I have used PowerShell, and currently learning Clojure. They never occurred to me as being similar - or did I miss the point?

Is a very subtle one.

Imagine having a workstation where the whole stack is written in Clojure (e.g. Lisp Machine).

Now when you open a REPL window, similar to what Common Lisp Interface Manager is, you can (:require) anything public from the OS, including applications, to interact with.

Powershell is similar in that, you are using objects and are able to reference any .NET class, COM instance or public functions from native DLLs by importing them.

So you can for example, import the Office COM automation API and interact with an Excel document that you just selected from the shell.

Office COM automation is what I did. I get what you mean, but in my experience, interfacing with native code is not always straightforward. Also there are odd cornercases where you need to fallback to p/invoke.

But More importantly, you can't change anything, you can only use it. So the FFI is nice and easy, but you could say the same about other languages. Or am I confusing things with Smalltalk images? Cl was somewhat before my time.