If you have the time and the interest, start with Standard ML. It is one of (or just?) the simplest languages in the ML family (which also include OCaml, Haskell, Scala, etc.).
You'll see yourself wanting a number of features you'd expect in a modern language, and end up discovering the motivation and approach behind how Scala or Haskell work. Operator overloading (ad-hoc polymorphism) and modular implicits are two of the ones I come across the most.
I have always felt that Haskell and Scala (and OCaml sorta) are way too complicated. However, spending time learning Standard ML and the foundations of this family have been really illuminating - you'll discover how powerful Haskell and Scala really are. For an analogy, you can think of switching to FreeBSD from Linux to get closer to Unix roots so you can understand Linux (the historic decisions and reasons) better.
Take a look at the /r/sml wiki [0] if you need help getting started.
You'll see yourself wanting a number of features you'd expect in a modern language, and end up discovering the motivation and approach behind how Scala or Haskell work. Operator overloading (ad-hoc polymorphism) and modular implicits are two of the ones I come across the most.
I have always felt that Haskell and Scala (and OCaml sorta) are way too complicated. However, spending time learning Standard ML and the foundations of this family have been really illuminating - you'll discover how powerful Haskell and Scala really are. For an analogy, you can think of switching to FreeBSD from Linux to get closer to Unix roots so you can understand Linux (the historic decisions and reasons) better.
Take a look at the /r/sml wiki [0] if you need help getting started.
[0] https://www.reddit.com/r/sml/wiki