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Today's Topics:
1. Re: Tying the knot (Heinrich Apfelmus)
2. QuickCheck documentation (Christian Maeder)
3. Re: QuickCheck documentation (Stephen Tetley)
----------------------------------------------------------------------
Message: 1
Date: Wed, 05 Jan 2011 14:55:19 +0100
From: Heinrich Apfelmus <[email protected]>
Subject: Re: [Haskell-beginners] Tying the knot
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8; format=flowed
aditya siram wrote:
> My brain turns into strange braid when I see this kind of thing. I
> don't quite understand it and I've never used it in real world code
> but I'll try and explain anyway. Caveat emptor.
>
> [..]
>
> Now look at 'n' and imagine it was a memory location. Mentally
> substitute some hex address (like 0x0000) if it makes it easier.
Another way to look at it is to observe that the result n does not
depend on the input n , even though the notation might suggest otherwise.
To see that, let _|_ denote an expression that is undefined , i.e.
raises an error when you try to evaluate at it. Using the definition
data Tree a = Branch (Tree a) (Tree a) | Leaf a
label n (Branch a b) = (na+nb, Branch a' b')
where
(na,a') = label n a
(nb,b') = label n b
label n (Leaf _) = (1, Leaf n)
we have
label _|_ (Branch (Leaf 'c') (Leaf 'd'))
= (na+nb, Branch a' b')
where (na,a') = label _|_ (Leaf 'c')
(nb,b') = label _|_ (Leaf 'd')
= (1+1, Branch (Leaf _|_) (Leaf _|_))
So, even though the argument n is undefined, the function label
still produces a partially defined result.
Regards,
Heinrich Apfelmus
--
http://apfelmus.nfshost.com
------------------------------
Message: 2
Date: Wed, 05 Jan 2011 18:07:10 +0100
From: Christian Maeder <[email protected]>
Subject: [Haskell-beginners] QuickCheck documentation
To: [email protected]
Cc: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=UTF-8
Hi,
where can I find the best documentation for using QuickCheck?
I use version QuickCheck-2.1.1.1 that is in the current Haskell Platform
2010.2.0.0.
Thanks Christian
(The links to home pages
http://www.cse.chalmers.se/~koen
http://www.math.chalmers.se/~rjmh/QuickCheck/
are pretty dead.)
------------------------------
Message: 3
Date: Wed, 5 Jan 2011 18:16:09 +0000
From: Stephen Tetley <[email protected]>
Subject: Re: [Haskell-beginners] QuickCheck documentation
Cc: [email protected]
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
The first QuickCheck paper works as a tutorial although there are some
changes in QuickCheck2 that are slightly incompatible.
Papers that the author made available but where the home page has
disappeared are often on CiteSeer or KFUPM - King Fahd University of
Petroleum and Minerals. KFUPM seems to be more reliable than CiteSeer
these days:
http://reference.kfupm.edu.sa/
A Lightweight Tool for Random Testing of Haskell Programs
http://reference.kfupm.edu.sa/content/q/u/quickcheck__a_lightweight_tool_for_rando_73653.pdf
A bit more advanced :
http://reference.kfupm.edu.sa/content/t/e/testing_monadic_code_with_quickcheck_69509.pdf
------------------------------
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