# User:WillNess

### From HaskellWiki

(Difference between revisions)

## Revision as of 09:43, 29 August 2011

I'm interested in Haskell.

I like *this*:

-- inifinte folding idea due to Richard Bird -- double staged production idea due to Melissa O'Neill -- tree folding idea Dave Bayer / simplified formulation Will Ness primes = 2 : g (fix g) where g ps = 3 : gaps 5 (foldi (\(q:qs) -> (q:) . union qs) [[p*p, p*p+2*p..] | p <- ps]) gaps k s@(c:t) | k < c = k : gaps (k+2) s -- | k<=c = minus [k,k+2..] s | True = gaps (k+2) t -- fused to avoid a space leak fix g = xs where xs = g xs -- global defn to avoid space leak

`foldi`

is on Tree-like folds page. `union`

and more at Prime numbers.

Also, the math formula for Sieve of Eratosthenes,

where

- . . . or, :) :) .

Trial division sieve: