is-blackhole/fp-ts-notes

fp-ts notes

TE.tapError: replace error with another one, right is not affected or can be changed

async function testTapError() {
const _testTapError = (te: TE.TaskEither<string, string>) =>
  pipe(
    te,
    TE.tapError((e) => {
      switch (e) {
        case "error to replace":
          return TE.left("replaced error");
        case "go right":
          return TE.right(e);
        default:
          return TE.left(e);
      }
    })
  );

assert.deepStrictEqual(await _testTapError(TE.right("ok"))(), E.right("ok"));
assert.deepStrictEqual(await _testTapError(TE.left("error to replace"))(), E.left("replaced error"));
assert.deepStrictEqual(await _testTapError(TE.left("passed error"))(), E.left("passed error"));
assert.deepStrictEqual(await _testTapError(TE.left("go right"))(), E.left("go right"));
}

testTapError();