import { Equal, Expect } from '../helpers/type-utils';
import { F } from 'ts-toolbelt';
interface Fruit {
name: string;
price: number;
}
export const wrapFruit = <TFruits extends Fruit[]>(
fruits: F.Narrow<TFruits>
) => {
const getFruit = <
TName extends TFruits[number]['name']
>(
name: TName
): RT => {
return fruits.find((fruit) => fruit.name === name) as Extract<TFruits[number], { name: TName }>;
};
return {
getFruit,
};
};
const fruits = wrapFruit([
{
name: 'apple',
price: 1,
},
{
name: 'banana',
price: 2,
},
]);
const banana = fruits.getFruit('banana');
const apple = fruits.getFruit('apple');
// @ts-expect-error
const notAllowed = fruits.getFruit('not-allowed');
type tests = [
Expect<Equal<typeof apple, { name: 'apple'; price: 1 }>>,
Expect<Equal<typeof banana, { name: 'banana'; price: 2 }>>
];
See how to extract the RT: RT extends Extract<TFruits[number], { name: TName }>