Finish draft of post 8 in compiler series

code/compiler/08/examples/works1.txt

@@ -1,2 +1,2 @@
-defn main = { plus 320 6 }
-defn plus x y = { x + y }
+defn main = { sum 320 6 }
+defn sum x y = { x + y }

code/compiler/08/examples/works3.txt

@@ -5,3 +5,4 @@ defn length l = {
         Cons x xs -> { 1 + length xs }
     }
 }
+defn main = { length (Cons 1 (Cons 2 (Cons 3 Nil))) }

code/compiler/08/examples/works4.txt

@@ -0,0 +1,16 @@
+data List = { Nil, Cons Int List }
+
+defn add x y = { x + y }
+defn mul x y = { x * y }
+
+defn foldr f b l = {
+    case l of {
+        Nil -> { b }
+        Cons x xs -> { f x (foldr f b xs) }
+    }
+}
+
+defn main = {
+    foldr add 0 (Cons 1 (Cons 2 (Cons 3 (Cons 4 Nil)))) +
+    foldr mul 1 (Cons 1 (Cons 2 (Cons 3 (Cons 4 Nil))))
+}

code/compiler/08/examples/works5.txt

@@ -0,0 +1,17 @@
+data List = { Nil, Cons Int List }
+
+defn sumZip l m = {
+    case l of {
+        Nil -> { 0 }
+        Cons x xs -> {
+            case m of {
+                Nil -> { 0 }
+                Cons y ys -> { x + y + sumZip xs ys }
+            }
+        }
+    }
+}
+
+defn ones = { Cons 1 ones }
+
+defn main = { sumZip ones (Cons 1 (Cons 2 (Cons 3 Nil))) }