Add P.object and P.object.empty #233

gitsunmin · 2024-03-23T15:31:12Z

Add P.object and P.object.empty

Add a pattern to match all 'Object' and 'Empty Object'.

`P.object`

const fn = (input: object) =>
  match(input)
    .with(P.object, () => 'Object!')
    .otherwise(() => '???');

console.log(fn({ str: 'hello' })); // Object!

`P.object.empty`

const fn = (input: string) =>
  match(input)
    .with(P.object.empty(), () => 'Empty!')
    .otherwise(() => 'Full!');

console.log(fn({})); // Empty!

Issue number: #230

gvergnaud

Thank you for contributing! I have a few comments but that's a good start :)

gvergnaud · 2024-03-27T12:51:26Z

src/patterns.ts

+  pattern: pattern
+): ObjectChainable<pattern> =>
+  Object.assign(chainable(pattern), {
+    empty: () => objectChainable(intersection(pattern, emptyObject())),


Seems like chainable would be enough here, since you can't chain empty several times

Yes, I'll change it to "chainable." If it's wrong, please "comment."

src/patterns.ts

gvergnaud · 2024-03-27T12:55:14Z

src/types/Pattern.ts

  | 'or'
  | 'and'
  | 'array'
+  | 'object'


I'm not sure a new pattern type is necessary here because both patterns you added are implemented with guards

I'll erase "object".

gvergnaud · 2024-03-27T12:56:09Z

src/types/Pattern.ts

  GuardP<unknown, null | undefined>,
  never
 >;
-


Could you remove this diff?

yes, I'll remove this diff

gvergnaud · 2024-03-27T12:56:51Z

src/types/Pattern.ts

+       * match(value)
+       *  .with(P.object.empty(), () => 'empty object')
+       */
+      empty<input>(): ObjectChainable<


It should just be Chainable here as well

gvergnaud · 2024-03-27T13:01:55Z

tests/object.test.ts

+        type t = Expect<Equal<typeof obj, { str: 'world' }>>;
+        return obj.str;
+      })
+      .with(P.object, (obj) => {


Could you add test covering how P.object behaves with more inputs:

Functions

Primitive values

Null

It should catch all values that are assignable to the object type, and type narrowing and exhaustive should both work

I've added test. If you need more, please comment

Actually, functions and arrays are part of the object type in TypeScript: Playground

I think P.object should catch anything assignable to object to stay close to typescript semantics and play nicely with exhaustiveness checking.

I'm going to update your PR shortly

- Comment: Seems like chainable would be enough here, since you can't chain empty several times - Comment: I think we could make this more efficient by using a for in loop instead of Object.keys and breaking the loop by returning false if an object own property is encountered. - Comment: It should just be Chainable here as well - Comment: I'm not sure a new pattern type is necessary here because both patterns you added are implemented with guards - Comment: Could you add test covering how P.object behaves with more inputs: Functions, Primitive values, Null. It should catch all values that are assignable to the object type, and type narrowing and exhaustive should both work - Comment: Could you remove this diff?

gvergnaud · 2024-03-31T20:14:52Z

I wanted to make a few changes and realized I can't push to your repository so I had to create a new branch that includes your changes. Closing this PR in favor of #234

gitsunmin added 2 commits March 24, 2024 00:01

docs: add P.object on README.md

27f8749

Add object, object.empty pattern and tests

ea7a937

gitsunmin changed the title ~~Add P.object and P.object.empty #230~~ Add P.object and P.object.empty Mar 23, 2024

gvergnaud reviewed Mar 27, 2024

View reviewed changes

gitsunmin force-pushed the main branch from 396687b to 1831e29 Compare March 28, 2024 15:42

Fix objectChainable type in patterns.ts and Pattern.ts

f17c02c

gvergnaud closed this Mar 31, 2024

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Add P.object and P.object.empty #233

Add P.object and P.object.empty #233

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