Web developer wants to learn statically typed language

I would recommend elm for a hobbyist and as a first exposure to functional programming that is a lot of fun. Your code will only run on browsers (as of now).

Scala is better for heavy duty work, and works on backend, frontend, simple android apps if you must, data science applications. It gives a lot more power and requires more effort to master.

I recommend http://elm-lang.org which is statically typed and designed for web development.

Scala