Hello Shen, I’m not sure if I’m answering exactly what you’re asking, but perhaps this can move you in the right direction:
- To apply an expression to some types, you can use mkTyApps, in the CoreSyn module. The type of that function (Expr b -> [Type] -> Expr b) should be self-explanatory. - To get the instance environments (where all class instances are stored), use tcGetInstEnvs, in the Inst module. - Then, to get the actual dictionary, you can do the lookup with lookupInstEnv, in the InstEnv module. Does this move you in the right direction? Richard On Apr 24, 2014, at 5:37 PM, Shen Chen Xu <shenche...@gmail.com> wrote: > Hello everyone, > > I would like to write a GHC plugin which adds wrapper to functions. Say I have > a function > > addWrapper :: Ord a => (a -> b) -> a -> b > > which is supposed to transform (assuming the argument is in the Ord class) > > foo = \ x -> ... > > into > > foo = addWrapper (\ x -> ...) > > This works fine if I'm only interested in wrapping functions of type Int -> > Int, in which case I make addWrapper to also have type > > addWrapper :: (Int -> Int) -> Int -> Int > > and use mkCoreApp to apply addWrapper to the right hand side. > > However, if I want it to be polymorphic as described above, the transformed > GHC > Core for an Int -> Int function should look like > > foo = addHook @ GHC.Types.Int @ GHC.Types.Int GHC.Classes.$fOrdInt (\ x -> > ...) > > My question is, given the right hand side of foo, how do I construct the > type/type class information inside Core shown above? > > Cheers, > Shen > > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
