Upgrade to a simulation

Main.hs

@@ -4,12 +4,21 @@
 module Main (main) where
 
 import Graphics.Gloss
+import Graphics.Gloss.Geometry.Angle
+
+data PolarCoord = PolarCoord { radius :: Float, angle :: Float }
+
+render :: PolarCoord -> Picture
+render state = pictures [ circleSolid 10, translatePolar state $ circleSolid 10 ]
+
+step :: a -> b -> PolarCoord -> PolarCoord
+step _ _ state = state { angle = normalizeAngle $ angle state + pi / 50 }
+
+translatePolar :: PolarCoord -> Picture -> Picture
+translatePolar q = rotate (radToDeg $ angle q) . translate (radius q) 0
 
 window :: Display
 window = InWindow "Foo" (200, 200) (100, 100)
 
-frame :: Float -> Picture
-frame t = rotate (100 * t) $ rectangleSolid 80 80
-
 main :: IO ()
-main = animate window white frame
+main = simulate window white 100 (PolarCoord 80 0) render step