Function f

packages/effect/test/Option.test.ts:130–132

(
      s: string | number
    )

  it("toRefinement", () => {
    const f = (
      s: string | number
    ): Option.Option<string> => (typeof s === "string" ? Option.some(s) : Option.none())
    const isString = Option.toRefinement(f)

    assertTrue(isString("s"))