fp-ts VS proposal-pattern-matching

I think it’s great that functional programming is making its way into traditional imperative languages - even JavaScript (I recently came across https://gcanti.github.io/fp-ts/ as a pretty extreme example)

Elixir/Erlang has function-level pattern matching, which I really like. I’ve yet to see it anywhere else, though my understanding is it came from Prolog.

While I certainly agree, I've found that this is often an indication of too-complex an architecture, and a fundamental re-think being necessary. I've had projects that depend on [fp-ts], which end up incredibly generic-heavy, but still make it entirely through a typecheck(not build- typescript's just worse at that than other tools like esbuild) in seconds-at-worse.

Obviously depends on your organization/project/application, but I do like these things as complexity-smells.

[fp-ts]: https://gcanti.github.io/fp-ts/

Unlike more comprehensive functional libraries like fp-ts, each module can be imported and resolved separately. If you just need options, simply add the option module and you're good to go.

While it's quite abstract, I believe it may be useful to those of you who is interested to learn more about functional programming [in Typescript] and also get more intuition on diverse programming ideas. I use fp-ts as a functional programming library there.

The library for TypeScript that this is influenced by is here:

https://github.com/gcanti/fp-ts

Interesting how both languages with this library converge to a similar syntax, due to heavy use of functions.

Learn something that pays the bill first - nowadays it's Golang/Rust react/typescript. Then you can try some pure fp libs like fp-ts and fp-core.rs, and look through existing scala cats docs. If you'll feel bad about it - that's totally fine and expectable, fp takes a paradigm shift and not that many dev able to shift their brains way of thought due to basic psychological rigidity) (inability to change habits and to modify concepts/attitudes once developed). And that's purely a staffing and management issue - folks hired randoms out of the blue, and called 'em a team.

fp-ts, a library that caters to functional programming in TypeScript, comes with some micro-abstractions that already solve a few of our needs.

Also, don't underestimate how powerful TypeScript can be in capable hands (namely Giulio Canti's). Check out fp-ts, for instance.

You are able to type it using function overloads, an example can be found here - link, line 236.

looks like more ergonomic/focused version of fp-ts[1]

[1] https://gcanti.github.io/fp-ts/

Note, however, that there is a proposal to add pattern matching to JS.

There's an ECMAScript proposal that is in the works to add this feature to the language! It's going to look something like this.

More importantly, TypeScript typically commits to build things into itself when the proposal in JavaScript reaches Stage 3. The pattern matching proposal in JavaScript is Stage 1, but depends on many other proposals as well that may or may not need to be at Stage 3 as well for it to work. This particular proposal is interested on pattern matching on JavaScript Objects and other primitives, just like Python does with it’s native primitives. These are also dynamic types which helps in some areas, but makes it harder than others. Additionally, the JavaScript type annotations proposal needs to possibly account for this. So it’s going to be awhile. Like many years.

For true™ functional programming in JS, native pattern matching and partial function application are missing (at least for now: 1, 2). For proper OOP, it lacks real interfaces and compile-time dependency injection.

The proposal for pattern matching syntax seems more akin to what they're looking for.

https://github.com/tc39/proposal-pattern-matching

There's a proposal to add something like that to JavaScript but it's been stuck in limbo since 2017 although there are libraries like ts-pattern which implement it already.

I'll admit, it is easy to assert that the TypeScript language should not be involved in the matters of packages but I also wonder if we're moving towards a point where interfaces will be as common as namespaces and whether or not it would be sensible for the language to incorporate such type assertions into the language formally, after all, it already compiles to various forms of JavaScript and there is a stage 1 proposal submitted to the TC39 committee to give JavaScript pattern matching. If adopted, wouldn't it make sense to allow TypeScript to compile a type into a type guard for the native JavaScript pattern matcher?

Both are active tc39 proposals :)

https://github.com/tc39/proposal-pipeline-operator - Stage 2

https://github.com/tc39/proposal-pattern-matching - Stage 1

Hopefully we get both in the next couple of years.

We often add promising TC39 proposals into Civet so people can experiment without waiting.

We've added https://github.com/tc39/proposal-pipeline-operator, a variant of https://github.com/tc39/proposal-pattern-matching, a variant of https://github.com/tc39/proposal-string-dedent and others.

Since our goal is to be 99% compatible with ES we'll need to accommodate any proposals that become standard and pick up anything TC39 leaves on the table (rest parameters in any position, etc.)