2 files changed, 53 insertions, 0 deletions
diff --git a/ex2/Main.hs b/ex2/Main.hs
new file mode 100644
index 0000000..7e32c4a
--- /dev/null
+++ b/ex2/Main.hs
@@ -0,0 +1,4 @@
+import Shape
+
+main = do
+  putStrLn $ show $ square 5.0
diff --git a/ex2/Shape.hs b/ex2/Shape.hs
new file mode 100644
index 0000000..0f7c0a9
--- /dev/null
+++ b/ex2/Shape.hs
@@ -0,0 +1,49 @@
+module Shape
+        ( Shape
+        , area
+        , square
+        , circle
+        )
+where
+
+data Shape = Rectangle Side Side
+           | Ellipse Radius Radius
+           | RtTriangle Side Side
+           | Polygon [Vertex]
+  deriving Show
+
+type Radius = Float
+type Side = Float
+type Vertex = (Float, Float)
+
+area :: Shape -> Float
+area (Rectangle  s1 s2) = s1 * s2
+area (RtTriangle s1 s2) = s1 * s2 / 2
+
+square :: Side -> Shape
+square s = Rectangle s s
+
+circle :: Radius -> Shape
+circle r = Ellipse r r
+
+rectangle :: Side -> Side -> Shape
+rectangle s1 s2 = Polygon [(x, y), (-x, y), (-x, -y), (x, -y)]
+    where
+        x = s1 / 2
+        y = s2 / 2
+
+rtTriangle :: Side -> Side -> Shape
+rtTriangle s1 s2 = Polygon [(0, 0), (s1, 0), (0, s2)]
+
+regularPolygon :: Int -> Side -> Shape
+regularPolygon n s =
+        let
+                angleinc = (pi * 2) / fromIntegral n
+                radius   = (s * sin ((pi - angleinc) / 2)) / (sin angleinc)
+                regularVerts 0 _ = []
+                regularVerts n angle =
+                        (radius * cos angle, radius * sin angle) : regularVerts
+                                (n - 1)
+                                (angle + angleinc)
+        in
+                Polygon (regularVerts n 0)