Type Alias CountTrue<T, Acc>

CountTrue: T extends readonly [
    infer H extends boolean,
    ...(infer R extends boolean[]),
]
    ? H extends true ? CountTrue<R, [0, ...Acc]> : CountTrue<R, Acc>
    : Acc["length"]

Count the number of true values in a boolean tuple.

Type Parameters

T extends readonly boolean[]
Tuple of boolean values
Acc extends any[] = []

Remarks

Evaluates the tuple at the type level and returns a numeric literal. Useful as a building block for higher-order conditional helpers.

Example

type A = CountTrue< [ true, false, true ] >;  // 2
type B = CountTrue< [ false, false ] >;       // 0

Type Alias CountTrue<T, Acc>

Type Parameters

Remarks

Example

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