Re: [Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
On Wed, Apr 04, 2007 at 10:59:45PM +0100, Joel Reymont wrote: > One last bit then... > > My identifiers should start with letter <|> char '_' and the tail > should be alphaNum <|> char '_'. > > I guess I can use choose and oneof to produce the right set of > characters but how do I combine the two into a single identifier of > a given length (up to 20 chars, say)? > > Thanks, Joel > > On Apr 4, 2007, at 5:27 PM, Fawzi Mohamed wrote: > > >Great, just one thing that could be important : when you have > >recursive structures (like your Statement through Compound) be sure > >to use > >sized (\mySize -> ...) > >as generator for arbitrary so that you can avoid infinite looping. quickcheck is a monad so you can just do: do first <- elements $ '_' : ['a' .. 'z'] len <- elements $ [5..19] rest <- replicateM len $ elements $ '_' : ['a' .. 'z'] ++ ['0' .. '9'] return (first : rest) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
One last bit then... My identifiers should start with letter <|> char '_' and the tail should be alphaNum <|> char '_'. I guess I can use choose and oneof to produce the right set of characters but how do I combine the two into a single identifier of a given length (up to 20 chars, say)? Thanks, Joel On Apr 4, 2007, at 5:27 PM, Fawzi Mohamed wrote: Great, just one thing that could be important : when you have recursive structures (like your Statement through Compound) be sure to use sized (\mySize -> ...) as generator for arbitrary so that you can avoid infinite looping. -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
Joel Reymont wrote: I got this simple example working so I think I have my question answered. Great, just one thing that could be important : when you have recursive structures (like your Statement through Compound) be sure to use sized (\mySize -> ...) as generator for arbitrary so that you can avoid infinite looping. Look at http://www.cs.chalmers.se/~rjmh/QuickCheck/manual_body.html#15 for an example. Fawzi Now I just have to learn to write generators of my own to produce valid and invalid input for my parser. module Foo where import Control.Monad import System.Random import Test.QuickCheck data Foo = Foo Int | Bar | Baz deriving Show instance Arbitrary Foo where coarbitrary = undefined arbitrary = oneof [ return Bar , return Baz , liftM Foo arbitrary ] gen' rnd = generate 1 rnd $ vector 5 :: [Foo] gen = do { rnd <- newStdGen ; return $ gen' rnd } -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Re: QuickCheck: Arbitrary for a complex type
I got this simple example working so I think I have my question answered. Now I just have to learn to write generators of my own to produce valid and invalid input for my parser. module Foo where import Control.Monad import System.Random import Test.QuickCheck data Foo = Foo Int | Bar | Baz deriving Show instance Arbitrary Foo where coarbitrary = undefined arbitrary = oneof [ return Bar , return Baz , liftM Foo arbitrary ] gen' rnd = generate 1 rnd $ vector 5 :: [Foo] gen = do { rnd <- newStdGen ; return $ gen' rnd } -- http://wagerlabs.com/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe