array builtins

object/array.go

@@ -49,3 +49,31 @@ func (ao *Array) Equal(other Object) bool {
 	}
 	return false
 }
+func (ao *Array) Copy() *Array {
+	elements := make([]Object, len(ao.Elements))
+	for i, e := range ao.Elements {
+		elements[i] = e
+	}
+	return &Array{Elements: elements}
+}
+
+func (ao *Array) Reverse() {
+	for i, j := 0, len(ao.Elements)-1; i < j; i, j = i+1, j-1 {
+		ao.Elements[i], ao.Elements[j] = ao.Elements[j], ao.Elements[i]
+	}
+}
+
+func (ao *Array) Len() int {
+	return len(ao.Elements)
+}
+
+func (ao *Array) Swap(i, j int) {
+	ao.Elements[i], ao.Elements[j] = ao.Elements[j], ao.Elements[i]
+}
+
+func (ao *Array) Less(i, j int) bool {
+	if cmp, ok := ao.Elements[i].(Comparable); ok {
+		return cmp.Less(ao.Elements[j])
+	}
+	return false
+}

object/bool.go

@@ -26,3 +26,16 @@ func (b *Boolean) Equal(other Object) bool {
 	}
 	return false
 }
+func (b *Boolean) Int() int64 {
+	if b.Value {
+		return 1
+	}
+	return 0
+}
+
+func (b *Boolean) Less(other Object) bool {
+	if obj, ok := other.(*Boolean); ok {
+		return b.Int() < obj.Int()
+	}
+	return false
+}

object/int.go

@@ -24,3 +24,9 @@ func (i *Integer) Equal(other Object) bool {
 	}
 	return false
 }
+func (i *Integer) Less(other Object) bool {
+	if obj, ok := other.(*Integer); ok {
+		return i.Value < obj.Value
+	}
+	return true
+}

object/null.go

@@ -15,3 +15,6 @@ func (n *Null) Equal(other Object) bool {
 	_, ok := other.(*Null)
 	return ok
 }
+func (n *Null) Less(other Object) bool {
+	return false
+}

object/object.go

@@ -23,6 +23,7 @@ const (
 // Returns `true` iif the types and values are identical, `false` otherwise.
 type Comparable interface {
 	Equal(other Object) bool
+	Less(other Object) bool
 }
 
 // Immutable is the interface for all immutable objects which must implement

object/str.go

@@ -24,3 +24,9 @@ func (s *String) Equal(other Object) bool {
 	}
 	return false
 }
+func (s *String) Less(other Object) bool {
+	if obj, ok := other.(*String); ok {
+		return s.Value < obj.Value
+	}
+	return false
+}