Re: The dreaded M-R

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... Thanks Neil