Yes, thanks. This is a known bug in 5.04. What is interesting to me is how many people are using self-recursive newtypes, with no intervening data types. That is, a type that would be infinite if the newtype were a type synonym. At least four people have independently reported the bug, so they are each making use of this infinite-type stuff.
I'm sure there's a programming pearl in there... "Applications of infinite types". If anyone wants to write it, I can probably dig out the four instances. Simon | -----Original Message----- | From: Alain Cremieux [mailto:[EMAIL PROTECTED]] | Sent: 12 September 2002 21:15 | To: [EMAIL PROTECTED] | Subject: Stack overflow | | Hi, | | The following code compiles OK with hugs (dec 2001) but produces a loop | & stack overflow with GHC 5.04 | | data Ctx m a b = forall i. CBCC (a -> CUT m i -> CUT m i) (CUT m i) | (Ctx m i b) | newtype CUT m a = MkCut (forall b. Ctx m a b -> m b) | | promote :: Monad m => m a -> CUT m a | promote m = MkCut (\ctx0 -> case ctx0 of | CBCC c f ctx -> m >>= (\a -> | let MkCut q = c a f | | in q ctx)) | | | when I replace the 'newtype' by 'data', it compiles again with GHC | | - the code is taken (and simplified) from "Deriving Backtracking Monad | Transformers" from Ralph Hinze | - compiled with -fglasgow-exts (of course), Linux and Windows versions | of GHC and GHCI 5.04 | | Alain | | _______________________________________________ | Glasgow-haskell-bugs mailing list | [EMAIL PROTECTED] | http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs _______________________________________________ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
