> If the only thing you inject is data, can we still call that "dependency injection"?

I suppose that's a philosophical question.

Probably the 2 most common functions I 'dependency inject' are rand() and time.now(). I feel like they count, but you might not.

I mean, if you pass a HOF to some other function, then that is also a dependency.

Correct, but I haven't seen it happen often in practice. I mean, pretty much every project uses HOF, but few have many of them.

I also tend to avoid HOF when I can instead pass data around explicitly.

You're one sentence away from discovering Common Lisp ; )

Define data.

Anything that doesn't have an arrow in its type.