API reference › @evolu/common › Set › mapSet

Call Signature

function mapSet<T, U>(
  set: NonEmptyReadonlySet<T>,
  mapper: (item: T) => U,
): NonEmptyReadonlySet<U>;

Defined in: packages/common/src/Set.ts:231

Maps a set using a mapper function, returning a new readonly set.

Preserves non-empty type.

Note: If the mapper produces duplicate values, the resulting set will have fewer elements.

Mapping non-empty sets

import {
  assertEqual,
  assertType,
  createSet,
  mapSet,
  type NonEmptyReadonlySet,
} from "@evolu/common";

const original = createSet([1, 2, 3]);
const doubled = mapSet(original, (x) => x * 2);
const parity = mapSet(original, (x) => x % 2);

assertType<NonEmptyReadonlySet<number>, typeof doubled>();
assertEqual(doubled, new Set([2, 4, 6]));
assertEqual(parity, new Set([1, 0]));

Call Signature

function mapSet<T, U>(
  set: ReadonlySet<T>,
  mapper: (item: T) => U,
): ReadonlySet<U>;

Defined in: packages/common/src/Set.ts:236

Possibly empty set.

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