Error accessing data files from package code in Cabal: Unkown symbol

Alfonso Acosta

1 Jul 2008 1 Jul '08

2:19 p.m.

Hi! I'm working on a library package called ForSyDe. Following Cabal's documentation, I'm using the autogenerated Paths_ForSyDe module in order to access the data files of my library during execution. After installation, the Paths_ForSyDe import seems to be causing an unknown-symbol error whenever I try to compile any code which makes use of the ForSyDe library: " unknown symbol `___stginit_ForSyDezm0zi1_PathszuForSyDe_' " I'm not sure, but it seems that cabal doesn't properly link or install the Paths_ForSyDe module (I tried to include it in the cabal description file to no avail) Any suggestions about how to fix this problem? Thanks in advance, Fons P.S: I'm using Cabal-1.2.3.0

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Don Stewart

1 Jul 1 Jul

2:26 p.m.

New subject: Error accessing data files from package code in Cabal: Unkown symbol

alfonso.acosta:

...

Hi!

I'm working on a library package called ForSyDe.

Following Cabal's documentation, I'm using the autogenerated Paths_ForSyDe module in order to access the data files of my library during execution.

After installation, the Paths_ForSyDe import seems to be causing an unknown-symbol error whenever I try to compile any code which makes use of the ForSyDe library:

" unknown symbol `___stginit_ForSyDezm0zi1_PathszuForSyDe_' "

I'm not sure, but it seems that cabal doesn't properly link or install the Paths_ForSyDe module (I tried to include it in the cabal description file to no avail)

Any suggestions about how to fix this problem?

Thanks in advance,

Probably you've not listed the Paths_ForSyDe module in your module exports in the .cabal file?

Alfonso Acosta

3:10 p.m.

New subject: Error accessing data files from package code in Cabal: Unkown symbol

On Tue, Jul 1, 2008 at 1:26 PM, Don Stewart wrote:

...

Probably you've not listed the Paths_ForSyDe module in your module exports in the .cabal file?

Thanks, that was the problem. Since Paths_pkgname is somehow a special module, I stupidly assumed that cabal would take care of exporting it under the hood. I hope that the directory where the Paths_pkgname is included (dist/build/autogen ) doesn't change in the future. Either way, I think it would be a good idea to include a comment about it in the Cabal documentation (http://www.haskell.org/cabal/release/latest/doc/users-guide/authors.html#pat... ).

Duncan Coutts

2 Jul 2 Jul

9:57 a.m.

New subject: Error accessing data files from package code in Cabal: Unkown symbol

On Tue, 2008-07-01 at 14:10 -0500, Alfonso Acosta wrote:

...

On Tue, Jul 1, 2008 at 1:26 PM, Don Stewart wrote:

...
Probably you've not listed the Paths_ForSyDe module in your module exports in the .cabal file?

Thanks, that was the problem.

Since Paths_pkgname is somehow a special module, I stupidly assumed that cabal would take care of exporting it under the hood. I hope that the directory where the Paths_pkgname is included (dist/build/autogen ) doesn't change in the future.

Do not hard code the path. It can change (via a command line flag). It's not necessary to hard code anything anyway, just using: other-modules: Paths_ForSyDe will work fine (because the $dist/build/autogen path is on the sources search path) I suggest using other-modules rather than exposed-modules because you probably do not need to make that module part of your public api.

...

Either way, I think it would be a good idea to include a comment about it in the Cabal documentation (http://www.haskell.org/cabal/release/latest/doc/users-guide/authors.html#pat... ).

Right. Duncan

Alfonso Acosta

11:50 a.m.

New subject: Error accessing data files from package code in Cabal: Unkown symbol

On Wed, Jul 2, 2008 at 8:57 AM, Duncan Coutts wrote:

...

Do not hard code the path. It can change (via a command line flag).

It's not necessary to hard code anything anyway, just using:

other-modules: Paths_ForSyDe

I tried to avoid doing it, but without adding dist/build/autogen to hs-source-dirs (that is, leaving it as "hs-source-dirs: src") I get the following error: Setup.hs: can't find source for Paths_ForSyDe in ["src"]

...

I suggest using other-modules rather than exposed-modules because you probably do not need to make that module part of your public api.

Yes, that's what I did.

Duncan Coutts

12:17 p.m.

New subject: Error accessing data files from package code in Cabal: Unkown symbol

On Wed, 2008-07-02 at 10:50 -0500, Alfonso Acosta wrote:

...

On Wed, Jul 2, 2008 at 8:57 AM, Duncan Coutts wrote:

...
Do not hard code the path. It can change (via a command line flag).

It's not necessary to hard code anything anyway, just using:

other-modules: Paths_ForSyDe

I tried to avoid doing it, but without adding dist/build/autogen to hs-source-dirs (that is, leaving it as "hs-source-dirs: src") I get the following error:

Setup.hs: can't find source for Paths_ForSyDe in ["src"]

Ah, sorry, that bug was only fixed in Cabal-1.4 so yes it will not work in Cabal-1.2.x. The reason not that many people have run into this issue is that typically it is executables not libraries that use data files and thus use the Paths_pkgname module and for executables it's possible to get away without listing all modules in the extra/other-modules fields. Duncan

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Alfonso Acosta
Don Stewart
Duncan Coutts