3 release policy

[Henning Thielemann]

On Tue, 20 Oct 2015, Jeremy wrote:

> A "3 release policy" has been recently mentioned several times, whereby it
> should always be possible to write code that compiles with the last three
> releases of GHC, without generating any -Wall warnings.
>
> The no warning requirement seems excessively harsh.

If you accept warnings in your code you always have to check which 
warnings are relevant and which ones you want to react on. Checking for no 
warnings is much simpler.

Actually, I don't pay attention to GHC-7.10 warnings anymore because there 
are so many irrelevant duplicate import warnings. I am not using GHC-7.10 
seriously, it has this intermediate flavour (also because of the type 
family problem I mentioned earlier). Thus the 3 release policy for me is 
already only a "2 usable releases policy".

Btw. I use every LTS version of Ubuntu full 4 years. 2 years is still too 
frequent change for me.