# discord-haskell [](https://app.travis-ci.com/github/aquarial/discord-haskell) [](https://hackage.haskell.org/package/discord-haskell)
Build that discord bot in Haskell! Also checkout the [calamity](https://github.com/nitros12/calamity)
haskell discord library for a more advanced interface than `discord-haskell`.
This is an example bot that replies "pong" to messages that start with "ping".
```haskell
{-# LANGUAGE OverloadedStrings #-} -- allows "string literals" to be Text
import Control.Monad (when, void)
import Data.Text (isPrefixOf, toLower, Text)
import qualified Data.Text.IO as TIO
import UnliftIO.Concurrent
import Discord
import Discord.Types
import qualified Discord.Requests as R
-- | Replies "pong" to every message that starts with "ping"
pingpongExample :: IO ()
pingpongExample = do userFacingError <- runDiscord $ def
{ discordToken = "Bot ZZZZZZZZZZZZZZZZZZZ"
, discordOnEvent = eventHandler }
TIO.putStrLn userFacingError
eventHandler :: Event -> DiscordHandler ()
eventHandler event = case event of
MessageCreate m -> when (not (fromBot m) && isPing m) $ do
void $ restCall (R.CreateReaction (messageChannel m, messageId m) "eyes")
threadDelay (2 * 10^6)
void $ restCall (R.CreateMessage (messageChannel m) "Pong!")
_ -> return ()
fromBot :: Message -> Bool
fromBot = userIsBot . messageAuthor
isPing :: Message -> Bool
isPing = ("ping" `isPrefixOf`) . toLower . messageText
```
```
-- ping-pong.cabal
executable haskell-bot
main-is: src/Main.hs
default-language: Haskell2010
ghc-options: -threaded
build-depends: base
, text
, unliftio
, discord-haskell
```
### Biggest TODOs
- [ ] APIv9
- [x] rewrite eventloop [issue 70](https://github.com/aquarial/discord-haskell/issues/70)
- [ ] Event type includes roles and other cached info
- [ ] higher level bot interface? easier to add state and stuff
### Installing
discord-haskell is on hosted on hackage at https://hackage.haskell.org/package/discord-haskell,
In `stack.yaml`
```yaml
extra-deps:
- emoji-0.1.0.2
- discord-haskell-VERSION
```
In `project.cabal`
```cabal
executable haskell-bot
main-is: src/Main.hs
default-language: Haskell2010
ghc-options: -threaded
build-depends: base
, text
, discord-haskell
```
For a more complete example with various options go to
[Installing the Library](https://github.com/aquarial/discord-haskell/wiki/Installing-the-Library) wiki page
Also take a look at
[Creating your first Bot](https://github.com/aquarial/discord-haskell/wiki/Creating-your-first-Bot)
for some help setting up your bot token
### Emoji
For single character Emoji you can use the unicode name ("eyes", "fire", etc).
For multi-character Emoji you must use the discord format. Type `\:emoji:` into
a discord chat and paste that into the Text
For example `:thumbsup::skin-tone-3:` is `"👍\127997"`.
A custom emoji will look like `<name:id_number>` or `name:id_number`.
See [examples/ping-pong.hs](https://github.com/aquarial/discord-haskell/blob/master/examples/ping-pong.hs)
for a `CreateReaction` request in use.
### Embeds
Embeds are special messages with boarders and images. [Example embed created by discord-haskell](./examples/embed-photo.jpg)
The `Embed` record (and sub-records) store embed data received from Discord.
The `CreateEmbed` record stores data when we want to create an embed.
`CreateEmbed` has a `Default` instance, so you only need to specify the fields you use:
```haskell
_ <- restCall (R.CreateMessageEmbed <channel_id> "Pong!" $
def { createEmbedTitle = "Pong Embed"
, createEmbedImage = Just $ CreateEmbedImageUpload <bytestring>
, createEmbedThumbnail = Just $ CreateEmbedImageUrl
"https://avatars2.githubusercontent.com/u/37496339"
})
```
Uploading a file each time is slow, prefer uploading images to a hosting site like imgur.com, and then referencing them.
### Limitations
The following features are not implemented:
- Voice & Audio
- Authenticating with a user token
### Debugging
Always print the userFacingError Text returned from `runDiscord`. I use this to record
errors that cannot be recovered from.
If something else goes wrong with the library please open an issue. It is helpful,
but not always necessary, to attach a log of what's going on when the library
crashes.
Assign a handler to the `discordOnLog :: Text -> IO ()` to print info as it happens.
Remember to remove sensitive information before posting.
### Getting Help
#### Official discord docs
For a list of rest requests, gateway events, and gateway sendables go to the
[official discord documentation](https://discord.com/developers/docs/intro)
The rest requests line up very closely. The documentation lists
[Get Channel](https://discord.com/developers/docs/resources/channel#get-channel)
and discord-haskell has `GetChannel :: ChannelId -> ChannelRequest Channel`. Same for gateway `Event`s.
#### Examples
The [examples](https://github.com/aquarial/discord-haskell/tree/master/examples) were crafted
to display a variety of use cases. Read them with care.
#### Open an Issue
For deeper questions about how the library functions, feel free to open an issue.
#### Discord server
Coming sometime!