move askNumber to utils

Utils.hs

@@ -0,0 +1,15 @@
+module Utils (askNumber) where
+
+import Text.Read (readMaybe)
+import System.Exit (exitSuccess)
+
+-- Ask user for an integer > 1, or exit on invalid input
+askNumber :: String -> IO Integer
+askNumber s = do
+    putStrLn s
+    input <- getLine
+    case readMaybe input of
+        Just n | n > 1 -> return n
+        _ -> do
+            putStrLn "Not a valid integer"
+            exitSuccess