Allow customization of type display format in hover tooltips

まず、ホバーツールチップの型がどのようにフォーマットされているか、また AST の WriteArrayAsGenericType フラグがどこで使われているかを追跡します。compilerOptions がどのように定義され、使用されているかを確認し、そのうえでジェネリック配列型と短縮配列型に必要な設定および表示動作を判断します。選択した形式が、出力される JavaScript を変更せずにホバーツールチップに一貫して表示されれば完了です。

🔍 Search Terms

• customization type display
• Array or T[]

✅ Viability Checklist

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

In TypeScript, when hovering over a variable, the inferred type is displayed in a specific format.
For instance, an array of numbers is shown as number[].
However, some developers, including myself, prefer the alternative format Array<number> for readability and consistency with other generic types.

📃 Motivating Example

I have noticed that there is an WriteArrayAsGenericType flag in the Abstract Syntax Tree (AST) that can convert T[] to Array<T>.

I would like to request the addition of a configuration option in tsconfig.json to enable this flag, allowing developers to choose their preferred format for array types in hover tooltips.

For example:

{
  "compilerOptions": {
    "typeDisplayFormat": "generic" // Options could be "generic" for Array<number> or "shorthand" for number[]
  }
}

💻 Use Cases

Complex Type Readability: I frequently write functional code that can lead to complex types like Task<Maybe<Task<Maybe<T[]>>[]>>[]. The shorthand [] notation can make it difficult to understand the nested generic relationships. Displaying these types as Array<T> would significantly improve readability and comprehension.

Consistency: Most other generic types use angle brackets (e.g., Promise<T>, Map<K, V>), and only array types use the special shorthand (number[]). Aligning array types with this convention would ensure consistency across all types and improve clarity.