Trying out fp-ts ReaderT

index.ts

import * as readerT from "fp-ts/lib/ReaderT"
import { future } from "fp-ts-fluture/lib/Future"
import { of, reject, FutureInstance as Future } from "fluture"
import { identity } from "fp-ts/lib/function";

type Env = {
  locale: string
}

const env$: Env = {
  locale: "en"
}

type Product = {
  productId: number,
  price?: number,
  names: {
    en: string,
    fr: string
  }
}
type LocalizedProduct = {
  productId: number,
  price?: number,
  name: string
}

const getProduct: 
  (id: number) => 
  Future<never, Product> = 
  (productId: number) => of({ productId, names: { en: "English shirt", fr: "French shirt" } })

const getProductPrices:
  (product: Product) =>
  Future<never, Product> = 
  (product: Product) => of({ ...product, price: 12.00 })

const chooseLocale:
  (locale: string) =>
  (product: Product) =>
  LocalizedProduct = 
  (locale: string) => (product: Product) => ({ productId: product.productId, price: product.price, name: product.names[locale] })

const getLocalizedProduct:
  (productId: number) =>
  (env: Env) =>
  Future<never, LocalizedProduct> =
  (productId: number) => (env: Env) => getProduct(productId).chain(getProductPrices).map(chooseLocale(env.locale))

const productId = 1234
const readerFluture = readerT.getReaderT2v(future)
const envR = readerFluture.map(getLocalizedProduct(productId), identity)
const f = envR(env$)
f.fork(
  err => console.dir(err),
  res => {
    console.dir(res)
    console.dir('^^^ res')
  }
)

package.json

{
  "name": "readert-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "fluture": "^11.0.2",
    "fp-ts": "^1.19.3",
    "fp-ts-fluture": "^0.4.1"
  }
}