Re: Unused import warning on re-export

Actually, I just tried to make an example of this, and GHC does not seem to export `f`, just as the report says. So I'd say GHC is behaving correctly, both with the exports and the warning. On Fri, May 12, 2017 at 10:39 AM, Iavor Diatchki wrote:

Hello,

actually, the bug here is that `f` is exported, as omitting the export list is not equivalent to writing `module A` in the export list.

This is explicitly stated in Section 5.2 of the Haskell report:

"If the export list is omitted, all values, types and classes defined in the module are exported, but not those that are imported."

-Iavor

On Thu, May 11, 2017 at 1:23 PM, Simon Peyton Jones via Glasgow-haskell-users wrote:

...

| Is there a reason GHC considers this case an unused import? It seems that | the use of the import is explicitly stated right within the import | itself. Should I submit a ticket for this?

Hmm. I think you are saying that

module A where import B as A(f) g = True

that is equivalent to module A( module A ) where ...

which exports all things "x" in scope as "A.x". So it'll export both f and g.

But GHC will report f as unused, but not g. And that's inconsistent. Fair point. Yes, file a ticket. Better still, offer a patch :-).

Simon

| -----Original Message----- | From: Glasgow-haskell-users [mailto:glasgow-haskell-users- | bounces@haskell.org] On Behalf Of Yitzchak Gale | Sent: 10 May 2017 13:56 | To: GHC users | Subject: Unused import warning on re-export | | I have a module A with no export list, and a function f which from the | API point of view should part of the export list of A. But f must be | defined in module B, not module A, due an import cycle. I added this line | in module A to re-export f from A: | | import B as A (f) | | This resulted in an unused import warning. That is a problem for us - we | keep our large code base clean of warnings as a policy. | | Is there a reason GHC considers this case an unused import? It seems that | the use of the import is explicitly stated right within the import | itself. Should I submit a ticket for this? | | Thanks, | Yitz | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | https://na01.safelinks.protection.outlook.com/?url=http%3A% 2F%2Fmail.hask | ell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fglasgow-haskell- | users&data=02%7C01%7Csimonpj%40microsoft.com%7C81b06c9737d54 0a597df08d497 | a413d0%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63630017 8355700119&sd | ata=xHt1FXEF5r4WMaMF3FSW4jFBRlB4OK8DQdcNAxZ7HOc%3D&reserved=0 _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users