skLambda

!Cover

A Skript addon that lets you treat behavior as a value, and cut a lot of boilerplate while you're at it. It adds:

1. Lambdas: Small functions you save in a variable, pass around, and run later. They support closures, default parameters, and piping.
2. Predicates: Reusable yes/no tests you can combine with all, any, or none, or count how many pass.
3. List operations: Map, reduce, scan, zip, sort, highest/lowest, and paging, without writing the loops yourself.
4. Self-cleaning listeners: Temporary event listeners scoped to one player or command, with a timer, a hit count, and lifecycle callbacks. They stop themselves.
5. Async: Run a lambda off the main thread with futures, wait for an event or result without freezing the server, and watch a value or condition.

Links

Example: same task, two ways

The task: tell the player to mine 10 stone in 30 seconds. Give a diamond if they finish, say "too slow" if they don't.

Without skLambda

on break of stone:
    if {challenge::%player%} is not set:
        stop
    add 1 to {challenge::progress::%player%}
    if {challenge::progress::%player%} >= 10:
        send "you did it!" to player
        give 1 diamond to player
        delete {challenge::%player%}
        delete {challenge::progress::%player%}

command /challenge:
    trigger:
        set {challenge::%player%} to true
        set {challenge::progress::%player%} to 0
        send "mine 10 stone in 30s" to player
        wait 30 seconds
        if {challenge::%player%} is set:
            send "too slow" to player
            delete {challenge::%player%}
            delete {challenge::progress::%player%}

Lots to do by hand: a global on break of stone that runs for every player, a flag variable, a counter variable, a separate wait for the timeout, and delete lines everywhere to clean up.

With skLambda

command /challenge:
    trigger:
        send "mine 10 stone in 30s" to player
        listen for block break where event-block is stone:
            countdown: 30 seconds
            triggers: 10
            every 1 second:
                send action bar "%remaining triggers% left — %remaining countdown%" to event-player
            on completion:
                send "you did it!" to event-player
                give 1 diamond to event-player
            on timeout:
                send "too slow!" to event-player

That's it. The listener belongs to this one command run. The counter, the timer, and the live action-bar readout are built in, and when it finishes or times out, it cleans up by itself.

More than listeners

Save a test and run it over a list. Predicates pair with Skript's own filter, and list operations skip the loop:

# keep only the players who are AFK
set {_afk} to lambda (p: player): {_p}'s idle time > 5 minutes
set {_idle::*} to all players where [{_afk} passes for input]

# score every player with a lambda, grab the winner
set {_score} to lambda (p: player) -> number:
    return {_p}'s level
set {_mvp} to highest of all players by {_score}

New in 1.3.0, you can pause a trigger and wait without freezing the server:

command /confirm:
    trigger:
        send "type 'yes' in chat within 15s to confirm." to player
        wait for next chat where player is sender within 15 seconds:
            if message is "yes":
                send "confirmed!" to player
            on timeout:
                send "cancelled — no reply." to player

The trigger picks up right where it left off when the player chats, and the server keeps ticking the whole time. You can also wait for a background job (future of calling lambda ...) or watch a value or condition and react only when it changes.

Full guides and dozens of runnable examples are on the wiki.

Requirements

• Paper 1.21.1+
• Skript 2.15+

License

MIT

Stats

skLambda uses bStats for anonymous usage stats. You can opt out in plugins/bStats/config.yml.

NOTES

if you experience any problems, let me know on discord eult, discord server