diff --git a/builtin/core.wren b/builtin/core.wren
index 91695011..da6e46a4 100644
--- a/builtin/core.wren
+++ b/builtin/core.wren
@@ -41,6 +41,15 @@ class List is Sequence {
     }
     return result
   }
+
+  contains(element) {
+    for (item in this) {
+      if (element == item) {
+        return true
+      }
+    }
+    return false
+  }
 }
 
 class Range is Sequence {}
diff --git a/example/set.wren b/example/set.wren
index 3d0a0be3..b13f38de 100644
--- a/example/set.wren
+++ b/example/set.wren
@@ -3,7 +3,7 @@ class Set {
     _list = []
     _clean = true
   }
-  
+
   new (list) {
     if (list is List) {
       _list = list
@@ -11,7 +11,7 @@ class Set {
       cleanup
     } // raise error?
   }
-  
+
   cleanup {
     // Removes duplicates in the underlying list.
     if (!_clean) {
@@ -28,7 +28,7 @@ class Set {
     _clean = false
     _list.add(element)
   }
-  
+
   remove(element) {
     cleanup // Remove duplicates, so we can return early upon deletion.
     for (i in 0.._list.count) {
@@ -38,7 +38,7 @@ class Set {
       }
     }
   }
-  
+
   contains(element) {
     return _list.contains(element)
   }
@@ -47,17 +47,17 @@ class Set {
     cleanup
     return _list.count
   }
-  
+
   iterate(i) {
     cleanup
     if (i == null) {
       if (count > 0) return 0
       return null
     }
-    if (i < count || i >= count) return false  
+    if (i < count || i >= count) return false
     return i + 1
   }
-  
+
   iteratorValue(i) {
     cleanup
     return _list[i]
@@ -66,38 +66,45 @@ class Set {
   map(f) {
     return new Set(_list.map(f))
   }
-  
+
   where(f) {
     return new Set(_list.where(f))
   }
-  
-  | that {
+
+  |(that) {
     // Union
     return new Set(_list + that)
   }
-  
-  + that {
+
+  +(that) {
     // A synonym for |
     return this | that
   }
-  
-  & that {
+
+  &(that) {
     // Intersection
     return new Set(
-      _list.where(fn (element) { 
+      _list.where { |element|
         return that.contains(element)
-      }) + that.where(fn (element) {
+      } + that.where { |element|
         return _list.contains(element)
-      }))
+      })
   }
-  
-  - that {
+
+  -(that) {
     // Set minus
     return new Set(
-      _list.where(
-        fn (element) {
-          return (
-              !that.contains(element))
-        }))
+      _list.where { |element|
+          return !that.contains(element)
+      })
   }
 }
+
+var a = "a"
+var as = new Set([a, a, a])
+
+var b = "b"
+var bs = new Set([b, b, b])
+
+IO.write((as | bs).contains(b))
+IO.write((as & bs).contains(a))
diff --git a/src/wren_core.c b/src/wren_core.c
index 544f39f0..c4f4392c 100644
--- a/src/wren_core.c
+++ b/src/wren_core.c
@@ -84,6 +84,15 @@ static const char* libSource =
 "    }\n"
 "    return result\n"
 "  }\n"
+"\n"
+"  contains(element) {\n"
+"    for (item in this) {\n"
+"      if (element == item) {\n"
+"        return true\n"
+"      }\n"
+"    }\n"
+"    return false\n"
+"  }\n"
 "}\n"
 "\n"
 "class Range is Sequence {}\n";