Hi.

Should the following code work?

import std.bitmanip;
import std.stdio;
import std.array;
import std.range:chain;

void test()
{
	int[] a=[1,2,3,4,5];
	int[] b=[5,4,3,2,1];
	int[] c = chain(a,b).array; // chain two arrays of int
	writefln("%s",c);
}

void test2()
{
	BitArray a;
	a.init([1,0,1,0]);
	BitArray b;
	b.init([0,1,0,1]);
	BitArray[] d;
	d~=a;
	d~=b;
	BitArray[] c=chain([a],[b]).array; // cannot chain two bitarrays
	BitArray[] e=chain(d,d).array; // cannot chain two arrays of bitarrays
	writefln("%s",c);
}

int main(string[] args)
{
	test();
	test2();
	return 1;
}

bitmanip.d(23): Error: template std.range.chain cannot deduce function from argument types !()(BitArray, BitArray), candidates are:
/usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))
bitmanip.d(24): Error: template std.range.chain cannot deduce function from argument types !()(BitArray[], BitArray[]), candidates are:
/usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))
bitmanip.d(24): Error: declaration bitmanip.test2.c is already defined
bitmanip.d(25): Error: template std.range.chain cannot deduce function from argument types !()(BitArray[], BitArray[]), candidates are:
/usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))

I cannot seem to concatenate - directly, or using chain - two bitarrays, or two arrays of bitarrays.

To avoid confusion, the below is the code that fits the error message:

import std.bitmanip;
import std.stdio;
import std.array;
import std.range:chain;

void test()
{
	int[] a=[1,2,3,4,5];
	int[] b=[5,4,3,2,1];
	int[] c = chain(a,b).array; // chain two arrays of int
	writefln("%s",c);
}

void test2()
{
	BitArray a;
	a.init([1,0,1,0]);
	BitArray b;
	b.init([0,1,0,1]);
	BitArray[] d;
	d~=a;
	d~=b;
	BitArray[] c=chain(a,b).array; // cannot chain two bitarrays
	BitArray[] c=chain([a],[b]).array; // cannot chain two bitarrays
	BitArray[] e=chain(d,d).array; // cannot chain two arrays of bitarrays
	writefln("%s",c);
}

int main(string[] args)
{
	test();
	test2();
	return 1;
}

On Saturday, 24 January 2015 at 00:13:34 UTC, Laeeth Isharc wrote:
> Hi.
>
> Should the following code work?
>

Yes, that error is caused by a bug of BitArray(https://issues.dlang.org/show_bug.cgi?id=13806). Having "init" function broke template constraints of "chain"(and must break dozen of other templates).

pragma(msg, ElementType!(BitArray[])) // prints 'pure nothrow void(bool[] ba)' - ElementType uses "init" property to determine types.

> import std.bitmanip;
> import std.stdio;
> import std.array;
> import std.range:chain;
>
> void test()
> {
> 	int[] a=[1,2,3,4,5];
> 	int[] b=[5,4,3,2,1];
> 	int[] c = chain(a,b).array; // chain two arrays of int
> 	writefln("%s",c);
> }
>
> void test2()
> {
> 	BitArray a;
> 	a.init([1,0,1,0]);
> 	BitArray b;
> 	b.init([0,1,0,1]);
> 	BitArray[] d;
> 	d~=a;
> 	d~=b;
> 	BitArray[] c=chain([a],[b]).array; // cannot chain two bitarrays
> 	BitArray[] e=chain(d,d).array; // cannot chain two arrays of bitarrays
> 	writefln("%s",c);
> }
>
> int main(string[] args)
> {
> 	test();
> 	test2();
> 	return 1;
> }
>
> bitmanip.d(23): Error: template std.range.chain cannot deduce function from argument types !()(BitArray, BitArray), candidates are:
> /usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))
> bitmanip.d(24): Error: template std.range.chain cannot deduce function from argument types !()(BitArray[], BitArray[]), candidates are:
> /usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))
> bitmanip.d(24): Error: declaration bitmanip.test2.c is already defined
> bitmanip.d(25): Error: template std.range.chain cannot deduce function from argument types !()(BitArray[], BitArray[]), candidates are:
> /usr/include/dmd/phobos/std/range.d(2493):        std.range.chain(Ranges...)(Ranges rs) if (Ranges.length > 0 && allSatisfy!(isInputRange, staticMap!(Unqual, Ranges)) && !is(CommonType!(staticMap!(ElementType, staticMap!(Unqual, Ranges))) == void))
>
> I cannot seem to concatenate - directly, or using chain - two bitarrays, or two arrays of bitarrays.

> Yes, that error is caused by a bug of BitArray(https://issues.dlang.org/show_bug.cgi?id=13806). Having "init" function broke template constraints of "chain"(and must break dozen of other templates).
>
> pragma(msg, ElementType!(BitArray[])) // prints 'pure nothrow void(bool[] ba)' - ElementType uses "init" property to determine types.


Thanks for this.  If I recompile phobos with the pull request (having edited out the init property entirely) then the code mostly works.

However, I still can't use join, joiner, or chain on two BitArrays.  Eg
auto x=joiner(a,b).array;

I can chain two arrays of BitArrays, but not join or joiner them.

If this is what ought to happen, why?