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  • License MIT

Rust like enums for Typescript

Package Exports

  • iron-enum
  • iron-enum/dist/mod.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (iron-enum) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

Iron Enum

Finally Rust like enums in Typescript!

  • Ergonomic AF!
  • Fully type safe!
  • Only 500 bytes!

Typescript enums only provide simple variants:

enum Shape {
    Square,
    Circle
}

But what if you wanted to provide data for each variant that is context specific? Well now you can!

import { IronEnum } from "iron-enum";

const ShapeEnum = IronEnum<{
    Empty: {},
    Square: { width: number, height: number },
    Circle: { radius: number }
}>();

const exampleShape = ShapeEnum.Square({width: 22, height: 50});

// Supports matching
exampleShape.match({
    Empty: () => {
        // runs if the shape is empty
    },
    Square: ({width, height}) => {
        // runs if the shape is square
    },
    Circle: ({radius}) => {
        // runs if the shape is circle
    }
});

// Supports fallback cases and returns through match
const result = exampleShape.match({
    Square: ({width, height}) => {
        // runs if the shape is square
        return width;
    },
    _: () => {
        // runs if it's anything but a square
        return "hello"
    }
});
// result type is inherited from match arm return types.
// typeof result == number | string

if (exampleShape.if.Square()) {
    // runs if the shape is a square
}

if (exampleShape.ifNot.Square()) {
    // runs if the shape is NOT a square
}

console.log(exampleShape.unwarp())
// output: ["Square", { width: 22, height: 50 }]

// this method will only allow ShapeEnum variants as an argument
const someFn = (onlyShapeEnum: typeof ShapeEnum._self.prototype) => {

}

Just like in Rust, the .match(...) keys must contain a callback for each variant OR provide a fallback method with a _ property. Failing this constraint leads to a type error.