test VS Elm

The de-facto standard for testing an Elm application is elm-test. However, as noted in the README:

Once all that handwritten C code was solid, I needed to make sure the C generated from Elm was working properly. I found the source for the core library's unit tests and decided to port them into my project and add some of my own tests. You can run the tests in WebAssembly in your browser too. (Funnily enough, one of the biggest challenges was getting the Elm Test framework itself to run! The framework is more complex than the tests themselves. I still need to come back to the fuzzer tests!)

Lesson Learned: Elm has built in recursion improvements for a variety of positive reasons, and you should think in recursion to solve looping problems. Use property/fuzz tests and bounds checking with early exit to prevent this from locking up your UI (i.e if > 9000, omg abort). If you’re algorithm is reasonable, but the data set is just gigantic, offload to a server instead for more horsepower. Or Workers if you don’t have server chops, can’t upload the large data, or don’t trust your server devs. (“But Doc, I’m the server dev!” Good joke. Ever̸y̴b̸ody laugh. Roll on s̵͓̆nâ̶̱re drum. Curtains.)

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/