[Haskell-cafe] Template Haskell -- Bug?

20 Oct 2005

      Hi,

Could somebody try to compile these two files *TWICE*? GHC dumps core at 
me. I don't know if it is something about me, or something more general 
:) I'd like to know a bit more, before I bother anybody from devel team.

Log:

$ ghc --make THTest1.hs
Chasing modules from: THTest1.hs
Compiling THTest1TH        ( ./THTest1TH.hs, ./THTest1TH.o )
Compiling THTest1          ( THTest1.hs, THTest1.o )

THTest1.hs:10:4: `incrSelf' is not a (visible) method of class `IncrSelf'

$ ghc --make THTest1.hs
Chasing modules from: THTest1.hs
Skipping  THTest1TH        ( ./THTest1TH.hs, ./THTest1TH.o )
Compiling THTest1          ( THTest1.hs, THTest1.o )
Loading package base-1.0 ... linking ... done.
Loading package haskell98-1.0 ... linking ... done.
Loading package template-haskell-1.0 ... linking ... done.
(here core dump, aka 0xc00000001)

First of all, I do not understand the error in first compilation. 
Second, core dump is not nice :)

My config:

Windows XP Home,

$ ghc -v
Glasgow Haskell Compiler, Version 6.4, for Haskell 98, compiled by GHC 
version 6.2.2
Using package config file: c:\ghc\ghc-6.4\package.conf
Using package config file: C:\Documents and Settings\gracjan\Application 
Data\ghc/i386-mingw32-6.4/package.conf

Default windows package as taken from www.haskell.org.

-- 
Gracjan

{-# OPTIONS -fglasgow-exts -fth -fallow-undecidable-instances #-}

module THTest1TH
(
  instanceIncrSelfTuple,
  IncrSelf(..)
)
where
import Control.Monad
import Data.Maybe
import Language.Haskell.TH

class IncrSelf a where
    incrSelf :: a -> a

instance Num a => IncrSelf a where
    incrSelf x = x + 1

sel' :: Int -> Int -> ExpQ
sel' i n = lamE [pat] rhs
    where pat = tupP (map varP as)
          rhs = varE (as !! (i - 1))
          as = map mkName [ ("a__" ++ show j) | j <- [1..n] ]

instanceIncrSelfTuple :: Int -> Q [Dec]
instanceIncrSelfTuple n = do
     decs <- qOfDecs
     let listOfDecQ = map return decs
         conIncrSelf = conT ''IncrSelf
         name_a = mkName "a"
         name_b = mkName "b"
         name_c = mkName "c"
         var_a = varT name_a
         var_b = varT name_b
         var_c = varT name_c
     dec <- instanceD (sequence [appT conIncrSelf var_a,appT conIncrSelf var_b])
                                (appT conIncrSelf
                                      (appT
                                             (appT (tupleT 2)
                                                   var_a
                                             )
                                             var_b
                                       )
                                 )
                listOfDecQ
     return [dec]
     where qOfDecs = [d|
                incrSelf value =
                    let
                        value1 = maybe Nothing (Just . fst) value
                        value2 = maybe Nothing (Just . snd) value
                    in error "adfasf" -- (incrSelf value1, incrSelf value2)
                |]

{-# OPTIONS -fglasgow-exts -fth -fallow-undecidable-instances  #-}

module THTest1
where
import THTest1TH

instance IncrSelf String where
    incrSelf x = x ++ "x"

$(instanceIncrSelfTuple 2)

[Haskell-cafe] Template Haskell -- Bug?

Gracjan Polak