Adding Fixed Point Data Types to base

[Henning Thielemann]

On Sun, 16 Oct 2016, Andrew Martin wrote:

> Thanks for weighing in. It is possible to use cabal flags + CPP to work 
> around this, although I don't like doing that for the reasons you would 
> expect. I'm also not typically comfortable opening up an issue to ask a 
> package maintainer to add a flag to enable conditional dependencies for 
> instances.

Conditionally compiling instances into a package is not an option. If 
another package imports a certain version of your package it can expect 
the availability of all instances. There is no other way for a package to 
assert certain instances other than specifying the package version.