Data commit

Task/Pierpont-primes/Haskell/pierpont-primes.hs

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+import Control.Monad (guard)
+import Data.List (intercalate)
+import Data.List.Split (chunksOf)
+import Math.NumberTheory.Primes (Prime, unPrime, nextPrime)
+import Math.NumberTheory.Primes.Testing (isPrime)
+import Text.Printf (printf)
+
+data PierPointKind = First | Second
+
+merge :: Ord a => [a] -> [a] -> [a]
+merge [] b = b
+merge a@(x:xs) b@(y:ys) | x < y     = x : merge xs b
+                        | otherwise = y : merge a ys
+
+nSmooth :: Integer -> [Integer]
+nSmooth p = 1 : foldr u [] factors
+ where
+  factors = takeWhile (<=p) primes
+  primes = map unPrime [nextPrime 1..]
+  u n s = r
+   where
+    r = merge s (map (n*) (1:r))
+
+pierpoints :: PierPointKind -> [Integer]
+pierpoints k = do
+  n <- nSmooth 3
+  let x = case k of First  -> succ n
+                    Second -> pred n
+  guard (isPrime x) >> [x]
+
+main :: IO ()
+main = do
+  printf "\nFirst 50 Pierpont primes of the first kind:\n"
+  mapM_ (\row -> mapM_ (printf "%12s" . commas) row >> printf "\n") (rows $ pierpoints First)
+  printf "\nFirst 50 Pierpont primes of the second kind:\n"
+  mapM_ (\row -> mapM_ (printf "%12s" . commas) row >> printf "\n") (rows $ pierpoints Second)
+  printf "\n250th Pierpont prime of the first kind: %s\n" (commas $ pierpoints First !! 249)
+  printf "\n250th Pierpont prime of the second kind: %s\n\n" (commas $ pierpoints Second !! 249)
+ where
+  rows = chunksOf 10 . take 50
+  commas = reverse . intercalate "," . chunksOf 3 . reverse . show