Equality of `pred` Template Parameters

[via Digitalmars-d]

In https://github.com/D-Programming-Language/phobos/pull/3534
I'm in need of a generic and correct definition of

    template isSortedRange(T, alias pred = "a < b")

at

https://github.com/D-Programming-Language/phobos/pull/3534/files#diff-9f63c74383984a09f5bf578493892e27R1005

To make it general we want it to support `pred` argument of types 
other than `string`, typically

    binaryFun!"a < b"

Specifically, we want `isSortedRange` to "understand" that

    binaryFun!"a < b"
    binaryFun!"a<b"

are equvialent and

    binaryFun!"a < b"
    binaryFun!"a > b"

are not (opposites). I'm guessing there is compile-time-parsing 
somewhere in Phobos that already does this. Could/Should this be 
extracted and reused?

Destroy!