[eyelidlessness]

> Could you provide a concrete example?

I wish I could, it's been years since I've actually written or even read any ClojureScript. But I can offer something more general. Many core functions expecting a collection type would blow up deep in the call stack, usually in helper functions not exposed or documented in the core API, when passed a value which provides no iteration. I would encounter these scenarios frequently when recursing over a nested structure (e.g. oops I passed a keyword or a function to `map`), or when I simply got argument order wrong.

Like I said, this eventually drove me to static typing, and I wouldn't ever consider a language without it again. Most dynamic languages have too large a core interface to commit it to memory, and even "small" languages reproduce that in the libraries we build.