Since there occurred problems with e-mail delivery, i am sorry,
i repeat the two bug reports for ghc-4-i386-linux.
------------------
Sergey Mechveliani
[EMAIL PROTECTED]
*****************************************************************
1. The reduced `panic' example: ghc -c Bug.hs
ft does not look natural. But after `panic' is fixed, i hope the
original program will work.
By the way, has
class PolLike p where cPMul :: Eq a => a -> p a -> p a
----
sense? I thought, yes.
-------------------------------------------------------------------
class PolLike p where cPMul :: Eq a => a -> p a -> p a
class Eq a => AddSemigroup a where add :: a -> a -> a
type UMon a = (a, Integer )
type Monomial a = (a, [Integer])
data UPol a = UPol [UMon a] a String [a]
instance Eq a => Eq (UPol a)
instance PolLike UPol where cPMul _ _ = error ""
instance Eq a => AddSemigroup (UPol a)
ft :: AddSemigroup k => UPol k -> [UPol k]
ft f@(UPol _ c v d) =
let
berl h = let b = [cPMul c h]
fr = map (const []) [cPMul c h]
in
case head fr
of
_:_ -> let es = map (add (UPol [] c v d)) [h]
in berl h
in
berl f
*********************************************************************
2. Modularity bug:
-----------------------------------------------------
module T1 where
type Z = Integer
toZ = toInteger :: Integral a => a -> Z
-- the idea is to switch Z, toZ between Integer, Int
-----------------------------------------------------
module Main where
import List (genericTake)
import T1 (Z, toZ )
f :: Z -> Z -> [Z]
f n i = case toZ i of j -> genericTake (n+j) (repeat n)
main = let ns = f 2 3 in putStr (shows ns "\n")
-----------------------------------------------------------------
After ghc -c T1.hs, ghc -c Main.hs
the compiler derives a contradiction for i :: Int, Z.
After moving the definition of toZ to Main.hs the compiler solves
the types differently.
