GHC Error in linker "undeined reference"

[Johan Grönqvist]

Hello,

I am using ghc on ubuntu 6.06, and it has worked well for my first few 
attempts (one example pasted below), but I now have a file that works 
well in ghci, but not in ghc.

When loading the file (pasted below) into ghci, it works fine.and the 
program runs as expected. Compilation (linking, actually) with ghc gives 
error messages (pasted below), but when I again start ghci adn load the 
program, I can see that it now uses the compiled ".o"-file instead of 
interpreting the program.

I assume that some files that should be installed by default are not 
installed.

I apologize if I am violating any policy about pasting in messages.

Thanks in advance for any help

/ johan

----------------------------------------------------
-- Working example:
sort [] = []
sort (x:xs) = insert x (sort xs)
     where insert x [] = [x]
           insert x (y:ys) | x <= y = (x:y:ys)
                           | otherwise = y : (insert x ys)



main = print $ sort [1,4,53,45,1,435,45,45,1,435,45,145,45345,3,345]
----------------------------------------------------------


------------------------------------------------------
-- Non-linkable example
{-# OPTIONS_GHC -fglasgow-exts #-}

import Control.Monad.State
import Control.Monad.ST
import Data.Array.ST
import Data.List

class Stack s a where
	emptyStack :: (s a)
	isEmpty :: State (s a) Bool
  	pop :: State (s a) a
	push :: a -> State (s a) ()
	nTh :: Int -> State (s a) a
	depth :: State (s a) Int

instance Stack [] a where
	emptyStack =  [] :: [a]
	isEmpty = get >>= \lst -> return (length lst == 0)
	pop = get >>= \(x:xs) -> put xs >> return x
  	push x = get >>= \xs -> put (x:xs) >> return ()
	nTh n = get >>= \lst -> return $ lst !! n
	depth = get >>= (return . length)



class Mem m a where
	emptyMem :: Int -> a -> ST s (m s Int a)
	fetch :: (m s Int a) -> Int -> ST s a
	store :: (m s Int a) -> Int -> a -> ST s ()

instance Mem STArray a where
	emptyMem n val = newArray (0,n) val :: ST s (STArray s Int a)
	fetch m ix = readArray m ix
	store m ix val = writeArray m ix val

stackTest = evalState doStackTest (emptyStack :: [Int]) where
		doStackTest = (push 4 >> 	push 2 >> pop >>= \a -> pop >>= \b -> return 
(a,b))

memTest = runST doMemTest 	where
	doMemTest :: ST s (Int,Int)
	doMemTest = ((emptyMem 2 0 :: ST s (STArray s Int Int))  >>= \mem -> 
store mem 0 2 >>  store mem 1 4 >> fetch mem 0 >>= \a -> fetch mem 1 >>= 
\b -> return (a,b))

main = (print stackTest >> print memTest >> return ())
--------------------------------------------------------------------


Error messages frm ghc:
----------------------------------------------------
ubuntu at ubuntu:~/haskell/Forth$ ghc forth.lhs
forth.o: In function `s2Q0_info': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: In function `s2Q6_info': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: In function `s2Qp_info': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: In function `s2QA_info': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: In function `s2R5_info': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: more undefined references to 
`ControlziMonadziState_zdfMonadStates_closure' follow
forth.o: In function `s2TI_info': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `s2TL_info': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `s2Tm_info': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `s2Tp_info': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `s2TO_info': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `r2Pv_info': undefined reference to 
`ControlziMonadziState_evalState_closure'
forth.o: In function `__stginit_Main_': undefined reference to 
`__stginit_ControlziMonadziState_'
forth.o: In function `Main_zdfStackZMZN_srt': undefined reference to 
`ControlziMonadziState_zdfMonadStates_closure'
forth.o: In function `s2TO_srt': undefined reference to 
`ControlziMonadziState_zdfMonadState_closure'
forth.o: In function `r2Pv_srt': undefined reference to 
`ControlziMonadziState_evalState_closure'
collect2: ld returned 1 exit status
---------------------------------------------------