Lumen Reference

A quick lookup for every event, function, node, setting, and error message. If you are learning Lumen for the first time, start with the Guide instead.

Download this reference as a Word document (.docx)

Guide Reference

Events

Event	Category	Trigger text	Exposes	Fires when
`message`	Messages	Required, e.g. `"!hello"`	`message`, `user`	A message starts with the trigger text
`member_join`	Server Events	None	`member`	Someone joins the server
`member_leave`	Server Events	None	`member`	Someone leaves or is removed from the server
`reaction_add`	Reactions	None	`user`, `reaction`	Someone adds a reaction to a message

Events with no trigger text fire on their own, so a server can only have one command per event of that kind. message commands each need a unique trigger, so a server can have as many as it wants.

Language Functions

Always available, regardless of what the bot itself provides.

Function	What it does	Example
`length(x)`	Length of a string, list, or dict	`length("hello")` → 5
`keys(d)`	List of a dict's keys	`keys({"a": 1})` → `["a"]`
`upper(s)`	Uppercase a string	`upper("hi")` → "HI"
`lower(s)`	Lowercase a string	`lower("HI")` → "hi"
`str(x)`	Convert anything to text	`str(42)` → "42"
`int(x)`	Convert text or number to a whole number	`int("7")` → 7
`float(x)`	Convert text or number to a decimal	`float("2.5")` → 2.5
`split(s, sep)`	Split a string into a list	`split("a,b", ",")` → `["a", "b"]`
`join(list, sep)`	Join a list into one string	`join(["a", "b"], "-")` → "a-b"
`contains?(x, v)`	Does a string, list, or dict contain v?	`contains?([1,2], 2)` → true
`index_of(x, v)`	Position of v, or nil if not found	`index_of("hi", "i")` → 1
`push(list, v)`	Add v to the end of a list, in place	`push(list, 3)`
`pop(list)`	Remove and return the last item, in place	`pop(list)` → 3

Bot Functions

Provided by the bot itself. This list can grow over time.

Function	What it does
`send(text)`	Posts a message to the channel the trigger came from
`random(min, max)`	A random whole number between min and max, inclusive
`wait(seconds)`	Pauses briefly before continuing, capped at a few seconds
`react(emoji)`	Reacts to the trigger message with an emoji

Node Editor Blocks

Available in the Blocks view of the command editor. "All events" means the node works no matter which event the command uses.

Node	What it does	Works with
Say something	Sends a message back to the channel	All events
Random number	Picks a random number and stores it in a variable you name	All events
Wait	Pauses before the next node runs	All events
Admin check	Sends one message to admins and another to everyone else	Message, Reaction
If message contains a word	Checks whether the message text contains a word, with an optional otherwise message	Message
Random message from a list	Picks one line at random from a list you type, one message per line	All events
Repeat a message	Sends the same message a fixed number of times in a row	All events
Shout something	Sends a message in ALL CAPS	All events
Whisper something	Sends a message in lowercase	All events
Reply with the message's length	Counts the characters in the message and includes the count in a reply	Message
Only reply sometimes	Rolls a percentage chance before sending a message	All events
If the message is exactly	Like "contains a word", but requires an exact whole-message match	Message
Only for a specific person	Sends a different message depending on the sender's exact username	Message, Reaction
Remember some text	Stores text in a variable you name, to reuse in later nodes	All events
Remember a number	Stores a number in a variable you name, to reuse in later nodes	All events
Wait a random amount of time	Pauses for a random number of seconds within a range you set	All events
Repeat a random number of times	Like "Repeat a message", but the number of repeats is randomized each run	All events
Reply with the word count	Counts the words (not characters) in the message and includes the count in a reply	Message
Do some math and reply	Adds, subtracts, multiplies, or divides two numbers and includes the result in a reply	All events
React with an emoji	Reacts to the trigger message (or the reacted-to message, on a reaction event) with an emoji	Message, Reaction

The palette in the editor only shows nodes that make sense for whichever event is currently selected, so you will not see every row above at once.

Server Settings

Setting	What it controls
Manager roles	Which roles, beyond the server owner and Administrator/Manage Server, can create and edit commands
Command prefix	The prefix the built-in `!ping`, `!info`, and `!config` commands respond to. Does not affect your own commands' trigger text
Built-in commands	Turns `ping`, `info`, and `config` on or off individually for this server
Error log channel	Where the bot posts a short notice if a saved command hits an error while running

Built-in Bot Commands

Command	What it does
`!ping`	Replies with the bot's current latency
`!info`	Replies with how many custom commands are enabled in the server
`!config`	Replies with a link to this server's dashboard

The ! shown here is the default prefix; it changes if you set a custom one in Server Settings.

Error Messages

Message	What it means
`Unexpected token ... at line N`	A typo or missing `end`, quote, or bracket near that line
`Undefined variable 'x'`	A variable was used before it was assigned a value
`Expected a number, got String`	Math was attempted on text, check `int()` or `float()`
has no `on message("...")` handler matching the trigger	The trigger word does not match the `on message(...)` line (or, for events like `member_join`, the handler needs to be a zero-argument `on member_join()`)
`Script exceeded ... step limit`	Almost always an infinite `while` loop, check the loop's condition
"This command's code doesn't match a pattern the block editor understands yet"	The Code view has something (a loop, a custom function, hand-written logic) that the Blocks view cannot represent. The code is left untouched