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|
-- The translation of this program should assign only one dictionary to
-- the function search (an Ord dictionary). Instead, it assigns two.
-- The output produced currently displays this.
-- 10/12/92: This program is actually erroneous. The pattern-binding for
-- search falls under the monomorphism restriction, and there is no
-- call to search which might fix its type. So there should be a complaint.
-- But the actual error message is horrible:
--
-- "bug001.hs", line 26: Ambiguous overloading:
-- class "Ord_", type "a" (at a use of an overloaded identifier: gt)
-- class "Eq_", type "a" (at a use of an overloaded identifier: eq)
module TcFail where
class Eq_ a where
eq :: a -> a -> Bool
instance Eq_ Int where
eq = eqIntEq
instance (Eq_ a) => Eq_ [a] where
eq = \ xs ys ->
if (null xs)
then (null ys)
else if (null ys)
then False
else (&&) (eq (hd xs) (hd ys)) (eq (tl xs) (tl ys))
class (Eq_ a) => Ord_ a where
gt :: a -> a -> Bool
instance Ord_ Int where
gt = ordIntGt
search
= \ a bs -> if gt (hd bs) a
then False
else if eq a (hd bs) then True else search a (tl bs)
hd :: [a] -> a
hd (a:as) = a
tl :: [a] -> [a]
tl (a:as) = as
ordIntGt :: Int -> Int -> Bool
ordIntGt 2 3 = True
eqIntEq :: Int -> Int -> Bool
eqIntEq 2 3 = True
{-
===============================================
Main.Eq__INST_PreludeBuiltin.Int =
let
AbsBinds [] [] [(eq, eq)]
{- nonrec -}
{-# LINE 2 "test3.hs" -}
eq :: PreludeBuiltin.Int -> PreludeBuiltin.Int -> PreludeCore.Bool
eq = Main.eqIntEq
in ({-dict-} [] [eq])
Main.Eq__INST_PreludeBuiltin.List =
/\ t135 ->
\{-dict-} _dict138 ->
let
{- nonrec -}
_dict136 = {-singleDict-} _dict138
{- nonrec -}
_dict129 = {-singleDict-} _dict136
AbsBinds [] [] [(eq, eq)]
{- nonrec -}
_dict133 =
Main.Eq__INST_PreludeBuiltin.List
[t135] [{-singleDict-} _dict136]
{- nonrec -}
{-# LINE 5 "test3.hs" -}
eq :: [t135] -> [t135] -> PreludeCore.Bool
eq = \ xs ys ->
if (Main.null t135) xs then
(Main.null t135) ys
else
if (Main.null t135) ys then
PreludeCore.False
else
Main.and
((Main.Eq_.eq t135 _dict129)
((Main.hd t135) xs)
((Main.hd t135) ys))
(Main.Eq_.eq [t135] _dict133)
((Main.tl t135) xs)
((Main.tl t135) ys))
in ({-dict-} [] [eq])
Main.Ord__INST_PreludeBuiltin.Int =
let
{- nonrec -}
_dict142 = Main.Eq__INST_PreludeBuiltin.Int [] []
AbsBinds [] [] [(gt, gt)]
{- nonrec -}
{-# LINE 16 "test3.hs" -}
gt :: PreludeBuiltin.Int -> PreludeBuiltin.Int -> PreludeCore.Bool
gt = Main.ordIntGt
in ({-dict-} [_dict142] [gt])
Main.Eq_.eq = /\ a -> \{-classdict-} [] [eq] -> eq
Main.Ord_.gt = /\ a -> \{-classdict-} [_dict56] [gt] -> gt
Main.Ord__TO_Main.Eq_ = /\ a -> \{-classdict-} [_dict58] [gt] -> ???_dict58???
AbsBinds [t60] [] [(hd, Main.hd)]
{- nonrec -}
hd :: [t60] -> t60
hd (a PreludeBuiltin.: as)
= a
AbsBinds [t68] [] [(tl, Main.tl)]
{- nonrec -}
tl :: [t68] -> [t68]
tl (a PreludeBuiltin.: as)
= as
AbsBinds [t91] [_dict85, _dict88] [(search, Main.search)]
{- rec -}
{-# LINE 19 "test3.hs" -}
search :: t91 -> [t91] -> PreludeCore.Bool
search
= \ a bs ->
if (Main.Ord_.gt t91 _dict85) ((Main.hd t91) bs) a then
PreludeCore.False
else
if (Main.Eq_.eq t91 _dict88) a ((Main.hd t91) bs) then
PreludeCore.True
else
search a ((Main.tl t91) bs)
AbsBinds [] [] [(and, Main.and)]
{- nonrec -}
and :: PreludeCore.Bool -> PreludeCore.Bool -> PreludeCore.Bool
and PreludeCore.True PreludeCore.True
= PreludeCore.True
AbsBinds [] [] [(ordIntGt, Main.ordIntGt)]
{- nonrec -}
_dict97 = PreludeCore.Num_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict98 = PreludeCore.Eq_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict100 = PreludeCore.Num_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict101 = PreludeCore.Eq_INST_PreludeBuiltin.Int [] []
{- nonrec -}
ordIntGt :: PreludeBuiltin.Int -> PreludeBuiltin.Int -> PreludeCore.Bool
ordIntGt
2 3 = PreludeCore.True
AbsBinds [] [] [(eqIntEq, Main.eqIntEq)]
{- nonrec -}
_dict105 = PreludeCore.Num_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict106 = PreludeCore.Eq_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict108 = PreludeCore.Num_INST_PreludeBuiltin.Int [] []
{- nonrec -}
_dict109 = PreludeCore.Eq_INST_PreludeBuiltin.Int [] []
{- nonrec -}
eqIntEq :: PreludeBuiltin.Int -> PreludeBuiltin.Int -> PreludeCore.Bool
eqIntEq
2 3 = PreludeCore.True
AbsBinds [t112] [] [(null, Main.null)]
{- nonrec -}
null :: [t112] -> PreludeCore.Bool
null [] = PreludeCore.True
-}
|
