On Jun 11, 2010, at 5:10 AM, Brandon S. Allbery KF8NH wrote: <snip>
This doesn't surprise me; when putting it in the module, it affects only that module. When using either command line version, it affects *everything*... and what's breaking is not your definition of Number, but the ghci expression printer (which, being in IO, is doing something like (print it >> putStr "\n"). Since the command line option has global effect, the Prelude's (>>) isn't defined for ghci's guts either.
Your explanation would make perfect sense to me; pragma's in the module effect only the module. This is, however, nog GHCi's behaviour. If I have a module that's only this: {-# LANGUAGE NoImplicitPrelude #-} module Foo where and I open this in GHCi, I get the following session: Ok, modules loaded: Foo. *Foo> 42 42 *Foo> 42.0 42.0 *Foo> :t 42 42 :: (GHC.Num.Num t) => t *Foo> 40 + 2 <interactive>:1:3: Not in scope: `+' *Foo> :t fromRational <interactive>:1:0: Not in scope: `fromRational' *Foo> This means that there is *some* definition of fromInteger, fromRational and (>>), but it's not accessible for me at the prompt. Types and typeclasses seem to be imported fully qualified. I would either expect GHCi to start complaining when I type 42, or to not complain about any of these above commands. Any thoughts? Regards, Philip