You can write 'type signatures' easily in clojure code, there's dozens of options, they're just only checked at runtime (and usually relegated to developer builds). if you combine that with good code coverage, it stops being a weakness and starts being a strength, because you declare data types with far more specificity & precision than a static type system.

As rich likes to say, the type signature of your stereotypical statically typed language, e.g. reverse :: [a] -> [a], doesn't have a much information content.

I write clojure, and still 'think in types' & category theory.