special handling of "Main.hs" contradicts Report

[Dean Herington]

Ross Paterson wrote:

> On Fri, Apr 25, 2003 at 09:51:55AM +0100, Simon Marlow wrote:
> > [Mark Tullsen <mtullsen at cse.ogi.edu> writes:]
> > >   The report leads one to believe "module Main where ..."
> > > should export
> > >   all top-level entitities just the same as if we were
> > > defining a module by another name.
> >
> > Yes, we're aware this is a bug (see my first message in this thread).
> > However, I think we're going to declare it as a known
> > divergence from the report, for two reasons:
> >
> >   - It's highly unlikely that you need to import Main, so
> >     you'll never notice the difference.  If you *do* need more
> >     exports from Main, then write 'module Main(module Main) where'.
>
> I expect it would be confusing for GHCi users.
>
> >   - interpreting 'module Main where' as 'module Main(main) where'
> >     leads to more efficient code (we have lots of examples
> >     that do this, I believe).
>
> How about just suggesting that users write 'module Main(main) where'
> to get more efficient code?

I second Ross's opinions.  Here's a situation that I just encountered that
argues for his approach.

I'm developing a program.  I usually compile it (using `ghc`) after making
changes, so I can run some batch tests.  Sometimes I want to do some
interactive exploration, in which case I invoke `ghci` on it.  Without the
artificial `module Main (module Main) where`, ghci sees none of the
top-level entities in the main module in its compiled form.  I have to
artificially change the source file and :reload to see these entities.

Dean