zon buiten. Zonnige zondag namiddag met priemgetallen in 
de

plaats van buiten zitten. Tss tss. :-)
hoe? wie? x)


Have you tried turning optimization on? I get about 8ms with
your code with no flags and about 2.9 with -O -inline -release.

To optimize it further you could make a sieve that only works
with odd numbers. I get (https://gist.github.com/2817289) about
1ms that way. I'm sure it is possible to do much better, but
that would probably be much more work too.

Re: speeding up + ctfe question

2012-05-27 Thread maarten van damme 
ok, can't seem to reproduce the crashing. now on to optimizing my
sieve a bit more ,9 miliseconds for 1_000_000 is still to slow.
--
Er is zon buiten. Zonnige zondag namiddag met priemgetallen in de
plaats van buiten zitten. Tss tss. :-)
hoe? wie? x)

Re: speeding up + ctfe question

2012-05-27 Thread jerro 
I ran in two problems. It was extremely fast when sieving a 
byte array
of 1 million entries (without optimizations at all) but when 
trying
with 10_000_000 entries the program crashes before it even 
starts to

execute (main isn't reached).


You say it does compile, but then crashes immediatly? I can't
reproduce that. For me it is a compile time error if toSieve
is 16MB or more, but otherwise it runs fine. Anyway you should
use a dynamic array instead of a static one if you want really
large arrays.

Then I decided to benchmark the code and dmd fails to compile 
with

"Internal error: ..\ztc\cgcs.s 354".

I assume the first problem has to do with memory limits and 
that the

second is a little dmd bug.


It is a bug, all internal errors are. It looks like you can
avoid like this:

auto tmp=(benchmark!(f0)(1000));
int time=tmp[0].to!("msecs", int);

Re: speeding up + ctfe question

2012-05-27 Thread sclytrack 

On 05/27/2012 02:10 PM, maarten van damme wrote:

thank you :)

I wrote a sieve of aristotle because atkin's sieve needed waay to many
optimizations to beat aristotle's sieve by even a little bit so I
wanted to see if aristotle's was good enough.

I ran in two problems. It was extremely fast when sieving a byte array
of 1 million entries (without optimizations at all) but when trying
with 10_000_000 entries the program crashes before it even starts to
execute (main isn't reached).

Then I decided to benchmark the code and dmd fails to compile with
"Internal error: ..\ztc\cgcs.s 354".

I assume the first problem has to do with memory limits and that the
second is a little dmd bug. code is at
http://dl.dropbox.com/u/15024434/d/aristotleSieve.d


Yeah I get the same errors. And I'm not acquainted with the benchmark code.
--
http://dlang.org/concepts.html
isprime there says that 2 is not a prime.
enum result = isprime(2);
compile time enum "result" says false.
--
http://erdani.com/d/web/phobos-prerelease/std_benchmark.html
(the future)
--
Er is zon buiten. Zonnige zondag namiddag met priemgetallen in de plaats 
van buiten zitten. Tss tss. :-)

Re: speeding up + ctfe question

2012-05-27 Thread maarten van damme 
thank you :)

I wrote a sieve of aristotle because atkin's sieve needed waay to many
optimizations to beat aristotle's sieve by even a little bit so I
wanted to see if aristotle's was good enough.

I ran in two problems. It was extremely fast when sieving a byte array
of 1 million entries (without optimizations at all) but when trying
with 10_000_000 entries the program crashes before it even starts to
execute (main isn't reached).

Then I decided to benchmark the code and dmd fails to compile with
"Internal error: ..\ztc\cgcs.s 354".

I assume the first problem has to do with memory limits and that the
second is a little dmd bug. code is at
http://dl.dropbox.com/u/15024434/d/aristotleSieve.d

Re: speeding up + ctfe question

2012-05-27 Thread sclytrack 

On 05/27/2012 01:18 PM, maarten van damme wrote:

well, maybe, looking back at it, a range isn't the ideal way to go
about generating primes easily. I'm going to implement the sieve of
Atkin and make it return an array of primes up to a given number. This
might be a bit more useful and fast.

Is there somewhere I can catch up on ctfe? after reading andrei's book
and the documentation it's still not clear to me how I could make my
setquicktestsize function run at compile time.


https://github.com/PhilippeSigaud/D-templates-tutorial

Re: speeding up + ctfe question

2012-05-27 Thread maarten van damme 
well, maybe, looking back at it, a range isn't the ideal way to go
about generating primes easily. I'm going to implement the sieve of
Atkin and make it return an array of primes up to a given number. This
might be a bit more useful and fast.

Is there somewhere I can catch up on ctfe? after reading andrei's book
and the documentation it's still not clear to me how I could make my
setquicktestsize function run at compile time.

Re: speeding up + ctfe question

2012-05-26 Thread jerro 

On Saturday, 26 May 2012 at 18:40:53 UTC, maarten van damme wrote:
well, I was thinking about using a sieve but when you were to 
request

prime 400_000 you're sieve would blow up in size.


Because you only need primes up to sqrt(n) to check if n is prime,
you can make a sieve based range that only uses O(sqrt(n)) memory.
I've put an example at https://gist.github.com/2795954 .It could
be optimized further (skipping even numbers, keeping track of the
multiples of small primes...), but it is already much faster
than a range that does not use a sieve.


That's why I
opted
for something else (and I don't know if it was the right thing 
to do
though). (Ab)using opIndex like that is indeed a bit wrong but 
what

would be the alternative? remove slicing and introduce getPrime?
Wouldn't that be the same but without the great syntactic sugar?


Syntax sugar isn't great if it confuses people and causes bugs.
You can use r.drop(n).front to get nth element of a range.
If you need to do it often, you could just write a nth() function.

Re: speeding up + ctfe question

2012-05-26 Thread maarten van damme 
well, I was thinking about using a sieve but when you were to request
prime 400_000 you're sieve would blow up in size. That's why I opted
for something else (and I don't know if it was the right thing to do
though). (Ab)using opIndex like that is indeed a bit wrong but what
would be the alternative? remove slicing and introduce getPrime?
Wouldn't that be the same but without the great syntactic sugar?

Re: speeding up + ctfe question

2012-05-26 Thread jerro 

On Saturday, 26 May 2012 at 13:49:53 UTC, maarten van damme wrote:

Is there an easy way to speed up or is this the

ceiling?


I got a 30 percent speedup by replacing this line:

if(&& canFind(quicktestPrimes, possiblePrime))

with this:

if(quicktestPrimes.back >= possiblePrime &&
   canFind(quicktestPrimes, possiblePrime))

You could probably get a much better speedup by using some
kind of a prime sieve.

BTW you shouldn't be using opIndex like that. Calling opIndex
shouldn't change observable state of the object and it should
run in O(log(n)) or better. People expect an index operator to
behave similarly to the index operator on arrays. If the
function does something completely different, it is very
confusing to make it an opIndex.

Re: speeding up + ctfe question

2012-05-26 Thread sclytrack 

On 05/26/2012 03:49 PM, maarten van damme wrote:

I finally made the primerange I wanted to make. I think I'm using a
rather dumb algorithm. The idea is to store the prime we're at in
curPrime and the amount of preceding primes in countPrime. Then
opindex is able to calculate how many primes following or preceding
curPrime we have to find to get the asked value.
I'm not english so some names can be poorly chosen. Code is at
http://dl.dropbox.com/u/15024434/d/primeRange.d

The problem is that it's pretty slow. I wanted to find the first prime
number with 10 digits and it literally takes forever (but manages it
though). Is there an easy way to speed up or is this the ceiling?
(better algorithms, stupidity's I've left,...)

I also have an array of primes I use to "quicktest" to see if
something is a prime. You can change it's size using setQuicktestSize
at runtime. I want to make it large at compile time though. as I'm new
to ctfe I have no idea as to how one can do this.




See below for a rather dumb algorithm. The idea is to list
a list of prime numbers. The problem is that it is pretty
slow and you get a ...

//src/main.d(57): Error: template instance main.isDivisable!(499,498) 
recursive expansion


error when the number is too large. I'm not English so
the names ARE poorly chosen.


//writeln(primeList!(200)); //<---don't pick over 200 or it goes nuts
//writeln(decompose!(49,2));


template primeList(int index)
{
  static if (index > 1)
  {
static if (isPrime!(index))
{
  enum int [] primeList =  primeList!(index-1) ~ [index];
} else
{
  enum int [] primeList = primeList!(index-1);
}
  }
  else
  {
enum int [] primeList = [];
  }
}

template isDivisable( int number, int divisor)
{
  enum bool isDivisable = (number % divisor) == 0;
}
//  10 ---> [2,5]

template decompose(int number, int d = 2)
{
  static if (d < number)
  {
static if (isDivisable!(number, d))
{
  enum int [] decompose = [d] ~ decompose!(number/d, d);
}
else
{
  enum int [] decompose = decompose!(number, d+1);
}
  } else
  {
enum int [] decompose = [number];
  }
}

template isPrimeDecompose(int number, int d = 2)
{
  static if (d < number)
  {
static if (isDivisable!(number, d))
{
  enum bool isPrimeDecompose = false;
} else
{
  enum bool isPrimeDecompose = isPrimeDecompose!(number, d+1);
}
  } else
  {
enum bool isPrimeDecompose = true;
  }
}

template isPrime(int number)
{
  static if (number > 1)
   enum bool isPrime = isPrimeDecompose!(number, 2);
  else
   enum bool isPrime = false;
}

speeding up + ctfe question

2012-05-26 Thread maarten van damme 
I finally made the primerange I wanted to make. I think I'm using a
rather dumb algorithm. The idea is to store the prime we're at in
curPrime and the amount of preceding primes in countPrime. Then
opindex is able to calculate how many primes following or preceding
curPrime we have to find to get the asked value.
I'm not english so some names can be poorly chosen. Code is at
http://dl.dropbox.com/u/15024434/d/primeRange.d

The problem is that it's pretty slow. I wanted to find the first prime
number with 10 digits and it literally takes forever (but manages it
though). Is there an easy way to speed up or is this the ceiling?
(better algorithms, stupidity's I've left,...)

I also have an array of primes I use to "quicktest" to see if
something is a prime. You can change it's size using setQuicktestSize
at runtime. I want to make it large at compile time though. as I'm new
to ctfe I have no idea as to how one can do this.