microsoft / microsoft/TypeScript
Allow tuple labels passed to `satisfies` to participate in type inference
Ninguém assumiu esta issue ainda.
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Descrição
### 🔍 Search Terms
tuple, tuples, label, labels, tuple labels, satisfies, as const
### ✅ Viability Checklist
- [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code
- [x] This wouldn't change the runtime behavior of existing JavaScript code
- [x] This could be implemented without emitting different JS based on the types of the expressions
- [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- [x] This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- [x] This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals
### ⭐ Suggestion
Hey TypeScript team! First of all, _super_ excited to hear about `tsgo`.
I've got a feature request for y'all -- the body of this issue was ported from a playground that I created:
https://tsplay.dev/NljeQW
Basically, I often find myself using the `satisfies` operator to define mutable tuples inline:
```typescript
const base = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] as const satisfies any[]
// ^? const base: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
```
Sometimes when working with tuples of a known length, I use labels, because why not? Free semantics!
But to get the behavior I'm after, I have to add a layer of indirection.
```typescript
const ex = [0, 0] as const
type Example = never | [x: typeof ex[0], y: typeof ex[1]]
const example: Example = [...ex]
// ^? const example: [x: 0, y: 0]
```
This makes the code more confusing to read, which makes the tradeoff basically a wash.
### __Feature Request__
Allow any labels passed to `satisfies` to participate in type inference, like so:
```typescript
const point = [0, 0] as const satisfies [x: any, y: any]
//
// Desired type:
// ^? const point: [x: 0, y: 0]
// ^ ^
```
Let me know if you'd like a more complex example, or if there's anything else I can provide.
### 📃 Motivating Example
Playground:
https://tsplay.dev/NljeQW
### 💻 Use Cases
1. What do you want to use this for?
Adding free semantics
3. What shortcomings exist with current approaches?
Requires a layer of indirection + introduces the possibility of drift
5. What workarounds are you using in the meantime?
Outlined in the example I shared
Guia de contribuição
Primeiros passos
- Leia a issue inteira e depois o guia de contribuição do projeto.
- Comente na issue dizendo que vai assumir — evita que duas pessoas façam o mesmo trabalho.
- Faça um fork do repositório e trabalhe em uma branch.
- Abra um pull request que referencie o número da issue.
Direção de pesquisa
Comece pelo TypeScript Playground vinculado e reproduza os exemplos envolvendo satisfies, as const e labeled tuples. A issue não nomeia arquivos-fonte nem testes; a conclusão significa que os labels fornecidos por meio de satisfies participem da inferência, preservando os tipos demonstrados dos elementos da tupla.
Escrita pelo modelo de indexação a partir do texto da issue.
Avaliação
- Stack de tecnologia
- typescript
- Domínio
- compilers
- Tipo de issue
- Funcionalidade
- Dificuldade
- 5/5
- Tempo estimado
- Mais de uma semana
- Status de atividade
- Estagnada
- Clareza
- Razoavelmente clara
- Facilidade para iniciantes
- 38/100