Alejandro, If I understand correctly, you're using the InteractiveEval module from the GHC API. That module exposes a very specific interface, and sometimes you'll need to do things beyond that - my approach has then been to look at the implementation of these things, copy/paste code, and follow the types. This will take you through other modules like HscTypes and so on, but you might be able to figure out how to do what you want. The GHC source code isn't great, but is fairly understandable if you stare at it for long enough. I also very highly encourage you to document what you did on the wiki page for GHC API. The GHC API is in **dire** need of more explained example code using it. -- Andrew On Tue, Jun 3, 2014 at 3:01 PM, Nils Schweinsberg wrote:

I'm not sure what exactly you're trying to do, but with Template Haskell it's easy:

test :: Name -> Q [Dec]

...

test name = do info <- reify name ...

Then call it from another module with the type name as argument (double single quotes):

data Test = A | B

...

test ''Test

The `Info` type returned by `reify` is described in:

http://hackage.haskell.org/package/template-haskell-2.9. 0.0/docs/Language-Haskell-TH-Syntax.html#t:Info

- Nils

Am 03.06.2014 21:13, schrieb Alejandro Serrano Mena:

...

Dear Haskell-Café, As part of my Google Summer of Code, I need to get the list of data constructors of a certain data type on a specific scenario. In my case, I'm getting a value of type Type (by calling exprType). I was expecting to be able to call getInfo directly on that value of type Type, but it doesn't have a name nor the constructors of Type are public. Thus, I'm not able to get that information :(

Thanks in advance, Alejandro

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Hi Alejandro, From your use case, it looks like you need splitTyConApp (from GHC's Type module). Then, tyConDataCons will do the trick. Perhaps splitTyConApp should be in the GHC module itself. If you think so, submit a bug report and patch, please! I don't think Template Haskell will work for you here -- mixing calls from the GHC module and TH is a recipe for disaster. I hope this helps, Richard On Jun 4, 2014, at 8:30 AM, Alejandro Serrano Mena wrote:

My aim is to extend the capabilities of ghc-mod to do case split. For that matter, I'm using the GHC module of the ghc package (the same ghc-mod uses). Via the exprType function I get a Type value. Then, I would like to be able to call getInfo (everything from the GHC module) to get the information of that type.

I'm not sure if using Template Haskell is something I can use, but I will definitely try :)

2014-06-04 0:01 GMT+02:00 Nils Schweinsberg : I'm not sure what exactly you're trying to do, but with Template Haskell it's easy:

test :: Name -> Q [Dec] test name = do info <- reify name ...

Then call it from another module with the type name as argument (double single quotes):

data Test = A | B

test ''Test

The `Info` type returned by `reify` is described in:

http://hackage.haskell.org/package/template-haskell-2.9.0.0/docs/Language-Ha...

- Nils

Am 03.06.2014 21:13, schrieb Alejandro Serrano Mena: Dear Haskell-Café, As part of my Google Summer of Code, I need to get the list of data constructors of a certain data type on a specific scenario. In my case, I'm getting a value of type Type (by calling exprType). I was expecting to be able to call getInfo directly on that value of type Type, but it doesn't have a name nor the constructors of Type are public. Thus, I'm not able to get that information :(

Thanks in advance, Alejandro

_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

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