# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1362899450 0
# Node ID 18905d086cbbe21764bdacee855585b0218d558e
# Parent  262fc2c6371bd4bbfc6f8643f29f3337964faf84
some peephole optimisations in the scala code

diff -r 262fc2c6371b -r 18905d086cbb scala/abacus.scala
--- a/scala/abacus.scala	Fri Mar 08 11:31:04 2013 +0000
+++ b/scala/abacus.scala	Sun Mar 10 07:10:50 2013 +0000
@@ -35,16 +35,16 @@
     case Goto(l) => if (l == old_jump) Goto(jump) else Goto(l)
   }))
 
-  def step(cf: AConfig) : AConfig = (nth_of(p, cf.s), cf.s) match {
-    case (None, _) => cf
-    case (Some(Inc(n)), s) => AConfig(s + 1, cf.regs + (n -> (dget(cf.regs, n) + 1)))
-    case (Some(Dec(n, l)), s) => {
+  def step(cf: AConfig) : AConfig = nth_of(p, cf.s) match {
+    case None => cf
+    case Some(Inc(n)) => AConfig(cf.s + 1, cf.regs + (n -> (dget(cf.regs, n) + 1)))
+    case Some(Dec(n, l)) => {
       if (dget(cf.regs, n) == 0) AConfig(l, cf.regs)
-      else AConfig(s + 1, cf.regs + (n -> (dget(cf.regs, n) - 1)))
+      else AConfig(cf.s + 1, cf.regs + (n -> (dget(cf.regs, n) - 1)))
     }
-    case (Some(Goto(l)), _) => AConfig(l, cf.regs)
-  }  
-
+    case Some(Goto(l)) => AConfig(l, cf.regs)
+  } 
+  
   def steps(cf: AConfig, n: Int) : AConfig = n match {
     case 0 => cf
     case n => steps(step(cf), n - 1)
diff -r 262fc2c6371b -r 18905d086cbb scala/ex.scala
--- a/scala/ex.scala	Fri Mar 08 11:31:04 2013 +0000
+++ b/scala/ex.scala	Sun Mar 10 07:10:50 2013 +0000
@@ -90,8 +90,11 @@
 def test_comp2(f: Rec, ns: Int*) = {
   val (abc_f, arity, _) = compile_rec(f)
   val abc_map = (0 until ns.length).zip(ns).toMap[Int, Int]
+  val start = System.nanoTime()
   val res = (abc_f.run(abc_map))(arity)
-  ("Result: " + res + "  length: " + abc_f.p.length)
+  val end = System.nanoTime()
+  val time = (end - start)/1.0e9
+  ("Result: " + res + "  length: " + abc_f.p.length + " time: " + "%.5f".format(time))
 }
 
 println("S(3)          " + test_comp2(S, 3))
@@ -102,7 +105,7 @@
 println("Power(3, 4)   " + test_comp2(Power, 3, 4))
 println("Minus(30, 4)  " + test_comp2(Minus, 30, 4))
 println("Fact(5)       " + test_comp2(Fact, 5))
-//println("Prime(5)      " + test_comp2(Prime, 5))
+println("Prime(5)      " + test_comp2(Prime, 5))
 //println("Prime(4)      " + test_comp2(Prime, 4))
 println("Strt(1)(2)    " + test_comp2(Strt(1), 2))
 
@@ -110,8 +113,11 @@
 def test_comp1(f: Rec, ns: Int*) = {
   val (abc_f, arity, _) = compile_rec(f)
   val tm = toTM(abc_f.p) :+ TMMopup(arity)
+  val start = System.nanoTime()
   val res = tm.run(Tape(ns.toList))
-  ("length: " + tm.p.length + " tape: " + arity + "\nResult: " + res)
+  val end = System.nanoTime()
+  val time = (end - start)/1.0e9
+  ("length: " + tm.p.length + " tape: " + arity + " time: " + "%.5f".format(time) + "\nResult: " + res)
 }
 
 println("")
diff -r 262fc2c6371b -r 18905d086cbb scala/lib.scala
--- a/scala/lib.scala	Fri Mar 08 11:31:04 2013 +0000
+++ b/scala/lib.scala	Sun Mar 10 07:10:50 2013 +0000
@@ -1,15 +1,23 @@
 package object lib {
 
 //some list functions
-def tl[A](xs: List[A]) : List[A] = xs match {
-  case Nil => Nil
-  case x::xs => xs
-}
+//slow version
+//def tl[A](xs: List[A]) : List[A] = xs match {
+//  case Nil => Nil
+//  case x::xs => xs
+//}
+
+def tl[A](xs: List[A]) : List[A] = 
+  try { xs.tail } catch { case _:UnsupportedOperationException => Nil }
 
 def hd[A](xs: List[A]) : A = xs.head
 
+//slow version
+//def nth_of[A](xs: List[A], n: Int) = 
+//  if (n <= xs.length) Some(xs(n)) else None 
+
 def nth_of[A](xs: List[A], n: Int) = 
-  if (n <= xs.length) Some(xs(n)) else None 
+  try { Some(xs(n)) } catch { case _:IndexOutOfBoundsException => None }
 
 //some map functions
 def dget(m: Map[Int, Int], n: Int) = m.getOrElse(n, 0)