frunk

I don't understand why you call it "trickery or "fake". Church encoding of natural numbers is the same technique used in Agda, Coq and Idris to represent the Peano numbers. It's a completely valid encoding and isomorphic to any other representation. You don't need to use a fixed-length array either - you can used a recursive linked list at the type-level for an unbounded encoding [1]. The Scala library is an example of that; the Github page even has an example of encoding arbitrary units like sheep and wheat. [1] https://github.com/lloydmeta/frunk

It's especially relevant in PL or Databases. DB2 did such foundational work in database theory, and Python 3.6's new dicts finally made some very simple database theory finally available to users. In PL, there's a massive amount of awesome languages that pretty much existed for the purpose of writing a PhD or doing something funky with semantics. It takes /really really/ long to get into an industrial strength language. Look at Rust for example, it's the first incidence of real Algebraic types for a non-gc language (excluding C++), letting you do wonderful things like https://github.com/lloydmeta/frunk Some of my favorites are http://bloom-lang.net/ https://www.luna-lang.org/ https://www.propellerheads.com/en/reason (i contend it's a fantastic programming language for the task) https://cseweb.ucsd.edu/~wgg/CSE131B/oberon2.htm