https://github.com/imjuni/my-only-either
https://github.com/imjuni/my-only-either
Last synced: 11 months ago
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- Host: GitHub
- URL: https://github.com/imjuni/my-only-either
- Owner: imjuni
- License: mit
- Created: 2022-05-03T16:10:17.000Z (about 4 years ago)
- Default Branch: main
- Last Pushed: 2022-08-30T17:28:11.000Z (almost 4 years ago)
- Last Synced: 2024-10-20T14:55:55.389Z (over 1 year ago)
- Language: TypeScript
- Size: 422 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# my-only-either
[](https://npmcharts.com/compare/my-only-either?minimal=true) [](https://github.com/imjuni/my-only-either) [](https://github.com/imjuni/my-only-either/issues) [](https://www.npmjs.com/package/my-only-either) [](https://github.com/imjuni/my-only-either/blob/master/LICENSE)
Simple Type and Function set for Either interface. Either important concept in functional programming. But Node.js and TypeScript don't have implmentation. So you can choose another functional implementation like [fp-ts](https://github.com/gcanti/fp-ts) or anther functional utility. But if you need only Eihter, this package is good alternative.
# Why? use Either?
## Zero Dependency
my-only-either not use package. only 1k(1,489byte) size.
## Help functional programming
Helpful for functional programming and integrate return type. See below.
```ts
import { parse as jsoncParse } from 'jsonc-parser';
import { parse as json5Parse } from 'json5';
function json5Parse(value: string): PassFailEither> {
try {
return pass(json5Parse(value));
} catch (err) {
return fail(new Error(err));
}
}
function jsoncParse(value: string): PassFailEither> {
try {
return pass(jsoncParse(value));
} catch (err) {
return fail(new Error(err));
}
}
function parse(value: string): Record {
const jsoncParsedEither = jsoncParse(value);
if (isPass(jsoncParsedEither)) {
return jsoncParsedEither.pass;
}
const json5ParsedEither = json5Parse(value);
if (isPass(json5ParsedEither)) {
return json5ParsedEither.pass;
}
throw new Error(json5ParsedEither.fail);
}
```
throw keyword move control-flow. But Either, PassFailEither don't move control-flow besides Either helpful functional programming and function pipe.
# Either
Name using left and right.
| name | category | description |
| :- | :-: | :- |
| ILeft | type | Left interface |
| IRight | type | Right interface |
| Either | type | Either type using ILeft and IRight |
| TPickLeft | utility type | Return Type of left in Either |
| TPickILeft | utility type | Return Type of ILeft in Either |
| TPickRight | utility type | Return Type of right in Either |
| TPickIRight | utility type | Return Type of IRight in Either |
| left | function | value convert ILeft type |
| right | function | value convert IRight type |
| isLeft | function | check given value is ILeft type |
| isRight | function | check given value is IRight type |
# PassFailEither
Name using pass and fail.
| name | category | description |
| :-: | :-: | :- |
| IFail | type | Fail interface |
| IPass | type | Pass interface |
| PassFailEither | type | PassFailEither type using IFail and IPass |
| TPickFail | utility type | Return Type of fail in Either |
| TPickIFail | utility type | Return Type of IFail in Either |
| TPickPass | utility type | Return Type of pass in Either |
| TPickIPass | utility type | Return Type of IPass in Either |
| fail | function | value convert IFail type |
| pass | function | value convert IPass type |
| efail | function | value convert IFail type, exactly same fail. If you use jest or test runner this function is helpful for auto import & auto complete |
| epass | function | value convert IPass type, exactly same pass. If you use jest or test runner this function is helpful for auto import & auto complete |
| isFail | function | check given value is IFail type |
| isPass | function | check given value is IPass type |
# Type order in Eiter, PassFailEither
First type arguments is ILeft or IFail. Because fp-ts and many functional programming language choose first type is left(or fail).
```ts
type Either = ILeft | IRight;
```