Cleanup some compiler warnings

ghcidOutput

@@ -1,97 +1,3 @@
-/home/justin/Haskell/loop/src/Dodge/Placement/PlaceSpot.hs:159:5-30: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding: Patterns of type ‘[Point2]’ not matched: []
-    |
-159 |     (p : ps) = orderPolygon qs
-    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/Dodge/Update.hs:319:30-33: warning: [-Wunused-matches]
-    Defined but not used: ‘ssel’
-    |
-319 |         Just (MouseInvChosen ssel esel) -> w
-    |                              ^^^^
-/home/justin/Haskell/loop/src/Dodge/Update.hs:319:35-38: warning: [-Wunused-matches]
-    Defined but not used: ‘esel’
-    |
-319 |         Just (MouseInvChosen ssel esel) -> w
-    |                                   ^^^^
-/home/justin/Haskell/loop/src/Dodge/Update.hs:341:38: warning: [-Wunused-matches]
-    Defined but not used: ‘k’
-    |
-341 | shiftInvItemsUp (_,i) (_,j) (Just (_,k)) w = w
-    |                                      ^
-/home/justin/Haskell/loop/src/Dodge/Update.hs:351:40: warning: [-Wunused-matches]
-    Defined but not used: ‘k’
-    |
-351 | shiftInvItemsDown (_,i) (_,j) (Just (_,k)) w = w
-    |                                        ^
-/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:54:22: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
-    The prefix use of a ‘$’ would denote an untyped splice
-      were the TemplateHaskell extension enabled.
-    Suggested fix: Add whitespace after the ‘$’.
-   |
-54 |         shuffleLinks $(roomRectAutoLinks w h){_rmPmnts = []}
-   |                      ^
-/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:120:44: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
-    The prefix use of a ‘$’ would denote an untyped splice
-      were the TemplateHaskell extension enabled.
-    Suggested fix: Add whitespace after the ‘$’.
-    |
-120 |     let n = length $ filter bottomEdgeTest $_rmLinks centralRoom
-    |                                            ^
-/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:122:29: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
-    The prefix use of a ‘$’ would denote an untyped splice
-      were the TemplateHaskell extension enabled.
-    Suggested fix: Add whitespace after the ‘$’.
-    |
-122 |         tToBTree "rezBoxes" $treeFromTrunk [rezBox thecol, door] $
-    |                             ^
-/home/justin/Haskell/loop/src/Dodge/HeldUse.hs:177:5-59: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding:
-        Patterns of type ‘([Float], StdGen)’ not matched:
-            ([], _)
-            ([_], _)
-            ([_, _], _)
-            ([_, _, _], _)
-    |
-177 |     (a : b : c : d : _, g) = runState thestate $ _randGen w -- randomRs (2, 20) (_randGen w)
-    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/RandomHelp.hs:36:9-35: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding:
-        Patterns of type ‘([a], [a])’ not matched: (_, [])
-   |
-36 |     let (zs, w : ws) = splitAt i ys
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/RandomHelp.hs:51:17-46: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding:
-        Patterns of type ‘([b], [b])’ not matched: (_, [])
-   |
-51 |             let (as, b : bs) = splitAt rand ys
-   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/Multiset.hs:50:9: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding: Patterns of type ‘[a]’ not matched: []
-   |
-50 |         (q:qs) = take (n-k+1) ys
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/Dodge/Render/Connectors.hs:41:5: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding:
-        Patterns of type ‘(Maybe Float, Maybe Float)’ not matched:
-            (Nothing, _)
-            ((Just _), Nothing)
-   |
-41 |     (Just ymin,Just ymax) = minAndMax $ y : map (^._y) sps
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-/home/justin/Haskell/loop/src/Dodge/Particle/Draw.hs:15:5: warning: [GHC-62161] [-Wincomplete-uni-patterns]
-    Pattern match(es) are non-exhaustive
-    In a pattern binding:
-        Patterns of type ‘[Geometry.Data.Point2]’ not matched: []
-   |
-15 |     (sp : ps) = _lzPoints pt
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 /home/justin/Haskell/loop/src/Polyhedra.hs:68:5: warning: [GHC-62161] [-Wincomplete-uni-patterns]
     Pattern match(es) are non-exhaustive
     In a pattern binding:
@@ -142,6 +48,31 @@
     |
 302 |     (x : xs) = w ^. wCam . camBoundBox
     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+/home/justin/Haskell/loop/src/RandomHelp.hs:36:9: warning: [GHC-62161] [-Wincomplete-uni-patterns]
+    Pattern match(es) are non-exhaustive
+    In a pattern binding:
+        Patterns of type ‘([a], [a])’ not matched: (_, [])
+   |
+36 |     let (zs, w : ws) = splitAt i ys
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+/home/justin/Haskell/loop/src/RandomHelp.hs:51:17: warning: [GHC-62161] [-Wincomplete-uni-patterns]
+    Pattern match(es) are non-exhaustive
+    In a pattern binding:
+        Patterns of type ‘([b], [b])’ not matched: (_, [])
+   |
+51 |             let (as, b : bs) = splitAt rand ys
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+/home/justin/Haskell/loop/src/Dodge/HeldUse.hs:177:5: warning: [GHC-62161] [-Wincomplete-uni-patterns]
+    Pattern match(es) are non-exhaustive
+    In a pattern binding:
+        Patterns of type ‘([Float], StdGen)’ not matched:
+            ([], _)
+            ([_], _)
+            ([_, _], _)
+            ([_, _, _], _)
+    |
+177 |     (a : b : c : d : _, g) = runState thestate $ _randGen w -- randomRs (2, 20) (_randGen w)
+    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 /home/justin/Haskell/loop/src/Tile.hs:36:5: warning: [GHC-62161] [-Wincomplete-uni-patterns]
     Pattern match(es) are non-exhaustive
     In a pattern binding:
@@ -151,3 +82,24 @@
    |
 36 |     (c:d:_) = poly
    |     ^^^^^^^^^^^^^^
+/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:54:22: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
+    The prefix use of a ‘$’ would denote an untyped splice
+      were the TemplateHaskell extension enabled.
+    Suggested fix: Add whitespace after the ‘$’.
+   |
+54 |         shuffleLinks $(roomRectAutoLinks w h){_rmPmnts = []}
+   |                      ^
+/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:120:44: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
+    The prefix use of a ‘$’ would denote an untyped splice
+      were the TemplateHaskell extension enabled.
+    Suggested fix: Add whitespace after the ‘$’.
+    |
+120 |     let n = length $ filter bottomEdgeTest $_rmLinks centralRoom
+    |                                            ^
+/home/justin/Haskell/loop/src/Dodge/Room/RezBox.hs:122:29: warning: [GHC-47082] [-Woperator-whitespace-ext-conflict]
+    The prefix use of a ‘$’ would denote an untyped splice
+      were the TemplateHaskell extension enabled.
+    Suggested fix: Add whitespace after the ‘$’.
+    |
+122 |         tToBTree "rezBoxes" $treeFromTrunk [rezBox thecol, door] $
+    |                             ^

src/Dodge/Particle/Draw.hs

@@ -1,15 +0,0 @@
-module Dodge.Particle.Draw where
-
-import Dodge.Data.Laser
-import Picture
-
-drawTargetLaser :: Laser -> Picture
-drawTargetLaser pt =
-    setLayer BloomNoZWrite $
-        fold
-            [ setDepth 19 . color (brightX 0 0.5 col) $ thickLine 5 (sp : ps)
-            , setDepth 19.5 . color (brightX 5 1 col) $ thickLine 1 (sp : ps)
-            ]
-  where
-    col = _lzColor pt
-    (sp : ps) = _lzPoints pt

src/Dodge/Placement/PlaceSpot.hs

@@ -1,3 +1,4 @@
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
 {- | deals with placement of objects within the world
  after they have had their coordinates set by the layout
 -}
@@ -5,7 +6,6 @@ module Dodge.Placement.PlaceSpot (
     placeSpot,
 ) where
 
-import NewInt
 import Color
 import Control.Lens
 import Control.Monad.State
@@ -22,6 +22,7 @@ import Dodge.Placement.Shift
 import Dodge.ShiftPoint
 import Geometry
 import qualified IntMapHelp as IM
+import NewInt
 import Picture
 import System.Random
 
@@ -30,7 +31,8 @@ import System.Random
 placeSpot :: (GenWorld, Room) -> Placement -> ((GenWorld, Room), [Placement])
 placeSpot (w, rm) plmnt = case plmnt of
     Placement{_plSpot = PSRoomRand i f} -> placeSpotRoomRand rm i f plmnt w
-    Placement{_plSpot = PSPos extract eff fallback} -> placeSpotUsingLink w rm plmnt extract eff fallback
+    Placement{_plSpot = PSPos extract eff fallback} ->
+        placeSpotUsingLink w rm plmnt extract eff fallback
     Placement{} -> placePlainPSSpot w rm plmnt shift
     PlacementUsingPos p subpl -> placeSpot (w, rm) (subpl (shiftPoint3By shift p))
     RandomPlacement rplmnt -> placeRandomPlacement rplmnt w rm
@@ -39,14 +41,23 @@ placeSpot (w, rm) plmnt = case plmnt of
     shift = _rmShift rm
 
 placePickOne :: Int -> Placement -> Room -> GenWorld -> GenWorld
-placePickOne i pl rm w = w & genPlacements %~ IM.insertWith (++) i [(pl, fromJust (_rmMID rm))]
+placePickOne i pl rm = genPlacements %~ IM.insertWith (++) i [(pl, fromJust (_rmMID rm))]
 
-placeRandomPlacement :: State StdGen Placement -> GenWorld -> Room -> ((GenWorld, Room), [Placement])
+placeRandomPlacement ::
+    State StdGen Placement ->
+    GenWorld ->
+    Room ->
+    ((GenWorld, Room), [Placement])
 placeRandomPlacement rplmnt w rm = placeSpot (w & gwWorld . randGen .~ g, rm) plmnt'
   where
     (plmnt', g) = runState rplmnt (_randGen (_gwWorld w))
 
-placePlainPSSpot :: GenWorld -> Room -> Placement -> DPoint2 -> ((GenWorld, Room), [Placement])
+placePlainPSSpot ::
+    GenWorld ->
+    Room ->
+    Placement ->
+    DPoint2 ->
+    ((GenWorld, Room), [Placement])
 placePlainPSSpot w rm plmnt shift =
     let (i, w') = placeSpotID (shiftPSBy shift (_plSpot plmnt)) (_plType plmnt) w
         newplmnt = plmnt & plMID ?~ i
@@ -100,8 +111,12 @@ placeSpotID' ps pt w = case pt of
     PutProp prp -> plNewUpID (cWorld . lWorld . props) prID (mvProp p rot prp) w
     PutButton bt -> plNewUpID (cWorld . lWorld . buttons) btID (mvButton p rot bt) w
     PutTerminal tm -> plNewUpID (cWorld . lWorld . terminals) tmID tm w
-    PutFlIt itm -> plNewUpID (cWorld . lWorld . floorItems . unNIntMap) (flItID . unNInt) 
+    PutFlIt itm ->
-        (createFlIt p rot itm) w
+        plNewUpID
+            (cWorld . lWorld . floorItems . unNIntMap)
+            (flItID . unNInt)
+            (createFlIt p rot itm)
+            w
     PutCrit cr -> plNewUpID (cWorld . lWorld . creatures) crID (mvCr p rot cr) w
     PutForeground fs -> plNewUpID (cWorld . lWorld . foregroundShapes) fsID (mvFS p rot fs) w
     PutDecoration pic -> plNewID (cWorld . lWorld . decorations) (shiftDec p rot pic) w
@@ -134,7 +149,7 @@ placeSpotID' ps pt w = case pt of
     doShift = shiftPointBy (p, rot)
 
 shiftDec :: Point2 -> Float -> Picture -> Picture
-shiftDec p r pic = uncurryV translate p $ rotate r pic
+shiftDec p r = uncurryV translate p . rotate r
 
 evaluateRandPS :: State StdGen PSType -> PlacementSpot -> World -> (Int, World)
 evaluateRandPS rgen ps w = placeSpotID' ps evaluatedType (set randGen g w)
@@ -147,12 +162,8 @@ evaluateRandPS rgen ps w = placeSpotID' ps evaluatedType (set randGen g w)
 ----  where
 ----    rmCrossPaths w = foldr (uncurry obstructPathsCrossing) w $ loopPairs ps
 
---placeWalls :: [Point2] -> Wall -> IM.IntMap Wall -> IM.IntMap Wall
+-- this function is the reason for the warning suppression
---placeWalls qs wl wls = foldl' (addPane wl) wls pairs
+-- remove the warning suppression if it changes
---  where
---    (p:ps) = orderPolygon qs
---    pairs = zip (ps ++ [p]) (p:ps)
-
 placeWallPoly :: [Point2] -> Wall -> World -> World
 placeWallPoly qs wl w = foldl' (addPane wl) w pairs
   where
@@ -160,14 +171,10 @@ placeWallPoly qs wl w = foldl' (addPane wl) w pairs
     pairs = zip (ps ++ [p]) (p : ps)
 
 addPane :: Wall -> World -> (Point2, Point2) -> World
---addPane wl w l = w & walls %~ IM.insert wlid (wl { _wlLine = l, _wlID = wlid })
 addPane wl w l =
     w & plNew (cWorld . lWorld . walls) wlID (wl & wlLine .~ l)
         & fst . uncurry (obstructPathsCrossing WallObstacle) l
 
---  where
---    wlid = IM.newKey (_walls w)
-
 mvProp :: Point2 -> Float -> Prop -> Prop
 mvProp p a = (prRot +~ a) . (prPos %~ ((p +.+) . rotateV a))
 

src/Dodge/Render/Connectors.hs

@@ -1,42 +1,56 @@
-module Dodge.Render.Connectors
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-    ( zConnect
+
-    , zConnectCol
+module Dodge.Render.Connectors (
-    , lConnect
+    zConnect,
-    , lConnectMulti
+    zConnectCol,
-    ) where
+    lConnect,
-import FoldableHelp
+    lConnectMulti,
-import Picture
+) where
-import Geometry
+
 import Control.Lens
+import FoldableHelp
+import Geometry
 import Linear.V2
+import Picture
 
 zConnect :: Point2 -> Point2 -> Picture
-zConnect (V2 x y) (V2 a b) = line $ map toV2
+zConnect (V2 x y) (V2 a b) =
-    [(x,y)
+    line $
-    ,(0.5 * (x+a), y)
+        map
-    ,(0.5 * (x+a), b)
+            toV2
-    ,(a, b)
+            [ (x, y)
+            , (0.5 * (x + a), y)
+            , (0.5 * (x + a), b)
+            , (a, b)
             ]
+
 zConnectCol :: Point2 -> Point2 -> Color -> Color -> Color -> Color -> Picture
-zConnectCol (V2 x y) (V2 a b) c1 c2 c3 c4 = lineCol $ zip
+zConnectCol (V2 x y) (V2 a b) c1 c2 c3 c4 =
-    ( map toV2
+    lineCol $
-    [(x,y)
+        zip
-    ,(0.5 * (x+a), y)
+            ( map
-    ,(0.5 * (x+a), b)
+                toV2
-    ,(a, b)
+                [ (x, y)
+                , (0.5 * (x + a), y)
+                , (0.5 * (x + a), b)
+                , (a, b)
                 ]
-    ) [c1,c2,c3,c4]
+            )
+            [c1, c2, c3, c4]
 
 lConnect :: Point2 -> Point2 -> Picture
-lConnect sp@(V2 _ y) ep@(V2 x _) = line 
+lConnect sp@(V2 _ y) ep@(V2 x _) =
+    line
         [ sp
         , V2 x y
         , ep
         ]
 
+-- this function is the reason for the incomplete-uni-patterns warning suppression
 lConnectMulti :: [Point2] -> Point2 -> Picture
-lConnectMulti sps (V2 x y) = line [V2 x ymin,V2 x ymax] <>
+lConnectMulti sps (V2 x y) =
-    foldMap f sps
+    line [V2 x ymin, V2 x ymax]
+        <> foldMap f sps
   where
-    (Just ymin,Just ymax) = minAndMax $ y : map (^._y) sps
+    (Just ymin, Just ymax) = minAndMax $ y : map (^. _y) sps
-    f (V2 x' y') = line [V2 x' y',V2 x y']
+    f (V2 x' y') = line [V2 x' y', V2 x y']

src/Dodge/Update.hs

@@ -316,7 +316,7 @@ updateMouseInventorySelection' sss cfig w
         Just (MouseInvChosen ssel esel)
             | maybe False (>esel) $ inverseSelBoundaryDown cfig ldp sss mpos -> w
                 & shiftInvItemsDown ssel esel (inverseSelBoundaryDown cfig ldp sss mpos)
-        Just (MouseInvChosen ssel esel) -> w
+        Just (MouseInvChosen{}) -> w
         _ -> w
             & hud . hudElement . subInventory . nsSelected .~ NoMouseSel
     | otherwise = case w ^? hud . hudElement . subInventory . nsSelected of
@@ -338,7 +338,7 @@ updateMouseInventorySelection' sss cfig w
     mysel = inverseSelSecYint (posSelSecYint cfig ldp (mpos ^. _y)) sss
 
 shiftInvItemsUp :: (Int,Int) -> (Int,Int) -> Maybe (Int,Int) -> World -> World
-shiftInvItemsUp (_,i) (_,j) (Just (_,k)) w = w
+shiftInvItemsUp (_,i) (_,j) Just{} w = w
     & flip (foldl' f) [i..j]
     & hud . hudElement . subInventory . nsSelected . misChosenStart . _2 -~ 1
     & hud . hudElement . subInventory . nsSelected . misChosenEnd . _2 -~ 1
@@ -348,7 +348,7 @@ shiftInvItemsUp (_,i) (_,j) (Just (_,k)) w = w
 shiftInvItemsUp _ _ Nothing w = w
 
 shiftInvItemsDown :: (Int,Int) -> (Int,Int) -> Maybe (Int,Int) -> World -> World
-shiftInvItemsDown (_,i) (_,j) (Just (_,k)) w = w
+shiftInvItemsDown (_,i) (_,j) Just{} w = w
     & flip (foldl' f) (reverse [i..j])
     & hud . hudElement . subInventory . nsSelected . misChosenStart . _2 +~ 1
     & hud . hudElement . subInventory . nsSelected . misChosenEnd . _2 +~ 1

src/Multiset.hs

@@ -1,16 +1,19 @@
 {-# LANGUAGE TupleSections #-}
+{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
+
 module Multiset where
+
+import Control.Monad
+import qualified Data.IntSet as IS
 import qualified Data.Map.Strict as M
 import qualified IntMapHelp as IM
-import qualified Data.IntSet as IS
-import Control.Monad
 
 -- naive solution
-powlistUpToN' :: Int -> [a] ->[[a]]
+powlistUpToN' :: Int -> [a] -> [[a]]
 powlistUpToN' _ [] = [[]]
-powlistUpToN' n (x:xs) 
+powlistUpToN' n (x : xs)
-    | n <=0     = [[]]
+    | n <= 0 = [[]]
-    | otherwise = ((x:) <$> powlistUpToN' (n-1) xs) ++ powlistUpToN' n xs
+    | otherwise = ((x :) <$> powlistUpToN' (n -1) xs) ++ powlistUpToN' n xs
 
 -- adapted from
 -- https://stackoverflow.com/questions/21265454/subsequences-of-length-n-from-list-performance/59932616#59932616
@@ -18,47 +21,51 @@ powlistUpToN' n (x:xs)
 -- there is a (probably) faster SO answer that produces power lists of size
 -- exactly N, but that answer is harder to adapt
 powlistUpToN :: Int -> [a] -> [[a]]
-powlistUpToN n xs = concat $ drop (length xs-n) (subseqsBySize xs)
+powlistUpToN n xs = concat $ drop (length xs - n) (subseqsBySize xs)
   where
     subseqsBySize [] = [[[]]]
-    subseqsBySize (y:ys) =
+    subseqsBySize (y : ys) =
         let next = subseqsBySize ys
-        in zipWith (++) ([]:next) (map (map (y:)) next ++ [[]])
+         in zipWith (++) ([] : next) (map (map (y :)) next ++ [[]])
+
 powlistUpToN'' :: Int -> [a] -> [[a]]
 powlistUpToN'' n xs =
     let l = length xs
---    in if n > l then [] else concat $ drop (l-n) (subseqsBySize xs)
+     in --    in if n > l then [] else concat $ drop (l-n) (subseqsBySize xs)
-    in if n > l 
+        if n > l
             then concat $ subseqsBySize xs
-        else concat $ drop (l-n) (subseqsBySize xs)
+            else concat $ drop (l - n) (subseqsBySize xs)
   where
     subseqsBySize [] = [[[]]]
-    subseqsBySize (y:ys) =
+    subseqsBySize (y : ys) =
         let next = subseqsBySize ys
-        in zipWith (++) ([]:next) (map (map (y:)) next ++ [[]])
+         in zipWith (++) ([] : next) (map (map (y :)) next ++ [[]])
+
 -- this is the code producing all exactly n length sublists
+-- it is the reason for the incomplete-uni-patterns warning suppression
 combinationsOf :: Int -> [a] -> [[a]]
 combinationsOf 1 as = map pure as
-combinationsOf k' as@(_:xs) = run (l-1) (k'-1) as $ combinationsOf (k'-1) xs
+combinationsOf k' as@(_ : xs) = run (l -1) (k' -1) as $ combinationsOf (k' -1) xs
   where
     l = length as
     run :: Int -> Int -> [a] -> [[a]] -> [[a]]
     run n k ys cs
         | n == k = map (ys ++) cs
-        | otherwise = map (q:) cs ++ run (n-1) k qs (drop dc cs)
+        | otherwise = map (q :) cs ++ run (n -1) k qs (drop dc cs)
       where
-        (q:qs) = take (n-k+1) ys
+        (q : qs) = take (n - k + 1) ys
-        dc     = product [(n-k+1)..(n-1)] `div` product [1..(k-1)]
+        dc = product [(n - k + 1) .. (n -1)] `div` product [1 .. (k -1)]
 combinationsOf _ [] = []
 
 -- exponential, so don't use it on long lists
 powlist :: [a] -> [[a]]
-powlist = filterM (const [True,False])
+powlist = filterM (const [True, False])
 
 toMultiset :: Ord a => [a] -> M.Map a Int
-toMultiset = foldr (uncurry (M.insertWith (+)) . (, 1)) M.empty
+toMultiset = foldr (uncurry (M.insertWith (+)) . (,1)) M.empty
 
 invertIntMap :: Ord a => IM.IntMap a -> M.Map a IS.IntSet
-invertIntMap = IM.foldrWithKey 
+invertIntMap =
+    IM.foldrWithKey
         (\k x -> M.insertWith IS.union x (IS.singleton k))
         M.empty