Data commit

Task/Hailstone-sequence/Egel/hailstone-sequence.egel

@@ -0,0 +1,42 @@
+import "prelude.eg"
+
+namespace Hailstone (
+
+    using System
+    using List
+
+    def even = [ N -> (N%2) == 0 ]
+
+    def hailstone =
+        [ 1 -> {1}
+        | N -> if even N then cons N (hailstone (N/2))
+               else cons N (hailstone (N * 3 + 1)) ]
+
+    def hailpair =
+        [ N -> (N, length (hailstone N)) ]
+
+    def hailmax =
+        [ (N, NMAX), (M, MMAX) -> if (NMAX < MMAX) then (M, MMAX) else (N, NMAX) ]
+
+    def largest =
+        [ 1 -> (1, 1)
+        | N ->
+            let M0 = hailpair N in
+            let M1 = largest (N - 1) in
+                hailmax M0 M1 ]
+)
+
+using System
+using List
+using Hailstone
+
+def task0 = let H27 = hailstone 27 in length H27
+
+def task1 =
+    let H27 = hailstone 27 in
+    let L   = length H27 in
+        (take 4 H27, drop (L - 4) H27)
+
+def task2 = largest 100000
+
+def main = (task0, task1, task2)