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.