---

yaml
---
r: 27687
b: refs/heads/try
c: 8703d08
h: refs/heads/master
i:
  27685: d65784b
  27683: d960edc
  27679: 3e22d8d
v: v3

Author: lkuper

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
-refs/heads/try: e82d2ef7639252ba365427ea1ad0e285986b5bf8
+refs/heads/try: 8703d088ead97cff975187bcd5b57851ad410cbe
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/ndm: f3868061cd7988080c30d6d5bf352a5a5fe2460b
 refs/heads/try2: d0c6ce338884ee21843f4b40bf6bf18d222ce5df

branches/try/src/test/run-pass/typeclasses-eq-example.rs

@@ -0,0 +1,54 @@
+// Example from lkuper's intern talk, August 2012.
+
+trait Equal {
+    fn isEq(a: self) -> bool;
+}
+
+enum Color { cyan, magenta, yellow, black }
+
+impl Color : Equal {
+    fn isEq(a: Color) -> bool {
+        match (self, a) {
+          (cyan, cyan)       => { true  }
+          (magenta, magenta) => { true  }
+          (yellow, yellow)   => { true  }
+          (black, black)     => { true  }
+          _                  => { false }
+        }
+    }
+}
+
+enum ColorTree {
+    leaf(Color),
+    branch(@ColorTree, @ColorTree)
+}
+
+impl ColorTree : Equal {
+    fn isEq(a: ColorTree) -> bool {
+        match (self, a) {
+          (leaf(x), leaf(y)) => { x.isEq(y) }
+          (branch(l1, r1), branch(l2, r2)) => { 
+            (*l1).isEq(*l2) && (*r1).isEq(*r2)
+          }
+          _ => { false }
+        }
+    }
+}
+
+fn main() {
+    assert cyan.isEq(cyan);
+    assert magenta.isEq(magenta);
+    assert !cyan.isEq(yellow);
+    assert !magenta.isEq(cyan);
+
+    assert leaf(cyan).isEq(leaf(cyan));
+    assert !leaf(cyan).isEq(leaf(yellow));
+
+    assert branch(@leaf(magenta), @leaf(cyan))
+        .isEq(branch(@leaf(magenta), @leaf(cyan)));
+
+    assert !branch(@leaf(magenta), @leaf(cyan))
+        .isEq(branch(@leaf(magenta), @leaf(magenta)));
+
+    log(error, "Assertions all succeeded!");
+}