Re: Trying Multiple Aggregate reduce

2014-04-02 Thread monarch_dodra 

On Monday, 31 March 2014 at 22:25:40 UTC, Nordlöw wrote:

You can't use reduce with a const seed.



This, surely, must be a compiler bug right?

/Per


Arguably, it's a user bug ;) The user should have provided a 
non-const seed.


*But*, there have been many cases of reduce being made to accept 
const seeds before, via unqualified copy. This case must have 
just been a missed one.


In any case, I had submitted a re-write for reduce, and it just 
so happens to support this. So I added your code to the test 
cases:

https://github.com/D-Programming-Language/phobos/pull/2060

Re: Trying Multiple Aggregate reduce

2014-04-02 Thread Nordlöw 
so happens to support this. So I added your code to the test 
cases:


Great!

BTW: Why is static qualifier needed on definition of 
minmaxElement() in the unittest?

Re: Trying Multiple Aggregate reduce

2014-04-02 Thread monarch_dodra 

On Wednesday, 2 April 2014 at 09:25:53 UTC, Nordlöw wrote:
so happens to support this. So I added your code to the test 
cases:


Great!

BTW: Why is static qualifier needed on definition of 
minmaxElement() in the unittest?


Whenever you declare something in a nested context, it may or may 
not have a hidden context pointer, depending on the type, and the 
implementation.


static, in this context, ensures this does not happen. It's not 
actually *needed* in this context though. It's more of a matter 
of style.


In your example, the function was declared in global context, so 
the static would have been gratuitous.

Trying Multiple Aggregate reduce

2014-03-31 Thread Nordlöw 

I'm trying to figure out how to use reduce with multiply funs.

Here's my try on minmaxElement:


import std.typecons: tuple;

/** Returns: Tuple of Minmum and Maximum Element in X. */
auto minmaxElement(alias F = min, alias G = max, R)(in R range)
@safe pure nothrow if (isInputRange!R)
{
return reduce!(F, G)(tuple(ElementType!R.max,
   ElementType!R.min), range);
}

unittest { assert([1, 2, 3].minmaxElement == tuple(1, 3)); }


which errors as

/home/per/opt/x86_64-unknown-linux-gnu/dmd/bin/../include/d2/std/algorithm.d(774,29): 
Error: can only initialize const member _expand_field_0 inside 
constructor
/home/per/opt/x86_64-unknown-linux-gnu/dmd/bin/../include/d2/std/algorithm.d(774,29): 
Error: can only initialize const member _expand_field_1 inside 
constructor
algorithm_ex.d(157,25): Error: template instance 
std.algorithm.reduce!(min, max).reduce!(Tuple!(const(int), 
const(int)), const(int)[]) error instantiating
algorithm_ex.d(160,28):instantiated from here: 
minmaxElement!(min, max, const(int)[])



If I replace ElementType!R.min and ElementType!R.max with a 
values, say 0 and 1 it compiles. What is going on here?


This seems related:
http://forum.dlang.org/thread/bug-1040...@http.d.puremagic.com/issues/

Re: Trying Multiple Aggregate reduce

2014-03-31 Thread bearophile 

Nordlöw:


I'm trying to figure out how to use reduce with multiply funs.


import std.algorithm: min, max, reduce;
import std.typecons: tuple, Unqual;
import std.range: isInputRange, ElementType;

/// Returns: Tuple of Minmum and Maximum Element in X.
auto minMax(alias F = min, alias G = max, R)(in R range)
@safe pure nothrow if (isInputRange!R) {
return reduce!(F, G)(tuple(Unqual!(ElementType!R).max,
   Unqual!(ElementType!R).min), 
range);

}

unittest {
assert([1, 2, 3].minMax == tuple(1, 3));
}

void main() {}


If I replace ElementType!R.min and ElementType!R.max with a 
values, say 0 and 1 it compiles. What is going on here?


This seems related:
http://forum.dlang.org/thread/bug-1040...@http.d.puremagic.com/issues/


You can't use reduce with a const seed.

Bye,
bearophile

Re: Trying Multiple Aggregate reduce

2014-03-31 Thread Ali Çehreli 

On 03/31/2014 03:13 PM, bearophile wrote:

Nordlöw:


I'm trying to figure out how to use reduce with multiply funs.


Could someone please check the following. It looks like a compiler bug 
on git head (DMD64 D Compiler v2.066-devel-75159e4):


import std.algorithm;

int foo(int value)
{
return value;
}

void main()
{
reduce!(foo, foo)(tuple(0, 0), [ 1 ]);
}

statement.c:274: ErrorStatement::ErrorStatement(): Assertion 
`global.gaggedErrors || global.errors' failed.


Ali

Re: Trying Multiple Aggregate reduce

2014-03-31 Thread Nordlöw 

You can't use reduce with a const seed.



This, surely, must be a compiler bug right?

/Per

Re: Trying Multiple Aggregate reduce

2014-03-31 Thread bearophile 

Ali Çehreli:

statement.c:274: ErrorStatement::ErrorStatement(): Assertion 
`global.gaggedErrors || global.errors' failed.


It's a little compiler bug, that should go in Bugzilla (even if 
perhaps it was recently added).


Bye,
bearophile

Re: Trying Multiple Aggregate reduce

2014-03-31 Thread Ali Çehreli 

On 03/31/2014 04:01 PM, bearophile wrote:

Ali Çehreli:


statement.c:274: ErrorStatement::ErrorStatement(): Assertion
`global.gaggedErrors || global.errors' failed.


It's a little compiler bug, that should go in Bugzilla (even if perhaps
it was recently added).


  https://d.puremagic.com/issues/show_bug.cgi?id=12501

Ali