Expressing range constraints in CNF form

[crimaniak via Digitalmars-d]

On Sunday, 11 June 2017 at 00:28:58 UTC, Andrei Alexandrescu 
wrote:
> enum bool isInputRange(R) =
>     is(typeof((ref R r) => r)) && "must be copyable"

Regardless of the implementation method, this will require the 
previously proposed Phobos refactoring. Independent special 
definitions have to be reduced to general ones and use "static 
if" to select the algorithm. Otherwise, each failed independent 
definition will give an additional error message, and the 
compiler does not have the ability to determine which one is 
relevant.