Refactor VM and operators

internal/object/hash.go

@@ -75,6 +75,46 @@ func (h *Hash) String() string {
 	return h.Inspect()
 }
 
+func (h *Hash) Add(other Object) (Object, error) {
+	if other.Type() != h.Type() {
+		return nil, NewBinaryOpError(h, other, "+")
+	}
+
+	pairs := make(map[HashKey]HashPair)
+	for k, v := range h.Pairs {
+		pairs[k] = v
+	}
+	for k, v := range other.(*Hash).Pairs {
+		pairs[k] = v
+	}
+	return &Hash{Pairs: pairs}, nil
+}
+
+func (h *Hash) Get(index Object) (Object, error) {
+	key, ok := index.(Hashable)
+	if !ok {
+		return nil, fmt.Errorf("invalid hash key %s", index.Type())
+	}
+
+	pair, found := h.Pairs[key.HashKey()]
+	if !found {
+		return &Null{}, nil
+	}
+
+	return pair.Value, nil
+}
+
+func (h *Hash) Set(index, other Object) error {
+	key, ok := index.(Hashable)
+	if !ok {
+		return fmt.Errorf("invalid hash key %s", index.Type())
+	}
+
+	h.Pairs[key.HashKey()] = HashPair{Key: index, Value: other}
+
+	return nil
+}
+
 func (h *Hash) Compare(other Object) int {
 	if obj, ok := other.(*Hash); ok {
 		if len(h.Pairs) != len(obj.Pairs) {