unsafePerformIO houghLinesP

I'm sure there's a good reason it's in Prim,
but I don't have time right now.

src/TilePositioner.hs

@@ -13,6 +13,7 @@ import OpenCV as CV
 import OpenCV.Extra.XFeatures2d
 import OpenCV.Internal.C.Types
 import OpenCV.ImgProc.FeatureDetection
+import System.IO.Unsafe ( unsafePerformIO )
 
 import Loop
 import Track
@@ -48,8 +49,8 @@ type EdgeMat = Mat ('S ['D, 'D]) ('S 1) ('S Word8)
 edges :: FrameMat -> EdgeMat
 edges frame = exceptError $ canny 30 200 Nothing CannyNormL1 frame
 
-lines :: (PrimMonad m) => FrameMat -> m (Vector (LineSegment Int32))
-lines frame = do
+lines :: FrameMat -> Vector (LineSegment Int32)
+lines frame = unsafePerformIO $ do
   imgM <- CV.thaw (edges frame)
   exceptErrorM $ houghLinesP 1 (pi / 180) 80 (Just 30) (Just 10) imgM
 

src/TilePositionerDebug.hs

@@ -37,7 +37,7 @@ showHough t frame = exceptError $ do
   let [h, w] = miShape . matInfo $ frame
   withMatM (h ::: w ::: Z) (Proxy :: Proxy 3) (Proxy :: Proxy Word8) white $ \imgM -> do
       void $ matCopyToM imgM zero edgesBgr Nothing
-      lines' <- lines frame
+      let lines' = lines frame
       for_  lines' $ \lineSegment -> line imgM (lineSegmentStart lineSegment) (lineSegmentStop  lineSegment) red 2 LineType_8 0
 
       imgG <- cvtColor bgr gray frame

test/Spec.hs

@@ -163,7 +163,7 @@ tilePositionerMinRadius =
 
 tilePositionerLines :: Assertion
 tilePositionerLines = do
-  tpLines <- TP.lines idleNoCarsRotated
+  let tpLines = TP.lines idleNoCarsRotated
   V.length tpLines @?= 38
 
 tilePositionerCircles :: Assertion