Add files, minimal working rewind gun that must be equipped to charge

src/Dodge/Item/Weapon/Utility.hs

@@ -26,8 +26,11 @@ rewindGun = defaultGun
     , _itUse = Left $ \cr invid -> useRewindGun (_crInv cr IM.! invid) cr
     }
 rewindEffect :: ItEffect -> Creature -> Int -> World -> World
-rewindEffect _ cr invid w = w & rewindWorlds %~ (take 250 . (w' : ))
-    & creatures . ix (_crID cr) . crInv . ix invid . wpLoadedAmmo .~ length (_rewindWorlds w)
+rewindEffect _ cr invid w 
+    | Just invid == _crLeftInvSel cr = w & rewindWorlds %~ (take 250 . (w' : ))
+        & creatures . ix (_crID cr) . crInv . ix invid . wpLoadedAmmo .~ length (_rewindWorlds w)
+    | otherwise = w & rewindWorlds .~ []
+        & creatures . ix (_crID cr) . crInv . ix invid . wpLoadedAmmo .~ 0
   where
     w' = w & rewindWorlds .~ []
         & rewinding .~ True

src/ListHelp.hs

@@ -0,0 +1,9 @@
+module ListHelp 
+    (module Data.List
+    ,initOrNull
+    )where
+import Data.List
+
+initOrNull :: [a] -> [a]
+initOrNull [] = []
+initOrNull xs = init xs

src/MaybeHelp.hs

@@ -0,0 +1,15 @@
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE StrictData #-}
+module MaybeHelp where
+import Control.Lens
+
+-- | Strict maybe
+data Maybe' a 
+    = Just' {_Just' :: a }
+    | Nothing'
+
+fromJust' :: Maybe' a -> a
+fromJust' mx = case mx of
+    Just' x -> x
+    Nothing' -> error "no fromJust'"
+makeLenses ''Maybe'