September Morn Update

Task/Fractran/Haskell/fractran-3.hs

@@ -1,3 +1,3 @@
-readProgram :: String -> [Ratio a]
+readProgram :: String -> [Ratio Int]
 readProgram = map (toFrac . splitOn "/") . splitOn ","
   where toFrac [n,d] = read n % read d

Task/Fractran/Haskell/fractran-4.hs

@@ -1 +1,2 @@
 import Data.Maybe (mapMaybe)
+import Data.List (elemIndex)

Task/Fractran/Haskell/fractran-5.hs

@@ -1,6 +1,20 @@
+primes :: [Int]
 primes = mapMaybe log2 $ fractran prog 2
   where
-    prog = [17 % 91, 78 % 85, 19 % 51, 23 % 38, 29 % 33
-           ,77 % 29, 95 % 23, 77 % 19, 1 % 17, 11 % 13
-           ,13 % 11, 15 % 14, 15 % 2, 55 % 1]
-    log2 = fmap (+ 1) . findIndex (== 2) . takeWhile even . iterate (`div` 2)
+    prog =
+      [ 17 % 91
+      , 78 % 85
+      , 19 % 51
+      , 23 % 38
+      , 29 % 33
+      , 77 % 29
+      , 95 % 23
+      , 77 % 19
+      , 1 % 17
+      , 11 % 13
+      , 13 % 11
+      , 15 % 14
+      , 15 % 2
+      , 55 % 1
+      ]
+    log2 = fmap succ . elemIndex 2 . takeWhile even . iterate (`div` 2)