Comment by crabbone

Every language is both statically and dynamically typed. But the more correct way of saying this is "dynamically or statically checked". Types don't appear or disappear when a program runs. The difference is in what can be known about types and at what stage.

What programmers actually care about is this:

How can we check more and sooner in a way that requires less mental energy on the side of the programmer to write?

In other words, we have three variables we want to optimize for: how much is checked, how much is checked before execution, how much effort does it take to write the check. When people argue for "statically or dynamically typed languages", they generally don't understand what they argue for (or against), as they don't have this kind of mental model in mind (they just learned the terms w/o clear understanding of what they mean).

And so do you.

So, I don't really know what do you mean when you say "dynamically typed". Which language is that? Are you talking about Erlang? SML? What aspect of the language are you trying to describe?

NB. I don't think either C# or Java have good type systems. My particular problem with these is subtyping, which is also a problem in OCaml and derivatives s.a. Scala or F#. It's not a solution anyone wanted, it's a kludge that was added into these systems to deal with classes and objects. So, if we are going after good type systems... well, it wouldn't be in any language with objects, that's for sure.

NB2. Unix Shell has a great type system. Everything is a string. It's a pleasure to work with, and you don't even need a type checker! For its domain, it seems like a perfect compromise between the three optimization objectives.