pure-raft VS Elm

I have had excellent success with this approach when implementing the Raft algorithm. Raft involves a complex state machine that uses several notionally "asynchronous" operations (sending/receiving messages, storing/loading data from disk, triggering events on timeouts). But that doesn't mean that it needs to be async. For example, instead of having the user of the crate implement a "Storage" trait with asychronous methods, it simply returns a list of the storage operations that must be executed. The caller is free to execute these however they want, sync or async. Traits are a convenient tool for polymorphism, but are not the only one, and will frequently lead to ugly/complex architectures when combined with async.

Elm [1] is based on a similar idea. Build your app from pure functions that return HTML tags.

[1] https://elm-lang.org/

You also wouldn't really be creating your own new programing language. You would be creating something that can run JavaScript by following JavaScript standards and syntax. You might be able to add some non-standard features of your own on top of those standards, or include your own standard library of helpers or utilities, but you can't completely make a new or alternative language and then load it in the browser (or at least not by reimplementing ECMAScript standards... you actually can make your own language that runs within any Javascript enviroment, if you provide an interpreter or compiler that transforms it into valid JS. Some people have done something like this, eg Elm: https://elm-lang.org/).

You should at least have a look at https://elm-lang.org/ it is a pure functional language like Haskell (although with fewer fancy syntax/type classes) but it has some lovely libraries for visualisation and even with plain elm (+ elm-ui) doing string transformations can be easily done.

I get it. However, the whole point of using Unions to narrow your types, ensure only a set of possible scenarios can occur, and only access data of a particular union when it’s safe to do so. That’s some of what pattern matching can provide, and 100% of what using switch statements in TypeScript with their Discriminated Unions can provide. Yes, it’s not 100% exhaustive, but TypeScript is not soundly typed, and even Elm which is still has the same issue TypeScript does: You’re running in JavaScript where anything is possible. So it’s good enough to build with and much better than what you had.

The beauty of a language like Elm (and other lambda-calculus / functional programming inspired languages) is that there's very little transformation involved in going from an idea to code. And that seems to have a big impact on getting things done.

I think the most fun and approachable way for beginners to build games with functional programming is with Elm [1].

See a few (small, demo) games built by the community in [2] .

Notice Elm has abandoned the FRP approach in favor of Model-View-Update [3].

[1] https://elm-lang.org/