Abstract FilePath Proposal

[Henning Thielemann]

On Sat, 27 Jun 2015, David Fox wrote:

> ​I've had success with a slightly different "How":
> 
> Phase 1: Replace FilePath with a type class, with instances for the old 
> FilePath (i.e. String) and the new implementation.

There could be more instances for platform specific FilePath types, e.g. 
for creating Windows file paths on Unix.