release 0.4.0

Author: Tomasz Gałkowski

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.0] - 2020-09-26
+
 ### Added
 - adds lens function
 
@@ -96,7 +98,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - reverse function
 - tail function
 
-[Unreleased]: https://github.com/galkowskit/denofun/compare/0.3.0...HEAD
+[Unreleased]: https://github.com/galkowskit/denofun/compare/0.4.0...HEAD
+[0.4.0]: https://github.com/galkowskit/denofun/compare/0.3.0...0.4.0
 [0.3.0]: https://github.com/galkowskit/denofun/compare/v0.2.0...0.3.0
 [v0.2.0]: https://github.com/galkowskit/denofun/compare/v0.1.0...v0.2.0
 [v0.1.0]: https://github.com/galkowskit/denofun/releases/tag/v0.1.0