Methods for option

[Sstark97]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Description

In this PR I have added two methods for the Option cutie:

• ofSome: Creates an Option with a safe value, so it will return the subtype Some
• ofNone: Creates an Option with no value, so it will return the subtype None

const some = Option.ofSome(5);
some.match(console.log, () => console.log('none')); // 5

const none = Option.ofNone();
none.match(console.log, () => console.log('none')); // none

Added/updated tests?

• Yes
• No, and this is why: please replace this line with details on why tests
  have not been included
• I need help with writing tests

What gif best describes this PR or how it makes you feel?

[Sstark97]

I don't know how the ofSome method should behave with null/undefined, what do you think the behavior should be?

const nullishSome = Option.ofSome(null) // ???
const undefinedSome = Option.ofSome(undefined) // ???

[Marius9595]

I don't know how the ofSome method should behave with null/undefined, what do you think the behavior should be?

const nullishSome = Option.ofSome(null) // ???
const undefinedSome = Option.ofSome(undefined) // ???

mmm maybe we could create this Type:

type NotNullable<T> = T extends null | undefined ? never : T

So, ofSome method should be something like:

  static ofSome<T>(value: NotNullable<T>): Some<T> {
    return new Some(value);
  }

In this way, the TS compiler raises an error if you try to pass an undefined or null as value with the static analysis

[Sstark97]

Y try to do this, but not working well, not raise a compiler error. In the editor I see a warning, but the test pass:

I tried two options for NotNullable type:

//type NotNullable<T> = T extends null | undefined ? never : T
export type NotNullable<T> = Exclude<T, null | undefined>;

And I add this in tsconfig:

{
  "compilerOptions": {
    "strict": true,
    "strictNullChecks": true,
  },

You can check all details in the last commit

[Marius9595]

From my point of view, this cannot be tested with Vitest or Jest with a test case. I mean, the test actually is the static analysis of code, if this finds an error it will notify the developer to fix it (as a red test case). In addition, You can try to run a build, this should fail. At the end, we can pass anything in runtime a function that allows statically a specific type as input parameter 😟

Could you verify my guess, running the build action?

[Sstark97]

Yeah this worked well! 😄

In the next commit the code will be ready

[myugen]

I really like to see more people involved in the library.

I really appreciate your contribution @Sstark97 ❤️

[Marius9595]

Same, thanks for this contribution @Sstark97! ❤️

[myugen]

@Sstark97 if you consider PR is ready, you can remove Draft state.

[Marius9595]

Nice job @Sstark97!

I put some comments to solve some doubts on my side

The merge-base changed after approval.

Solved