Cuban primes: Difference between revisions
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→{{header|Haskell}}: Pruned an import, added a list comprehension variant.
m (→{{header|Haskell}}: simplify) |
m (→{{header|Haskell}}: Pruned an import, added a list comprehension variant.) |
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Line 1,007:
Uses Data.Numbers.Primes library: http://hackage.haskell.org/package/primes-0.2.1.0/docs/Data-Numbers-Primes.html<br>
Uses Data.List.Split library: https://hackage.haskell.org/package/split-0.2.3.4/docs/Data-List-Split.html
<lang haskell>import
import Data.List (intercalate)
import Data.List.Split (chunksOf)
Line 1,014 ⟶ 1,013:
cubans :: [Int]
cubans = filter isPrime . map (\x -> (succ x ^ 3) - (x ^ 3)) $ [1 ..]
main :: IO ()
main = do
mapM_ (\row -> mapM_ (printf "%10s" . thousands) row >> printf "\n") $ rows cubans
printf "\nThe 100,000th cuban prime is: %10s\n" $ thousands $ cubans !! 99999
where
rows = chunksOf 10 . take 200
thousands = reverse . intercalate "," . chunksOf 3 . reverse . show</lang>
Where filter over map could also be expressed in terms of concatMap, or a list comprehension:
<lang haskell>cubans :: [Int]
cubans =
[ x
| n <- [1 ..]
, let x = (succ n ^ 3) - (n ^ 3)
, isPrime x ]</lang>
{{out}}
<pre>
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