R16 - A Discord Trick Bot

8.0

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R16 - A Discord Trick Bot

R16 is a "trick bot" for Discord. It saves snippets of code, which can then be recalled and executed on user-provided input.

1 The Trick Environment

Tricks are stored as plain text, and invoked in a sandbox from racket/sandbox.

The following symbols are available in the trick context:

All symbols from the threading-lib package are available for convenience.

procedure
(make-attachment payload name mime) → any/c
  payload : bytes?
  name : (or/c string? bytes?)
  mime : (or/c symbol? string? bytes?)

Creates an attachment with payload payload, filename name, and MIME-type mime. This opaque object must be returned from the trick to be sent to Discord. If more than one attachment is returned, an unspecified one is sent.

procedure
(call-trick name argument) → any/c
name : (or/c symbol? string?)
argument : any/c

Invokes another trick named by name and return its result. If argument is #f, then an empty string is passed to the subtrick. Otherwise, (~a argument) is passed.

value
message-contents : string?

Full text of the message that invoked this trick.

value
string-args : string?

Text of the message after the bot command, as a string.

procedure
(read-args) → (or/c (listof any/c) #f)

Function that returns string-args, but as a list of datums read by read. If there is a read failure, #f is returned.

procedure
(emote-lookup name) → (or/c string? #f)
name : string?

Function that returns the ID for emote with name name, or #f if it doesn’t exist.

procedure
(emote-image id) → (or/c bytes? #f)
id : string?

Function that returns the PNG data of the emote with ID id, or #f if it doesn’t exist.

procedure
(read-storage type) → any/c
type : (or/c 'guild 'channel 'user)

Reads "trick-local storage" name and return its result, or #f if the result is uninitialized.

A trick’s "trick-local storage" can be per-guild, per-channel, or per-user.

This will always return #f for the eval command.

procedure
(write-storage type data) → boolean?
type : (or/c 'guild 'channel 'user)
data : any/c

Writes data to the trick’s "trick-local storage," overwriting any existing value, and returns whether the write succeeded. All data supported by write can be written.

Note that "trick-local storage" is transient and does not currently persist across bot restarts.

A trick’s "trick-local storage" can be per-guild, per-channel, or per-user; each type of storage has its own limitation on size:

Type		Size Limit
guild		64kb
channel		8kb
user		2kb

This will always be a no-op when invoked from the eval command.

procedure
(delete-caller) → void?

Thunk that deletes the message that invoked this sandbox.

value
parent-context : (or/c (hash/c symbol? any/c) #f)

Mapping of all the above symbols for the trick calling this one, or #f if this trick is the top level invocation.

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