Type-specific overloads in Phobos

[Joseph Rushton Wakeling]

Hello all,

There are various generic functions in Phobos that can benefit from 
type-specific overloads.  For example, in std.math and std.numeric, functions 
that deal with integers may benefit from having specialized implementations to 
work with BigInt.

Question: what's the appropriate location for these overloads?  In the same 
module as their type, or in the same module as the function they're overloading? 
  What are the implications for correct inferring of what function to use, or 
useful aliases (e.g. alias abs = std.math.abs)?

Thanks & best wishes,

     -- Joe