Hiding non-existent entities

[Simon Peyton-Jones]

Simon and Manuel propose that it should be an error for an
import statement to hide something which isn't exported by
the module being imported.

This is a point on which I am willing to be swayed.
It's a matter of taste, and really it doesn't matter what
we decide provided we decide something.

I'll adopt Simon & Manuel's view unless enough people yell.
Frankly, I don't think it is worth a hullabaloo.

Simon

| -----Original Message-----
| From: Manuel M. T. Chakravarty [mailto:chak@cse.unsw.edu.au]=20
| Sent: 30 August 2001 07:20
| To: Simon Marlow
| Cc: haskell@haskell.org
| Subject: Re: Hiding non-existent entities
|=20
|=20
| "Simon Marlow" <simonmar@microsoft.com> wrote,
|=20
| > The Haskell 98 errata page currently contains this item=20
| related to a=20
| > hiding clause on an import declaration which refers to a=20
| non-existent
| > entity:
| >=20
| >   [Aug 2001] Page 66, Section 5.3, Import Declarations,
| >   numbered item 2. Add "It is not an error to hide an entity
| >   that is not, in fact, exported by the imported module, although
| >   compilers are encouraged to flag a warning in this case." (This
| >   is different from what I proposed by email, which made this case
| >   an error, but it allow a bit more flexibility as modules change.)
| >=20
| > IMO allowing a hiding clause to refer to a non-existent entity is a=20
| > bit odd.  Haskell doesn't have any other features like this: it's=20
| > always an error to refer to an entity that isn't defined anywhere,=20
| > even if the reference is otherwise harmless.  Does anyone else have=20
| > any opinions on this?
|=20
| I agree with you.
|=20
| Cheers,
| Manuel
|=20
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