[Template-haskell] Problem with Labelled Fields

26 Jun 2003

      Hi!

Perhaps there's anybody out there who can help me with the following 
problem with labelled fields (using ghc 6.0).

The easy example modules are:

{- spliceC.hs -}
module spliceC where

import Language.Haskell.THSyntax

data C a = C
   {c_succ :: a -> a
   ,c_pred :: a -> a
   }

instance Lift (C a) where
   lift c =
     recCon "C"
       [fieldExp "c_succ" [| c_succ c |]
       ,fieldExp "c_pred" [| c_pred c |]
       ]

c_succS :: C a -> ExpQ
c_succS c = [| \ a -> c_succ c a |]

sampleC :: C Int
sampleC = C
   {c_succ = \ n -> n + 1
   ,c_pred = \ n -> n - 1
   }

{- main.hs -}
module Main where

import spliceC

sampleC_succ = $(c_succS sampleC)

I suppose that this should bring a function sampleC_succ into scope, 
instantiated for sampleC. But in fact I get
*** Exception: stack overflow

Who's wrong?

Thanks,
Eric

[Template-haskell] Problem with Labelled Fields

Eric Offermann