mapSecond
import { mapSecond } from "https://github.gh-proxy.cn/raw.githubusercontent.com/baetheus/fun/main/async_either.ts";Apply a function to the Left value of an AsyncEither.
@example
import * as AE from "./async_either.ts";
import { pipe } from "./fn.ts";
const result = pipe(
AE.left("error"),
AE.mapSecond(e => `Error: ${e}`)
);
const value = await result(); // Left("Error: error")