Proposal: System.Timeout module for base

[Peter Simons]

Hi David,

let's agree to disagree. Apparently our personal preferences
differ when it comes to error handling.

Regarding the submission of 'timeout', I feel that those two
lines say it all:

  timeout n f >>= maybe (fail "timeout") return

  (Just `fmap` timeout n t) `catch` (\_ -> return Nothing)

An exception-throwing timeout combinator is obviously equivalent
to one that returns "Maybe a" because both versions can be
trivially wrapped to behave like the other one.

I am in favor of using the version we have.

Best regards,
Peter