REPL

REPL stands for "read-eval-print loop". It's a common type of program that allows for interactivity. You type in a command, and the program evaluates it and prints the result. You can then type in another command, and so on.

Your native terminal's command line is a REPL! Our Pokedex will also be a REPL. In this step, we're just going to build the bones of the REPL: a loop that parses and cleans an input and prints the first word back to the user. Here is what your program should be able to do after this step:

> npm run dev
Pokedex > help me
help
Pokedex > Exit
exit
Pokedex > WHAT even is a pokeman?
what

Pokedex > is our own custom command line prompt. The program waited and recorded my input (in the first instance, help me) and didn't continue until I pressed enter.

Assignment

Remove your "Hello, World!" logic. Replace it with the following REPL logic.

Use .js extensions when importing files. We're using a bare-bones setup without a bundler, so Node can't import .ts. For example, this is my main.ts:

// repl.js actually refers to repl.ts
import { startREPL } from "./repl.js";

function main() {
  startREPL();
}

main();

Create an Interface for reading input. You'll need to specify:
- input: a readable stream (use process.stdin)
- output: a writable stream (use process.stdout)
- prompt: a string to print to output whenever rl.prompt() is called
Use the interface's .prompt() method to display the prompt.
Use the interface's .on("line", callback) method to listen for input. The callback should:
- Use your cleanInput function to parse the input into an array of words
- If the input is empty, call .prompt() to give the user back control to type another command and exit the callback
- Otherwise, print the first word back to the user in this format: Your command was: <first word>
- Call .prompt() to give the user back control to type another command
Test your program. Here's my example session:

wagslane@MacBook-Pro-2 pokedexcli % npm run dev
Pokedex > well hello there
Your command was: well
Pokedex > Hello there
Your command was: hello
Pokedex > POKEMON was underrated
Your command was: pokemon

You can terminate the program by pressing ctrl+c.

Run the CLI again and tee the output (which copies the stdout) to a new file called repl.log (and .gitignore the log).

npm run dev | tee repl.log

Use this as the first input: CHARMANDER is better than bulbasaur.
Use this as the second input: Pikachu is kinda mean to ash.
Terminate the program by pressing ctrl+c.

Run and submit the CLI tests.