Hi!
The following program dumps core on execution (compiled with ghc-4.04):
\begin{code}
{-# OPTIONS -fglasgow-exts #-}
import IO
import IOExts
{-# notInline test #-}
test :: IORef [a]
test = unsafePerformIO $ newIORef []
main = do
writeIORef test [42]
bang <- readIORef test
print (bang :: [Char])
\end{code}
The problem cause is clear, but is there a way to make the RTS (or type
system) smarter, i.e. not just dumping core (besides from not using IORefs
*this* way ;-))?
The problem is, that these errors may be hard to track down, if the program
dumps core occasionally. For example, the following works without core-dump:
\begin{code}
main = do
writeIORef test [42]
writeIORef test "NO BANG"
bang <- readIORef test
print (bang :: [Char])
\end{code}
Cheers,
Michael
--
If builders built buildings the way programmers wrote programs, then the
first woodpecker that came along would destroy civilization.
-- Gerald Weinberg
