Re: [Haskell-cafe] ghc overlapping instances - solved
Hello,
Isaac, this works for me.
Thx a lot,
Steffen
2007/12/5, Isaac Dupree [EMAIL PROTECTED]:
Steffen Mazanek wrote:
Hi,
Stefan and Isaac, thx for providing quick advice.
@Stefan: Unfortunately I have to use a list.
@Isaac: I do not get it. Could you please provide a short example of
your
approach?
The question still remains. Which arguments do I have ghc to start with
to
get the same behavior than hugs with -98 +o (here it works).
I provide my example for testing purposes:
module Test where
import Test.QuickCheck
import Monad(liftM,liftM2)
type Program = [Stmt]
data Stmt = Text | IfElse Program Program | While Program deriving (Eq,
Show)
instance Arbitrary [Stmt] where
arbitrary = sized genProg
instance Arbitrary Stmt where
arbitrary = sized genStmt
genStmt::Int-Gen Stmt
genStmt 0 = return Text
genStmt 1 = return Text
genStmt 2 = oneof [return Text, return (While [Text])]
genStmt n | n2 = oneof ([return Text,
liftM While (genProg (n-1))]++
[liftM2 IfElse (genProg k) (genProg
(n-k-1))|k-[1..n-2]])
genProg::Int-Gen Program
genProg 0 = return []
genProg 1 = return [Text]
genProg n | n1 = oneof ((liftM (\x-[x]) (genStmt n)):[liftM2 (:)
(genStmt
k) (genProg (n-k))|k-[1..n-1]])
prop_ConstructParse progr = True
where types = progr::Program
main = mapM_ (\(s,a) - putStrLn s a) [(flowchart construct and
parse,
test prop_ConstructParse)]
is prop_ConstructParse the only thing that breaks when you remove the
instance Arbitrary [Stmt] where arbitrary = sized genProg, or have I
missed something? If that's all, try this (untested) :
prop_ConstructParse = forAll (sized genProg) (\progr - True)
and similarly for other properties.
Or, you _can_ use a newtype for quickcheck-only, something like this:
newtype P = P { unP :: Program }
instance Show P where show = show . unP
instance Arbitrary P where arbitrary = sized genProg . unP
prop_ConstructParse (P progr) = True
Isaac
--
Dipl.-Inform. Steffen Mazanek
Institut für Softwaretechnologie
Fakultät Informatik
Universität der Bundeswehr München
85577 Neubiberg
Tel: +49 (0)89 6004-2505
Fax: +49 (0)89 6004-4447
E-Mail: [EMAIL PROTECTED]
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Re: [Haskell-cafe] ghc overlapping instances
Hi, Stefan and Isaac, thx for providing quick advice. @Stefan: Unfortunately I have to use a list. @Isaac: I do not get it. Could you please provide a short example of your approach? The question still remains. Which arguments do I have ghc to start with to get the same behavior than hugs with -98 +o (here it works). I provide my example for testing purposes: module Test where import Test.QuickCheck import Monad(liftM,liftM2) type Program = [Stmt] data Stmt = Text | IfElse Program Program | While Program deriving (Eq, Show) instance Arbitrary [Stmt] where arbitrary = sized genProg instance Arbitrary Stmt where arbitrary = sized genStmt genStmt::Int-Gen Stmt genStmt 0 = return Text genStmt 1 = return Text genStmt 2 = oneof [return Text, return (While [Text])] genStmt n | n2 = oneof ([return Text, liftM While (genProg (n-1))]++ [liftM2 IfElse (genProg k) (genProg (n-k-1))|k-[1..n-2]]) genProg::Int-Gen Program genProg 0 = return [] genProg 1 = return [Text] genProg n | n1 = oneof ((liftM (\x-[x]) (genStmt n)):[liftM2 (:) (genStmt k) (genProg (n-k))|k-[1..n-1]]) prop_ConstructParse progr = True where types = progr::Program main = mapM_ (\(s,a) - putStrLn s a) [(flowchart construct and parse, test prop_ConstructParse)] 2007/12/4, Stefan O'Rear [EMAIL PROTECTED]: On Tue, Dec 04, 2007 at 03:36:20PM +0100, Steffen Mazanek wrote: Hello, I want to quickcheck a property on a datatype representing programs (=[Stmt]) and need to define a specific instance instance Arbitrary [Stmt] (mainly to restrict the size of the list). In quickcheck an instance Arbitrary of lists is already defined. Which parameters do I have to give ghc such that it accepts such an instance? In hugs -98 +o is enough. I have tried -XOverlappingInstances, -XFlexibleInstances and also -XIncoherentInstances, however I still got an overlapping instances error for this declaration. You shouldn't use lists if you need to have special instance behavior - lists are for perfectly ordinary sequences of things. If a program is just a bunch of unrelated statements, then use [], otherwise use a custom (new)type. Stefan -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFHVcxTFBz7OZ2P+dIRAmtMAJ9xcL0xhG9u+QaIFXwhEEq177ePEgCfUfOf dlDMHAN8ldq2qZ7ctOFkNb4= =hxkS -END PGP SIGNATURE- -- Dipl.-Inform. Steffen Mazanek Institut für Softwaretechnologie Fakultät Informatik Universität der Bundeswehr München 85577 Neubiberg Tel: +49 (0)89 6004-2505 Fax: +49 (0)89 6004-4447 E-Mail: [EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc overlapping instances
Steffen Mazanek wrote:
Hi,
Stefan and Isaac, thx for providing quick advice.
@Stefan: Unfortunately I have to use a list.
@Isaac: I do not get it. Could you please provide a short example of your
approach?
The question still remains. Which arguments do I have ghc to start with to
get the same behavior than hugs with -98 +o (here it works).
I provide my example for testing purposes:
module Test where
import Test.QuickCheck
import Monad(liftM,liftM2)
type Program = [Stmt]
data Stmt = Text | IfElse Program Program | While Program deriving (Eq,
Show)
instance Arbitrary [Stmt] where
arbitrary = sized genProg
instance Arbitrary Stmt where
arbitrary = sized genStmt
genStmt::Int-Gen Stmt
genStmt 0 = return Text
genStmt 1 = return Text
genStmt 2 = oneof [return Text, return (While [Text])]
genStmt n | n2 = oneof ([return Text,
liftM While (genProg (n-1))]++
[liftM2 IfElse (genProg k) (genProg
(n-k-1))|k-[1..n-2]])
genProg::Int-Gen Program
genProg 0 = return []
genProg 1 = return [Text]
genProg n | n1 = oneof ((liftM (\x-[x]) (genStmt n)):[liftM2 (:) (genStmt
k) (genProg (n-k))|k-[1..n-1]])
prop_ConstructParse progr = True
where types = progr::Program
main = mapM_ (\(s,a) - putStrLn s a) [(flowchart construct and parse,
test prop_ConstructParse)]
is prop_ConstructParse the only thing that breaks when you remove the
instance Arbitrary [Stmt] where arbitrary = sized genProg, or have I
missed something? If that's all, try this (untested) :
prop_ConstructParse = forAll (sized genProg) (\progr - True)
and similarly for other properties.
Or, you _can_ use a newtype for quickcheck-only, something like this:
newtype P = P { unP :: Program }
instance Show P where show = show . unP
instance Arbitrary P where arbitrary = sized genProg . unP
prop_ConstructParse (P progr) = True
Isaac
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[Haskell-cafe] ghc overlapping instances
Hello, I want to quickcheck a property on a datatype representing programs (=[Stmt]) and need to define a specific instance instance Arbitrary [Stmt] (mainly to restrict the size of the list). In quickcheck an instance Arbitrary of lists is already defined. Which parameters do I have to give ghc such that it accepts such an instance? In hugs -98 +o is enough. I have tried -XOverlappingInstances, -XFlexibleInstances and also -XIncoherentInstances, however I still got an overlapping instances error for this declaration. Regards, Steffen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc overlapping instances
Steffen Mazanek wrote: Hello, I want to quickcheck a property on a datatype representing programs (=[Stmt]) and need to define a specific instance instance Arbitrary [Stmt] (mainly to restrict the size of the list). you don't always need to use instances. for example, I have (where Predicate is a type I defined which I gave a separate normal Arbitrary instance) arbpredicate :: Gen Predicate arbpredicate = do ... prop_assocUnify :: Property prop_assocUnify = forAll arbpredicate $ \a - forAll arbpredicate $ \b - forAll arbpredicate $ \c - ...boolean result Isaac ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] ghc overlapping instances
On Tue, Dec 04, 2007 at 03:36:20PM +0100, Steffen Mazanek wrote: Hello, I want to quickcheck a property on a datatype representing programs (=[Stmt]) and need to define a specific instance instance Arbitrary [Stmt] (mainly to restrict the size of the list). In quickcheck an instance Arbitrary of lists is already defined. Which parameters do I have to give ghc such that it accepts such an instance? In hugs -98 +o is enough. I have tried -XOverlappingInstances, -XFlexibleInstances and also -XIncoherentInstances, however I still got an overlapping instances error for this declaration. You shouldn't use lists if you need to have special instance behavior - lists are for perfectly ordinary sequences of things. If a program is just a bunch of unrelated statements, then use [], otherwise use a custom (new)type. Stefan signature.asc Description: Digital signature ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
