[eigenhombre]

Not the OP but:

One can develop with TDD in Clojure quite smoothly depending on choice of tooling; with CIDER in Emacs there are keyboard shortcuts to run tests for the current namespace or the entire project, so feedback can be very fast (if your tests are fast). I've also used (some time ago) test runners that stay running and re-test when a file is saved.

In fact, it can be nice to do one's explorations in the REPL and then reify one's discoveries as tests.

Regarding types: I will say that working on larger Clojure (and Python) projects with somewhat junior teams made me more curious about type systems. Clojure's immutable collections and the core abstractions they are built around are great, but it can take some skill and discipline to keep track of exactly what kind of data is flowing through any particular part of your program. But, there is some support for à la carte strictness in the language via Spec, Malli, structured types, etc.

[hhhAndrew]

> In fact, it can be nice to do one's explorations in the REPL and then reify one's discoveries as tests.

This is how I wrote unit tests when I worked on Mathematica: try out every edge cases of the function in a notebook, and then use a tool to extract all the input/output cells and convert them to tests. I didn't know the term reify for this practice, I like it!

[erichocean]

Reify is a general term, it means to "make concrete" (or to "make real" depending on the usage) something that is previously fuzzy or abstract.

When you make a concrete subclass of an abstract class, you are "reifying" that class. When you made the abstract class from the concept of something, you are "reifying" that concept.

It's a fun word.