--- a/progs/fun/simple-cps.sc	Fri Jun 02 15:58:57 2023 +0100
+++ b/progs/fun/simple-cps.sc	Sun Jun 04 23:59:19 2023 +0100
@@ -23,6 +23,11 @@
 }
 import KExp._
 
+def pexp(e: KExp): String = e match {
+    case KReturn(v) => s"KReturn($v)"
+    case KLet(x,e1,e2) => s"KLet($x = ${e1} \n in ${pexp(e2)})"
+}
+
 var cnt = -1
 def Fresh(s: String) = {
     cnt = cnt + 1
@@ -60,4 +65,26 @@
                      Num(3), 
                      Call("id", List(Num(12))))))
 
-println(CPSi(etest))
+println(pexp(CPSi(etest)))
+
+// Constant Folding
+def opt(v: KVal, env: Map[String, Int]) : KVal = v match {
+    case KVar(s) => if (env.isDefinedAt(s)) KNum(env(s)) else KVar(s)
+    case KNum(n) => KNum(n)
+    case KAop(op, v1, v2) => (op, opt(v1, env), opt(v2, env)) match {
+        case ("+", KNum(n1), KNum(n2)) => KNum(n1 + n2)
+        case ("*", KNum(n1), KNum(n2)) => KNum(n1 * n2)
+        case (_, v1o, v2o) => KAop(op, v1o, v2o)
+    }
+    case KCall(fname, args) => KCall(fname, args.map(opt(_, env)))
+}
+    
+def Koptimise(ke: KExp, env: Map[String, Int] = Map()) : KExp = ke match {
+    case KReturn(v) => KReturn(opt(v, env)) 
+    case KLet(x, v, e) => opt(v, env) match {
+        case KNum(n) => Koptimise(e, env + (x -> n))
+        case vo => KLet(x, vo, Koptimise(e, env))
+    }
+}    
+
+println("\n" ++ pexp(Koptimise(CPSi(etest))))