On Mon, Feb 2, 2015 at 12:46 PM, Jochen Keil wrote:

Hello Peter,

On 02.02.2015 12:31, Peter Simons wrote:

...

Hi Jochen,

...

My main goal would be to have a program which takes two modules of different versions, compare them and highlight the differences between them.

maybe http://hackage.haskell.org/package/hackage-diff would work for your purposes?

Thanks for the hint, this looks pretty good.

One thing though: hackage-diff uses haskell-src-exts for parsing modules. Does haskell-src-exts re-use the GHC API or does it run its own parser? (from a quick glance I'd say the latter case)

There are basically two routes to choose from with such a tool (of which a few already exist, I think): you can use GHC and its API, like you're doing, or you can use haskell-src-exts, which is a separate parser, and use haskell-names for name resolution (and haskell-packages for dependency information). Sadly there's no haskell-type-exts for typechecking (yet). The GHC route is probably more powerful, the haskell-suite route is simpler and doesn't depend on GHC. Regards, Erik

Hi Erik, On 02.02.2015 12:55, Erik Hesselink wrote:

On Mon, Feb 2, 2015 at 12:46 PM, Jochen Keil wrote:

...

Hello Peter,

On 02.02.2015 12:31, Peter Simons wrote:

...

Hi Jochen,

...

My main goal would be to have a program which takes two modules of different versions, compare them and highlight the differences between them.

maybe http://hackage.haskell.org/package/hackage-diff would work for your purposes?

Thanks for the hint, this looks pretty good.

One thing though: hackage-diff uses haskell-src-exts for parsing modules. Does haskell-src-exts re-use the GHC API or does it run its own parser? (from a quick glance I'd say the latter case)

There are basically two routes to choose from with such a tool (of which a few already exist, I think): you can use GHC and its API, like you're doing, or you can use haskell-src-exts, which is a separate parser, and use haskell-names for name resolution (and haskell-packages for dependency information). Sadly there's no haskell-type-exts for typechecking (yet). The GHC route is probably more powerful, the haskell-suite route is simpler and doesn't depend on GHC.

thanks for the clarification! Indeed it seems to me that the GHC approach is more powerful, because after running the typechecker I would have the AST available for comparing modules (did I get this right?). Drawback would obviously be the need for running the typechecker. :) So, just for the sake of my curiosity: Is there a way to get the exported declarations (and not just the RdrNames) from GHC without running the typechecker? I don't understand why it's necessary to run the typechecker in order to get this list. The parser already returns a list with all declarations, so shouldn't it be possible to filter this list for only the exported ones? Thanks, Jochen

Hi, On 02.02.2015 18:36, Alan & Kim Zimmerman wrote:

Have you looked at ModuleInfo [1] ?

Yes, that's the path I went after type checking the module. There's also ModIface which could be suitable for my purpose.

And what do you mean by the exported declarations?

I'm sorry if I didn't make my intent clear enough. There's the pure parser [1], which (at least I think so) is also used for parseModule [2]. This results in a HsModule object [3]. HsModule provides amongst others a field for exports [4] and *all* declarations [5]. I am explicitly only interested in *exported declarations*. But I don't see how I could combine [4] and [5] to achieve that, while avoiding to run the type checker. Sorry again if I was or still am unclear, but I hope it's better now. :) Cheers, Jochen [1] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/GHC.h... [2] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/GHC.h... [3] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/HsSyn... [4] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/HsSyn... [5] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/HsSyn...

If you are prepared to use the HaRe API (ony up to GHC 7.6.3) you can use definingDeclsNames [2]

[1] https://downloads.haskell.org/~ghc/7.8.3/docs/html/libraries/ghc-7.8.3/GHC.h... [2] http://hackage.haskell.org/package/HaRe-0.7.2.8/docs/Language-Haskell-Refact...

On Mon, Feb 2, 2015 at 6:58 PM, Jochen Keil wrote:

...

Hi Erik,

On 02.02.2015 12:55, Erik Hesselink wrote:

...

On Mon, Feb 2, 2015 at 12:46 PM, Jochen Keil wrote:

...

Hello Peter,

On 02.02.2015 12:31, Peter Simons wrote:

...

Hi Jochen,

...

My main goal would be to have a program which takes two modules of different versions, compare them and highlight the differences between them.

maybe http://hackage.haskell.org/package/hackage-diff would work for your purposes?

Thanks for the hint, this looks pretty good.

One thing though: hackage-diff uses haskell-src-exts for parsing modules. Does haskell-src-exts re-use the GHC API or does it run its own parser? (from a quick glance I'd say the latter case)

There are basically two routes to choose from with such a tool (of which a few already exist, I think): you can use GHC and its API, like you're doing, or you can use haskell-src-exts, which is a separate parser, and use haskell-names for name resolution (and haskell-packages for dependency information). Sadly there's no haskell-type-exts for typechecking (yet). The GHC route is probably more powerful, the haskell-suite route is simpler and doesn't depend on GHC.

thanks for the clarification! Indeed it seems to me that the GHC approach is more powerful, because after running the typechecker I would have the AST available for comparing modules (did I get this right?). Drawback would obviously be the need for running the typechecker. :)

So, just for the sake of my curiosity: Is there a way to get the exported declarations (and not just the RdrNames) from GHC without running the typechecker? I don't understand why it's necessary to run the typechecker in order to get this list. The parser already returns a list with all declarations, so shouldn't it be possible to filter this list for only the exported ones?

Thanks, Jochen

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