Simple signup function using FP-TS

// user-controller.ts
import argon2 from "argon2";
import * as E from "fp-ts/Either";
import { flow, pipe } from "fp-ts/lib/function";
import * as TE from "fp-ts/TaskEither";
import {
    UserProfile,
    UserProfileRepository,
} from "../db/entities/user_profile";

function hashPassword(plainPassword: string): TE.TaskEither<Error, string> {
    return () =>
        argon2
            .hash(plainPassword)
            .then((hashed) => E.right(hashed))
            .catch((e) => E.left(e));
}

export function signup(
    userName: string,
    email: string,
    password: string
): TE.TaskEither<Error, UserProfile> {
    const makeUserProfile = (hashed: string) => {
        return new UserProfile({ userName, email, userPassword: hashed });
    };
    //the reason to "chain" is because the nested TaskEithers need to be flattened
    const program = flow(
        hashPassword,
        TE.chain(flow(makeUserProfile, UserProfileRepository.insertProfile))
    );
    return pipe(password, program);
}

// user-router.ts
import express from "express";
import { pipe } from "fp-ts/lib/function";
import { signup } from "../controllers/user-controller";
import * as E from "fp-ts/lib/Either";

router.post("/signup", async (req, res) => {
    const { username, password } = req.body;
    // we have to call the asynchronous Task
    const userE = await signup(username, username, password)();
    pipe(
        userE,
        E.bimap(
            (e) => res.send({ ok: false, message: e.message }),
            (user) =>
                res.send({
                    ok: true,
                    message: `user ${user.userName} registered `,
                })
        )
    );
});