Two ways to use Env

1-echo-console.ts

import { co, unsafeRun, resumeLater, resumeNow, use, Resume, op } from '../src'
import { EOL } from 'os'
import { createInterface } from 'readline'

type Print = { print(s: string): Resume<void> }
const print = (s: string) => op<Print>(c => c.print(s))

type Read = { read(): Resume<string> }
const read = op<Read>(c => c.read())

const main = co(function* () {
  while(true) {
    yield* print('> ')
    const s = yield* read
    yield* print(`${s}${EOL}`)
  }
})

const capabilities = {
  print: (s: string): Resume<void> =>
    resumeNow(void process.stdout.write(s)),

  read: (): Resume<string> =>
    resumeLater(k => {
      const handler = (s: string): void => {
        readline.close()
        k(s)
      }
      const readline = createInterface({ input: process.stdin }).once('line', handler)  
      return () => readline.removeListener('line', handler).close()
    })
}
const m = use(main(), capabilities)

unsafeRun(m)

2-echo-console.ts

import { co, unsafeRun, resumeLater, resumeNow, use, op } from '../src'
import { EOL } from 'os'
import { createInterface, Interface } from 'readline'

type Console = { stdout: typeof process.stdout }
const print = (s: string) => op<Console, void>(c => resumeNow(void c.stdout.write(s)))

type Readline = { readline: Interface }
const read = op<Readline, string>(c => resumeLater(k => {
  c.readline.once('line', k)
  return () => c.readline.removeListener('line', k)
}))

const main = co(function* () {
  while (true) {  
    yield* print('> ')
    const s = yield* read
    yield* print(`${s}${EOL}`)
  }
})

const environment = {
  stdout: process.stdout,
  readline: createInterface({ input: process.stdin })
}

const m = use(main(), environment)

unsafeRun(m)