Function scan

scan<const Ar extends readonly unknown[], S>(
    array: Ar,
    reducer: (
        accumulator: S,
        currentValue: Ar[number],
        currentIndex: ArrayIndex<Ar>,
    ) => S,
    init: S,
): readonly [S, S]

Returns an array of successively reduced values from an array.

Type Parameters

const Ar extends readonly unknown[]
S

Parameters

array: Ar
reducer: (accumulator: S, currentValue: Ar[number], currentIndex: ArrayIndex<Ar>) => S
init: S

Returns readonly [S, S]

Example

const changes = [5, -2, 3] as const;

const runningTotals = Arr.scan(changes, (total, change) => total + change, 0);
const runningTotalsFromCurried = Arr.scan(
  (total: number, change: number) => total + change,
  10,
)([-5, 15]);

const expectedTotals = [0, 5, 3, 6] as const;
const expectedCurriedTotals = [10, 5, 20] as const;

assert.deepStrictEqual(runningTotals, expectedTotals);
assert.deepStrictEqual(runningTotalsFromCurried, expectedCurriedTotals);

scan<E, S>(
reducer: (accumulator: S, currentValue: E, currentIndex: Uint32) => S,
init: S,
): (array: readonly E[]) => readonly [S, S]

Returns an array of successively reduced values from an array.

Type Parameters

Parameters

reducer: (accumulator: S, currentValue: E, currentIndex: Uint32) => S
init: S

Returns (array: readonly E[]) => readonly [S, S]

Example

const changes = [5, -2, 3] as const;

const runningTotals = Arr.scan(changes, (total, change) => total + change, 0);
const runningTotalsFromCurried = Arr.scan(
  (total: number, change: number) => total + change,
  10,
)([-5, 15]);

const expectedTotals = [0, 5, 3, 6] as const;
const expectedCurriedTotals = [10, 5, 20] as const;

assert.deepStrictEqual(runningTotals, expectedTotals);
assert.deepStrictEqual(runningTotalsFromCurried, expectedCurriedTotals);

Function scan

Type Parameters

Parameters

Returns readonly [S, S]

Example

Type Parameters

Parameters

Returns (array: readonly E[]) => readonly [S, S]

Example

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