Fix #107 - explicitly discard contexts

Author: paf31

exercises/chapter9/src/Example/LSystem.purs

@@ -51,13 +51,13 @@ main = void $ unsafePartial do
     interpret state F = do
       let x = state.x + Math.cos state.theta * 1.5
           y = state.y + Math.sin state.theta * 1.5
-      moveTo ctx state.x state.y
-      lineTo ctx x y
+      _ <- moveTo ctx state.x state.y
+      _ <- lineTo ctx x y
       pure { x, y, theta: state.theta }
 
     initialState :: State
     initialState = { x: 120.0, y: 200.0, theta: 0.0 }
 
-  setStrokeStyle "#000000" ctx
+  _ <- setStrokeStyle "#000000" ctx
 
   strokePath ctx $ lsystem initial productions interpret 5 initialState

exercises/chapter9/src/Example/Random.purs

@@ -17,8 +17,8 @@ main = void $ unsafePartial do
   Just canvas <- getCanvasElementById "canvas"
   ctx <- getContext2D canvas
 
-  setFillStyle "#FF0000" ctx
-  setStrokeStyle "#000000" ctx
+  _ <- setFillStyle "#FF0000" ctx
+  _ <- setStrokeStyle "#000000" ctx
 
   for_ (1 .. 100) \_ -> do
     x <- random
@@ -33,5 +33,5 @@ main = void $ unsafePartial do
          , end   : Math.pi * 2.0
          }
 
-    fillPath ctx path
+    _ <- fillPath ctx path
     strokePath ctx path

exercises/chapter9/src/Example/Rectangle.purs

@@ -13,7 +13,7 @@ main = void $ unsafePartial do
   Just canvas <- getCanvasElementById "canvas"
   ctx <- getContext2D canvas
 
-  setFillStyle "#0000FF" ctx
+  _ <- setFillStyle "#0000FF" ctx
 
   fillPath ctx $ rect ctx
     { x: 250.0

exercises/chapter9/src/Example/Refs.purs

@@ -16,27 +16,27 @@ import Graphics.Canvas (Context2D, CANVAS, getContext2D, getCanvasElementById,
 import Math as Math
 import Partial.Unsafe (unsafePartial)
 
-render :: forall eff. Int -> Context2D -> Eff (canvas :: CANVAS | eff) Context2D
-render count ctx = do
-  setFillStyle "#FFFFFF" ctx
+render :: forall eff. Int -> Context2D -> Eff (canvas :: CANVAS | eff) Unit
+render count ctx = void do
+  _ <- setFillStyle "#FFFFFF" ctx
 
-  fillPath ctx $ rect ctx
+  _ <- fillPath ctx $ rect ctx
     { x: 0.0
     , y: 0.0
     , w: 600.0
     , h: 600.0
     }
 
-  setFillStyle "#00FF00" ctx
+  _ <- setFillStyle "#00FF00" ctx
 
   withContext ctx do
     let scaleX = Math.sin (toNumber count * Math.pi / 4.0) + 1.5
     let scaleY = Math.sin (toNumber count * Math.pi / 6.0) + 1.5
 
-    translate { translateX: 300.0, translateY:  300.0 } ctx
-    rotate (toNumber count * Math.pi / 18.0) ctx
-    scale { scaleX: scaleX, scaleY: scaleY } ctx
-    translate { translateX: -100.0, translateY: -100.0 } ctx
+    _ <- translate { translateX: 300.0, translateY:  300.0 } ctx
+    _ <- rotate (toNumber count * Math.pi / 18.0) ctx
+    _ <- scale { scaleX: scaleX, scaleY: scaleY } ctx
+    _ <- translate { translateX: -100.0, translateY: -100.0 } ctx
 
     fillPath ctx $ rect ctx
       { x: 0.0

exercises/chapter9/src/Example/Shapes.purs

@@ -26,29 +26,29 @@ main = void $ unsafePartial do
   Just canvas <- getCanvasElementById "canvas"
   ctx <- getContext2D canvas
 
-  setFillStyle "#0000FF" ctx
+  _ <- setFillStyle "#0000FF" ctx
 
-  fillPath ctx $ rect ctx $ translate (-200.0) (-200.0)
+  _ <- fillPath ctx $ rect ctx $ translate (-200.0) (-200.0)
     { x: 250.0
     , y: 250.0
     , w: 100.0
     , h: 100.0
     }
 
-  setFillStyle "#00FF00" ctx
+  _ <- setFillStyle "#00FF00" ctx
 
-  fillPath ctx $ arc ctx $ translate 200.0 200.0
+  _ <- fillPath ctx $ arc ctx $ translate 200.0 200.0
     { x: 300.0
     , y: 300.0
     , r: 50.0
     , start: Math.pi * 5.0 / 8.0
     , end: Math.pi * 2.0
     }
 
-  setFillStyle "#FF0000" ctx
+  _ <- setFillStyle "#FF0000" ctx
 
   fillPath ctx $ do
-    moveTo ctx 300.0 260.0
-    lineTo ctx 260.0 340.0
-    lineTo ctx 340.0 340.0
+    _ <- moveTo ctx 300.0 260.0
+    _ <- lineTo ctx 260.0 340.0
+    _ <- lineTo ctx 340.0 340.0
     closePath ctx