Phobos PR: `call` vs. `bindTo`

[Tofu Ninja via Digitalmars-d]

On Tuesday, 5 August 2014 at 19:31:08 UTC, H. S. Teoh via 
Digitalmars-d wrote:
> There are currently two Phobos PR's that implement essentially 
> the same
> functionality, but in slightly different ways:
>
> 	https://github.com/D-Programming-Language/phobos/pull/1255
> 	https://github.com/D-Programming-Language/phobos/pull/2343
>
>>From the discussion on Github, it seems to me that we should 
>>only
> introduce one new function rather than two similar but
> not-quite-the-same functions. Since the discussion seems stuck 
> on
> Github, I thought I should bring it here to the larger 
> community to see
> if we can reach a consensus (who am I kidding... but one can 
> hope :-P)
> on:
>
> (1) What name to use (bring on the bikeshed rainbow)
> (2) Exactly what functionality should be included.
> (3) Which PR to merge.
>
>
> T

Can you explain the utility of both of them? I am not big into 
functional programming so I am not seeing it.