import { assertEquals, test } from "Test"
import { Just, Nothing } from "Maybe"
import { Right, Left } from "Either"
import { mapL } from "./Functor"

test("mapL - Maybe", () => pipe(
  mapL(3),
  assertEquals($, Just(3)),
)(Just(1)))

test("mapL - Nothing", () => assertEquals(mapL(3, Nothing), Nothing))

test("mapL - List", () => assertEquals(mapL(99, [1, 2, 3]), [99, 99, 99]))

test("mapL - Either Right", () => assertEquals(mapL(5, Right("ok")), Right(5)))
test("mapL - Either Left", () => assertEquals(mapL(5, Left("err")), Left("err")))

// Functor laws: identity
test("map identity - Maybe", () => assertEquals(map((x) => x, Just(3)), Just(3)))
test("map identity - List", () => assertEquals(map((x) => x, [1, 2, 3]), [1, 2, 3]))

// Functor laws: composition
test("map composition - Maybe", () => {
  f = (x) => x + 1
  g = (x) => x * 2
  return assertEquals(
    map((x) => f(g(x)), Just(3)),
    map(f, map(g, Just(3))),
  )
})
test("map composition - List", () => {
  f = (x) => x + 1
  g = (x) => x * 2
  return assertEquals(
    map((x) => f(g(x)), [1, 2, 3]),
    map(f, map(g, [1, 2, 3])),
  )
})