Reorganized code to add Debris class

src/Debris.hs

@@ -0,0 +1,21 @@
+{-# LANGUAGE ExistentialQuantification #-}
+
+module Debris ( Debris(..)
+              , SomeDebris(..)
+              ) where
+
+import Tank
+
+class Show a => Debris a where
+    collideTank :: a -> Tank -> Tank
+
+
+data SomeDebris = forall a. Debris a => SomeDebris a
+
+instance Show SomeDebris
+    where
+      show (SomeDebris a) = show a
+
+instance Debris SomeDebris
+    where
+      collideTank (SomeDebris a) = collideTank a