TypeScriptでNonEmptyな配列型 - 要素が必ずある配列 - nwtgck / Ryo Ota

TypeScriptでNonEmptyな配列型 - 要素が必ずある配列

code:ts

type NonEmpty<T> = [T, ...T[]];

const a1: NonEmpty<number> = 1, 2, 3;

const a2: NonEmpty<number> = 1;

const a3: NonEmpty<number> = []; // compile error GOOD!

https://www.typescriptlang.org/play/#src=type%20NonEmpty<T>%20%3D%20%5BT%2C%20...T%5B%5D%5D%3B%0A%0Aconst%20a1%3A%20NonEmpty<number>%20%3D%20%5B1%2C%202%2C%203%5D%3B%0Aconst%20a2%3A%20NonEmpty<number>%20%3D%20%5B1%5D%3B%0Aconst%20a3%3A%20NonEmpty<number>%20%3D%20%5B%5D%3B%20%2F%2F%20compile%20error%20GOOD!%0A

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