[Haskell-cafe] New simplified primes; no VIP necessary.

Will Ness will_n48 at yahoo.com
Thu Dec 23 09:08:00 CET 2010


For those who remember the discussion about this about a year ago, it turns out 
there was a simpler version after all lurking somewhere in there (or is it 

I've just posted it to the haskellwiki's Prime Numbers page:

primes = 2: primes' 
    primes' = 3: 5: [7,9..] `minus` tfold
                      [ [p*p,p*p+2*p..] | p <- primes' ]   
    tfold ((x:xs):t)    = x : xs `union` tfold (pairs t)
    pairs ((x:xs):ys:t) = (x: union xs ys) : pairs t

The full code with double-feed, wheel and better folding structure is also 
there. Speed and complexity weren't changed by this. But it is rather 
_short_. :)


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