diff --git a/sets/treeset/treeset.go b/sets/treeset/treeset.go
index 42d0eee..25acbcf 100644
--- a/sets/treeset/treeset.go
+++ b/sets/treeset/treeset.go
@@ -33,6 +33,7 @@ import (
 
 func assertInterfaceImplementation() {
 	var _ sets.Set = (*Set)(nil)
+	var _ containers.Enumerable = (*Set)(nil)
 	var _ containers.IteratorWithIndex = (*Iterator)(nil)
 }
 
@@ -71,7 +72,7 @@ func (set *Set) Remove(items ...interface{}) {
 	}
 }
 
-// Check wether items (one or more) are present in the set.
+// Check weather items (one or more) are present in the set.
 // All items have to be present in the set for the method to return true.
 // Returns true if no arguments are passed at all, i.e. set is always superset of empty set.
 func (set *Set) Contains(items ...interface{}) bool {
@@ -125,6 +126,63 @@ func (iterator *Iterator) Index() int {
 	return iterator.index
 }
 
+func (set *Set) Each(f func(index interface{}, value interface{})) {
+	iterator := set.Iterator()
+	for iterator.Next() {
+		f(iterator.Index(), iterator.Value())
+	}
+}
+
+func (set *Set) Map(f func(index interface{}, value interface{}) interface{}) containers.Container {
+	newSet := &Set{tree: rbt.NewWith(set.tree.Comparator)}
+	iterator := set.Iterator()
+	for iterator.Next() {
+		newSet.Add(f(iterator.Index(), iterator.Value()))
+	}
+	return newSet
+}
+
+func (set *Set) Select(f func(index interface{}, value interface{}) bool) containers.Container {
+	newSet := &Set{tree: rbt.NewWith(set.tree.Comparator)}
+	iterator := set.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
+			newSet.Add(iterator.Value())
+		}
+	}
+	return newSet
+}
+
+func (set *Set) Any(f func(index interface{}, value interface{}) bool) bool {
+	iterator := set.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
+			return true
+		}
+	}
+	return false
+}
+
+func (set *Set) All(f func(index interface{}, value interface{}) bool) bool {
+	iterator := set.Iterator()
+	for iterator.Next() {
+		if !f(iterator.Index(), iterator.Value()) {
+			return false
+		}
+	}
+	return true
+}
+
+func (set *Set) Find(f func(index interface{}, value interface{}) bool) (index interface{}, value interface{}) {
+	iterator := set.Iterator()
+	for iterator.Next() {
+		if f(iterator.Index(), iterator.Value()) {
+			return iterator.Index(), iterator.Value()
+		}
+	}
+	return nil, nil
+}
+
 func (set *Set) String() string {
 	str := "TreeSet\n"
 	items := []string{}
diff --git a/sets/treeset/treeset_test.go b/sets/treeset/treeset_test.go
index 780a9db..78f1e3a 100644
--- a/sets/treeset/treeset_test.go
+++ b/sets/treeset/treeset_test.go
@@ -84,11 +84,100 @@ func TestTreeSet(t *testing.T) {
 	}
 }
 
-func TestTreeSetIterator(t *testing.T) {
+func TestTreeSetEnumerableAndIterator(t *testing.T) {
 	set := NewWithStringComparator()
-	set.Add("c")
-	set.Add("a")
-	set.Add("b")
+	set.Add("c", "a", "b")
+
+	// Each
+	set.Each(func(index interface{}, value interface{}) {
+		switch index {
+		case 0:
+			if actualValue, expectedValue := value, "a"; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		case 1:
+			if actualValue, expectedValue := value, "b"; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		case 2:
+			if actualValue, expectedValue := value, "c"; actualValue != expectedValue {
+				t.Errorf("Got %v expected %v", actualValue, expectedValue)
+			}
+		default:
+			t.Errorf("Too many")
+		}
+	})
+
+	// Map
+	mappedSet := set.Map(func(index interface{}, value interface{}) interface{} {
+		return "mapped: " + value.(string)
+	}).(*Set)
+	if actualValue, expectedValue := mappedSet.Contains("mapped: a", "mapped: b", "mapped: c"), true; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+	if actualValue, expectedValue := mappedSet.Contains("mapped: a", "mapped: b", "mapped: x"), false; actualValue != expectedValue {
+		t.Errorf("Got %v expected %v", actualValue, expectedValue)
+	}
+	if mappedSet.Size() != 3 {
+		t.Errorf("Got %v expected %v", mappedSet.Size(), 3)
+	}
+
+	// Select
+	selectedSet := set.Select(func(index interface{}, value interface{}) bool {
+		return value.(string) >= "a" && value.(string) <= "b"
+	}).(*Set)
+	if actualValue, expectedValue := selectedSet.Contains("a", "b"), true; actualValue != expectedValue {
+		fmt.Println("A: ", mappedSet.Contains("b"))
+		t.Errorf("Got %v (%v) expected %v (%v)", actualValue, selectedSet.Values(), expectedValue, "[a b]")
+	}
+	if actualValue, expectedValue := selectedSet.Contains("a", "b", "c"), false; actualValue != expectedValue {
+		t.Errorf("Got %v (%v) expected %v (%v)", actualValue, selectedSet.Values(), expectedValue, "[a b]")
+	}
+	if selectedSet.Size() != 2 {
+		t.Errorf("Got %v expected %v", selectedSet.Size(), 3)
+	}
+
+	// Any
+	any := set.Any(func(index interface{}, value interface{}) bool {
+		return value.(string) == "c"
+	})
+	if any != true {
+		t.Errorf("Got %v expected %v", any, true)
+	}
+	any = set.Any(func(index interface{}, value interface{}) bool {
+		return value.(string) == "x"
+	})
+	if any != false {
+		t.Errorf("Got %v expected %v", any, false)
+	}
+
+	// All
+	all := set.All(func(index interface{}, value interface{}) bool {
+		return value.(string) >= "a" && value.(string) <= "c"
+	})
+	if all != true {
+		t.Errorf("Got %v expected %v", all, true)
+	}
+	all = set.All(func(index interface{}, value interface{}) bool {
+		return value.(string) >= "a" && value.(string) <= "b"
+	})
+	if all != false {
+		t.Errorf("Got %v expected %v", all, false)
+	}
+
+	// Find
+	foundIndex, foundValue := set.Find(func(index interface{}, value interface{}) bool {
+		return value.(string) == "c"
+	})
+	if foundValue != "c" || foundIndex != 2 {
+		t.Errorf("Got %v at %v expected %v at %v", foundValue, foundIndex, "c", 2)
+	}
+	foundIndex, foundValue = set.Find(func(index interface{}, value interface{}) bool {
+		return value.(string) == "x"
+	})
+	if foundValue != nil || foundIndex != nil {
+		t.Errorf("Got %v at %v expected %v at %v", foundValue, foundIndex, nil, nil)
+	}
 
 	// Iterator
 	it := set.Iterator()