For dynamically typed languages, using a popular type annotation syntax (e.g. rdoc for ruby, closure compiler for javascript) and an IDE (like Intellij) can giv

For dynamically typed languages, using a popular type annotation syntax (e.g. rdoc for ruby, closure compiler for javascript) and an IDE (like Intellij) can give you 80% of the benefits of type safety by doing code inspection on-the-fly and warning you when it finds incorrect types. The main downside is no compiler safety net when you try to refactor code.