Yellowstone sequence: Difference between revisions

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 yellowstone :: [Integer]
-yellowstone = 1 : 2 : 3 : unfoldr (Just . f) (2,3,[4..]) where
+yellowstone = 1 : 2 : 3 : unfoldr (Just . f) (2, 3, [4 ..])
+  where
-  f :: (Integer, Integer, [Integer]) -> (Integer, (Integer, Integer, [Integer]))
+    f ::
-  f (p2, p1, rest) = (next, (p1, next, rest_)) where
-    (next, rest_) = select rest
+      (Integer, Integer, [Integer]) ->
-    select :: [Integer] -> (Integer, [Integer])
+      (Integer, (Integer, Integer, [Integer]))
+    f (p2, p1, rest) = (next, (p1, next, rest_))
-    select (x:xs)
+      where
-      | gcd x p1 == 1 && gcd x p2 /= 1 = (x, xs)
-      | otherwise = (y, x:ys)
+        (next, rest_) = select rest
+        select :: [Integer] -> (Integer, [Integer])
-      where (y, ys) = select xs
+        select (x : xs)
+          | gcd x p1 == 1 && gcd x p2 /= 1 = (x, xs)
+          | otherwise = (y, x : ys)
+          where
+            (y, ys) = select xs
 main :: IO ()