Open-sourcing Sorbet: a fast, powerful type checker for Ruby
It's been funny to watch how more and more static type systems are getting bolted on to dynamically typed languages in recent years.<p>Typescript (with stellar adoption), native type annotation support in Python, Sorbet, PHP 7, Elixir + Dialyzer, ...<p>I wonder why there isn't a popular gradually typed language that natively allows writing both dynamic and type-safe code, allowing quick prototyping and then gradual refactor to type safety.<p>I guess in part because it's a big challenge to come up with a coherent type system that allows this, the bifurcation in the ecosystem, and often a somewhat leaky abstraction. Eg in Typescript you will often still run into bugs caused by malformed JSON that doesn't fit the type declaration, badly or insufficiently typed third party libraries, ....<p>Google's Dart is the only recent, somewhat popular language (only due to Flutter) that allows this natively - that I can think of right now.<p>I do think such a language would be very beneficial for the current landscape though, and projects like this show there is a clear need.<p>Edit: just remembered another option: Crystal. Also Julia, as pointed out below.