I'm curious to why we need std.range.equal in cases such as

bool isPalindrome(Range)(in Range range) if (isBidirectionalRange!Range)
{
    return range.retro.equal(range);
}

Why isn't equality == operator used here instead?

/Per

Per Nordlöw:

> Why isn't equality == operator used here instead?

In some cases I'd even like to use ~ instead of chain().

Bye,
bearophile

On Tuesday, 18 February 2014 at 09:31:55 UTC, Per Nordlöw wrote:
> I'm curious to why we need std.range.equal in cases such as
>
> bool isPalindrome(Range)(in Range range) if (isBidirectionalRange!Range)
> {
>     return range.retro.equal(range);
> }
>
> Why isn't equality == operator used here instead?
>
> /Per

1) opEquals cannot be a free function
2) there's no telling what opEquals does if Range defines it

IOW, equal() has a defined by-element-comparison semantics, while opEquals doesn't.

On Tuesday, 18 February 2014 at 09:34:41 UTC, bearophile wrote:

> In some cases I'd even like to use ~ instead of chain().

Range interface should be minimal. Don't forget that user types can provide range interface and still benefit from operator overloading for different purposes.

Stanislav Blinov:

> Range interface should be minimal.

I agree. But I didn't mean to ask for that operator in the Range protocol. I think some ranges should define a ~ operator. It's easy to write a "chainable" trait. I did that for my nonstandard D1 library.

Bye,
bearophile

On Tuesday, 18 February 2014 at 10:47:33 UTC, bearophile wrote:
> Stanislav Blinov:
>
>> Range interface should be minimal.
>
> I agree. But I didn't mean to ask for that operator in the Range protocol. I think some ranges should define a ~ operator. It's easy to write a "chainable" trait. I did that for my nonstandard D1 library.
>
> Bye,
> bearophile

Could you post the isChainable trait?

I'm curious :)

/Per

On Tuesday, 18 February 2014 at 11:39:12 UTC, Per Nordlöw wrote:
> On Tuesday, 18 February 2014 at 10:47:33 UTC, bearophile wrote:
>> Stanislav Blinov:
>>
>>> Range interface should be minimal.
>>
>> I agree. But I didn't mean to ask for that operator in the Range protocol. I think some ranges should define a ~ operator. It's easy to write a "chainable" trait. I did that for my nonstandard D1 library.
>>
>> Bye,
>> bearophile
>
> Could you post the isChainable trait?
>
> I'm curious :)
>
> /Per

Ahh, I guess you mean

http://forum.dlang.org/thread/bug-6043-3@http.d.puremagic.com%2Fissues%2F

/Per