# [TypeScript]’s Type System, 62 bytes

```lang-typescript
type U<N,L extends 1[]=[]>=L extends{length:N}?L:U<N,[...L,1]>
```

[Try it at the TypeScript Playground!](https://tsplay.dev/wE8Q2W)

Type definition taking a generic integer type and recursively appending 1 to a tuple type until its length is the integer type.

[TypeScript]: https://www.typescriptlang.org