int32 type returned by bitwise operators

Search Terms

bitwise operators, integer type, int32

Suggestion

Add an int32 subtype for number returned by TypeScript from bitwise operators.

function coerce(n: number): int32 {
  return n | 0;
}

JavaScript bitwise operators coerce arguments to int32 and the return type of those operators will always be an int32.

This would not be a breaking change since int32 would be a subtype of number. Only bitwise operations would change to return int32s.

EDIT: I now recommend calling the type BitwiseInt32 so that user’s won’t see the type as a generic integer type.

Use Cases

Helps applications which are trying to take advantage of JavaScript implementations int32 optimizations. An application could ask for an int32 parameter to force coercion with n | 0.

Checklist

My suggestion meets these guidelines:

• 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, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

まず、提案されている int32/BitwiseInt32 の動作と、リンクされているビット演算子に関する ECMAScript 仕様を読んでください。TypeScript がビット演算子の戻り値の型をどのように表現しているかを追跡し、coerce の例を確認してください。ビット演算子が提案されたサブタイプを公開しつつ number に代入可能なままであり、設計と命名が解決されていれば完了です。