Discussion on "Functional TypeScript in Production Systems"

Anthony Manning-Franklin · 2021-05-09T09:23:17.771Z

Functional programming has enjoyed a massive surge in popularity amongst JavaScript developers in recent years. This is likely partly due to the popularity of libraries like Redux and React which promote functional programming styles, and have proven...

Omg, this is the blog I was searching for a long time. I was trying to do OOP in TypeScript and sometimes I felt like I didn't harness the power of FP. And great job in that Partially Applied Controller that encapsulate impure + pure function and separate function logic into 3 parts:

Data Retrieval (In-memory, File, DB, Remote API, ...)
Business Logic
Error/Exception Handler for both Data Retrieval and Business Logic (using Discriminated Union Type or Either Design Pattern). I'm currently learning Either Design Pattern.

These knowledge will definitely be put in use in my VSCode Extension that used TypeScript. This is also the project for my graduation thesis.

Great Article!

By the way, I had this question in my mind:

Is using enum in switch ... case a good idea?

This is also bugging my mind since using enum means you don't need to remember the exact literal string like "PENDING_VERIFICATION". You just define

enum AccountStatus {
  PendingVerification = 'PENDING_VERIFICATION';
  Active = 'ACTIVE',
  Locked = 'LOCKED'
}

and use VSCode autocomplete feature. E.g. AccountStatus.Pend- => AccountStatus.PendingVerification

VH VSCode will still autocomplete a union of string literals for you, e.g.

type Foobar = 'FOO' | 'BAR';

const doFoobar = (prop: Foobar) => prop;

When you use doFoobar VSCode will suggest/autocomplete once you have typed doFoobar(

Anthony Manning-Franklin Yep it sure supported autocomplete, my bad @@ and I also found out about how enum wasn't that good in TypeScript so I have fully switched to Union Type now.

Ah yes thank you for these awesome blog plots. I have implemented some in my project. I also ask questions in some of your article's comment section. Can you please check them :")

Great article! Love the examples you use Anthony Manning-Franklin

Geeking out with this piece. How long did it take to implement these functions?

Thanks for the question!

I think I wrote this entire article in a couple of hours, plus some proof reading from my partner, writing the code maybe took up 25% of that time?

These functions are basically muscle memory for me now. By repeating the pattern over and over, I don't need to burn brain cycles remembering the pattern, I only need to think about the particular requirements of the business case being implemented.

This is the value of the practice of Kaizen. Have some exercises you repeat regularly, so you can internalise common patterns. Each time you do it, you will also make little improvements.

Then when it comes time to do it for real, you're not practicing in production on company time.

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Functional TypeScript in Production Systems

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