Telega

A Gleam library for the Telegram Bot API.

It provides

• an interface to the Telegram Bot HTTP-based APIs telega/api
• adapter to use with wisp
• session bot implementation
• conversation implementation

Quick start

If you are new to Telegram bots, read the official Introduction for Developers written by the Telegram team.

First, visit @BotFather to create a new bot. Copy the token and save it for later.

Initiate a gleam project and add telega and wisp as a dependencies:

$ gleam new first_tg_bot
$ cd first_tg_bot
$ gleam add telega wisp mist gleam_erlang

Replace the first_tg_bot.gleam file content with the following code:

import gleam/erlang/process
import gleam/option.{None}
import gleam/result
import mist
import telega
import telega/adapters/wisp as telega_wisp
import telega/reply
import telega/update.{CommandUpdate, TextUpdate}
import wisp

fn handle_request(bot, req) {
  use <- telega_wisp.handle_bot(req, bot)
  wisp.not_found()
}

fn echo_handler(ctx) {
  use <- telega.log_context(ctx, "echo")

  case ctx.update {
    TextUpdate(text:, ..) -> reply.with_text(ctx, text)
    CommandUpdate(command:, ..) -> reply.with_text(ctx, command.text)
    _ -> Error("No text message")
  }
  |> result.map(fn(_) { Nil })
}

pub fn main() {
  wisp.configure_logger()

  let assert Ok(bot) =
    telega.new(
      token: "your bot token from @BotFather",
      url: "your bot url",
      webhook_path: "secret path",
      secret_token: None,
    )
    |> telega.handle_all(echo_handler)
    |> telega.init_nil_session

  let assert Ok(_) =
    wisp.mist_handler(handle_request(bot, _), wisp.random_string(64))
    |> mist.new
    |> mist.port(8000)
    |> mist.start_http

  process.sleep_forever()
}

Replace "your bot token from @BotFather" with the token you received from the BotFather. Set the url and webhook_path to your server's URL and the desired path for the webhook. If you don't have a server yet, you can use ngrok or localtunne to create a tunnel to your local machine.

Then run the bot:

$ gleam run

And it will echo all received text messages.

Congratulations! You just wrote a Telegram bot :)

Examples

Other examples can be found in the examples directory.

Development

gleam run   # Run the project
gleam test  # Run the tests
gleam shell # Run an Erlang shell