User:WillNess
Jump to navigation
Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
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.