Added example based on WhileLang.

This example is based on the WhileLang example used in SWEN430.
Specifically, this is a simple while language interpreter.  Currently,
it is not complete yet though.

Author: DavePearce

examples/whilelang/WhileLang.wyrl

@@ -0,0 +1,50 @@
+// ====================================================================
+// Values
+// ====================================================================
+term Num(int)
+term False
+term True
+define Bool as True|False
+define Value as Num | Bool
+
+// ====================================================================
+// Expressions
+// ====================================================================
+term Var(string)
+term Sub[Expr,Expr]
+term Add[Expr,Expr]
+term Mul[Expr,Expr]
+term Div[Expr,Expr]
+
+define Expr as Value | Var | Sub | Add | Mull | Div
+
+// ====================================================================
+// Statements
+// ====================================================================
+term Assign[Var,Expr]
+term Return(Expr)
+
+define Stmt as Assign | Return
+
+// ====================================================================
+// Semantics
+// ====================================================================
+term Env{[Var,Value]...}
+term Program[Stmt...]
+
+term State[Env,Program]
+
+// R-Return1
+reduce State[Env, Program[Return(Value v),Stmt... rest]]:
+     => v
+
+// R-Return2 ?
+
+// R-Assign1
+reduce State[Env{[Var,Value]... ps}, Program[Assign[Var v, Value n],Stmt... rest]]:
+    => let ws = { [p[0],p[1]] | p in ps, p[0] != v }
+       in State[Env(ws ++ {[v,n]}), rest]
+
+// R-Assign2 ?
+
+

examples/whilelang/build.xml

@@ -0,0 +1,17 @@
+<project name="wyrl" default="build">
+  <import file="../../config.xml"/>
+  
+  <target name="build">
+    <taskdef name="wyrl" classname="wyrl.util.WyrlAntTask" classpath="../../src/:../../${WYBS_JAR}"/>
+    <wyrl srcdir="." debug="false" source="WhileLang.wyrl" output="WhileLang.java"/>
+    <javac debug="true" debuglevel="vars,lines,source" srcdir="." source="1.7" target="1.7" includeantruntime="false" classpath="../../src/">
+      <include name="*/**"/>
+    </javac>
+  </target>
+
+ <target name="clean">
+   <delete failonerror="false">
+     <fileset dir="." includes="*.class,WhileLang.java"/>
+   </delete>
+ </target>
+</project>