[Haskell-cafe] This is an interesting place to showcase Haskell.

[Dan Weston]

It does not bode well that the first example I looked at (which I chose 
because it maximally would highlight the benefits of Haskell over other 
languages):

http://en.literateprograms.org/Sieve_of_Eratosthenes_%28Haskell%29

has the following "Haskell" program.

   primes :: [Int] -> [Int]
   primes :: [] -> []
   primes (n:ns) = n : primes (filter (\v -> v `mod` n /= 0) ns)

Not only are there two conflicting type declarations (making this 
uncompilable), but after the "obvious" syntactic fix:

primes :: [Int] -> [Int]
primes []     = []
primes (n:ns) = n : primes (filter (\v -> v `mod` n /= 0) ns)

primes (n:ns) gives the wrong answer unless n == 2.

*P> primes [2..47]
[2,3,5,7,11,13,17,19,23,29,31,37,41,43,47]

*P> primes [5..47]
[5,6,7,8,9,11,13,17,19,23,29,31,37,41,43,47]

*P> length . primes $ [100..200]
100

As there are so far relatively few Haskell programs listed (~100), 
perhaps an interested party might go through and do a sanity check on them.

Dan

Michael T. Richter wrote:
> http://en.literateprograms.org/LiteratePrograms:Welcome
> 
> There's some Haskell there already, but I think a lot more could be 
> shown there.  Even code dumps of things would be nice.  They can always 
> be explained later.
> 
> -- 
> *Michael T. Richter* <ttmrichter at gmail.com 
> <mailto:ttmrichter at gmail.com>> (*GoogleTalk:* ttmrichter at gmail.com)
> /Never, ever, ever let systems-level engineers do human interaction 
> design unless they have displayed a proven secondary talent in that 
> area. Their opinion of what represents good human-computer interaction 
> tends to be a bit off-track. (Bruce Tognazzini)/
> 
> 
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