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diff --git a/docs/examples/parsing/lambda/TestSyntax.scala b/docs/examples/parsing/lambda/TestSyntax.scala
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+++ b/docs/examples/parsing/lambda/TestSyntax.scala
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+package examples.parsing.lambda
+
+/**
+ * Parser for an untyped lambda calculus: abstract syntax tree
+ *
+ * @author Miles Sabin (adapted slightly by Adriaan Moors)
+ */
+trait TestSyntax
+{
+  trait Term
+
+  case class Unit extends Term
+  {
+    override def toString = "unit"
+  }
+
+  case class Lit(n: int) extends Term
+  {
+    override def toString = n.toString
+  }
+
+  case class Bool(b: boolean) extends Term
+  {
+    override def toString = b.toString
+  }
+
+  case class Name(name: String) extends Term
+  {
+    override def toString = name
+  }
+
+  case class Ref(n: Name) extends Term
+  {
+    def value = n
+  }
+
+  case class Lam(n: Name, l: Term) extends Term
+  {
+    override def toString = "(\\ "+n+" -> "+l+")"
+  }
+
+  case class App(t1: Term, t2: Term) extends Term
+  {
+    override def toString = "("+t1+" "+t2+")"
+  }
+
+  case class Let(n: Name, t1: Term, t2: Term) extends Term
+  {
+    override def toString = "let "+n+" = "+t1+" in "+t2
+  }
+
+  case class If(c: Term, t1: Term, t2: Term) extends Term
+  {
+    override def toString = "if "+c+" then "+t1+" else "+t2
+  }
+
+  trait PrimTerm extends Term
+  {
+    def apply(n: Lit) : Term
+  }
+
+  case class PrimPlus extends PrimTerm
+  {
+    def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n+y.n) }
+  }
+
+  case class PrimMinus extends PrimTerm
+  {
+    def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n-y.n) }
+  }
+
+  case class PrimMultiply extends PrimTerm
+  {
+    def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n*y.n) }
+  }
+
+  case class PrimDivide extends PrimTerm
+  {
+    def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Lit(x.n/y.n) }
+  }
+
+  case class PrimEquals extends PrimTerm
+  {
+    def apply(x: Lit) = new PrimTerm { def apply(y: Lit) = Bool(x.n == y.n) }
+  }
+}