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 | n>2 = 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 | n>1 = 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
_______________________________________________
Haskell-Cafe mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/haskell-cafe
