refactor: rename lancetconstraints package name to constraints

constraints/constraints.go

@@ -0,0 +1,13 @@
+// Copyright 2021 dudaodong@gmail.com. All rights reserved.
+// Use of this source code is governed by MIT license
+
+// Package constraints contain some custom interface.
+package constraints
+
+// Comparator is for comparing two values
+type Comparator interface {
+	// Compare v1 and v2
+	// Ascending order: should return 1 -> v1 > v2, 0 -> v1 = v2, -1 -> v1 < v2
+	// Descending order: should return 1 -> v1 < v2, 0 -> v1 = v2, -1 -> v1 > v2
+	Compare(v1, v2 any) int
+}