test case for unapply gadt evaluator

1 files changed, 35 insertions, 0 deletions

diff --git a/test/pending/pos/unappgadteval.scala b/test/pending/pos/unappgadteval.scala
new file mode 100644
index 0000000000..0c22c71dee
--- /dev/null
+++ b/test/pending/pos/unappgadteval.scala
@@ -0,0 +1,35 @@
+//Class hierarchy
+trait Term[a]
+object Var{ def unapply[a](x:Var[a]) = Some(x.name) }
+class Var[a] (val name : String) extends Term[a]
+object Num{ def unapply(x:Num) = Some(x.value) }
+class Num (val value : int) extends Term[int]
+object Lam{ def unapply[b,c](l:Lam[b,c]) = Some{l.x,l.e}}
+class Lam[b, c] (val x : Var[b], val e : Term[c]) extends Term[b => c]
+object App{ def unapply[b,c](a:App[b,c]) = Some{a.f,a.e}}
+class App[b, c] (val f : Term[b => c], val e : Term[b]) extends Term[c]
+object Suc{ def unapply(a:Suc) = true }
+class Suc () extends Term[int => int]
+// Environments :
+abstract class Env {
+  def apply[a](v : Var[a]): a
+  def extend[a](v : Var[a], x : a) = new Env {
+    def apply[b](w: Var[b]): b = w match {
+      case _ : v.type => x // v eq w, hence a = b
+      case _ => Env.this.apply(w)
+    }}
+}
+
+object empty extends Env {
+  def apply[a](x : Var[a]): a = throw new Error("not found : "+x.name)
+}
+object Test {
+// Evaluation :
+def eval[a](t : Term[a], env : Env): a = t match {
+  case v : Var[b]        => env(v)                     // a = b
+  case n @ Num(value)    => value                      // a = int
+  case i @ Suc()         => { y: int => y + 1 }       // a = int=>int
+  case f @ Lam[b,c](x,e) => { y: b   => eval(e, env.extend(x, y))}  // a = b=>c
+  case a @ App(f,e)      => eval(f, env)(eval(e, env)) // a = c
+}
+}