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GHC API: modInfoIsExportedName, String -> Name?

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Daniel Trstenjak

19 Oct 2013 19 Oct '13

9:58 a.m.

Hi, I wanted to use the GHC API to find if a symbol is exported from a module. The function 'modInfoIsExportedName :: ModuleInfo -> Name -> Bool' seems to do what I want, but how do I convert a symbol string into a 'Name'? Thanks for any hints! Greetings, Daniel

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Dan Frumib

19 Oct 19 Oct

12:51 p.m.

Hi. Correct me if I am wrong, but you are not supposed to construct 'Name's yourself. The point is that they are unique and hiding the constructors is a step towards preserving the invariants. Here's how I would do something like 'map nameOccName . modInfoExports' and then search for an OccName (which you can construct using mkOccName). Unfortunately I don't have GHC handy so I can't test this Cheers - Dan

On 19 Oct 2013, at 17:58, Daniel Trstenjak wrote:

Hi,

I wanted to use the GHC API to find if a symbol is exported from a module.

The function 'modInfoIsExportedName :: ModuleInfo -> Name -> Bool' seems to do what I want, but how do I convert a symbol string into a 'Name'?

Thanks for any hints!

Greetings, Daniel _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

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Daniel Trstenjak

1:19 p.m.

Hi Dan,

Correct me if I am wrong, but you are not supposed to construct 'Name's yourself. The point is that they are unique and hiding the constructors is a step towards preserving the invariants.

Ok, I almost expected something like this.

Here's how I would do something like 'map nameOccName . modInfoExports' and then search for an OccName (which you can construct using mkOccName).

I already tried it this way, but if you're doing this for a lot of modules, than quite a lot of time is just spend creating the list for the returned symbols, which is in my case than immediately discarded after the search. Greetings, Daniel

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Ranjit Jhala

2:32 p.m.

This is something we've had to do in LiquidHaskell. You might look at the function `stringLookupEnv`: https://github.com/ucsd-progsys/liquidhaskell/blob/master/Language/Haskell/L... the key bits are: *hscParseIdentifier*http://www.haskell.org/ghc/docs/latest/html/libraries/ghc/HscMain.html#v:hsc... :: HscEnv -> String -> IO (Located RdrName)http://www.haskell.org/ghc/docs/latest/html/libraries/ghc/HscMain.html#v:hsc... *tcRnLookupRdrName*http://www.haskell.org/ghc/docs/latest/html/libraries/ghc/TcRnDriver.html#v:... :: HscEnv -> RdrName -> IO (Messages, Maybe [Name])http://www.haskell.org/ghc/docs/latest/html/libraries/ghc/TcRnDriver.html#v:... Note that both of these require that you have an `HscEnv` in hand. Also, the hoogle query: "String -> m Name +ghc" brought up: parseNamehttp://www.haskell.org/ghc/docs/latest/html/libraries/ghc/InteractiveEval.ht... :: GhcMonad m => String -> m [Name]http://www.haskell.org/ghc/docs/latest/html/libraries/ghc/InteractiveEval.ht... which seems like it may be helpful if you don't want to manually pass around HscEnvs... Hope this helps! On Sat, Oct 19, 2013 at 10:19 AM, Daniel Trstenjak < daniel.trstenjak@gmail.com> wrote:

Hi Dan,

...
Correct me if I am wrong, but you are not supposed to construct 'Name's yourself. The point is that they are unique and hiding the constructors is a step towards preserving the invariants.

Ok, I almost expected something like this.

...
Here's how I would do something like 'map nameOccName . modInfoExports' and then search for an OccName (which you can construct using mkOccName).

I already tried it this way, but if you're doing this for a lot of modules, than quite a lot of time is just spend creating the list for the returned symbols, which is in my case than immediately discarded after the search.

Greetings, Daniel

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Daniel Trstenjak

20 Oct 20 Oct

7:41 a.m.

Hi Ranjit, unfortunately both versions don't seem to work.

parseName :: GhcMonad m => String -> m [Name]

This version yields an exception - I can't remember the exact text - but something like symbol not found.

hscParseIdentifier :: HscEnv -> String -> IO (Located RdrName) tcRnLookupRdrName :: HscEnv -> RdrName -> IO (Messages, Maybe [Name])

By this version the returned names by tcRnLookupRdrName are empty and also the returned messages are empty, or 'printBagOfErrors' doesn't output anything for them. Greetings, Daniel

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Dan Frumib
Daniel Trstenjak
Ranjit Jhala