Andrew Pimlott wrote:
On Tue, Jan 31, 2006 at 12:52:51AM +0000, Neil Mitchell wrote:
Second, a warning about "loss of sharing" may befuddle beginners (who are usually not taught to write type signatures at the start).
Are standards documents the place for prescribing which warnings should be raised, and under what circumstances?
If someone is using GHC, and has specified -O2 then clearly something that causes vastly more time is a problem. If someone is learning Haskell and is using Hugs then they probably couldn't care less. Perhaps some warnings should be left up to the implementation to decide...
My ultimate point was that the possibility of a warning should carry very little weight (if any) when analyzing the pros and cons of a language change. If you want to argue that a warning would mitigate a disadvantage of a change, you need to think about when the warning would be emitted, which I agree should be outside the scope of a standards discussion. So I am just suggesting that we simplify the discussion by not talking about warnings (which suggestion I will follow as soon as I hit send!).
I agree that a requiring a warning in the language standard is a rather dodgy thing. So let's say we don't have a warning. Is this a tried solution? Yes, nhc does exactly that. It does not have the M-R nor a warning. And I have never heard outcries about how bad nhc is because of this. -- Lennart