shmup/mud

2026-02-07 19:31:38 -05:00

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MUD Scripting Languages Reference

this document catalogs real-world MUD scripting DSLs with code examples. the goal is to study how different games let builders create interactive objects, NPCs, and behaviors -- to inform our own DSL design later.

for each language, we show real examples from existing MUDs, then implement two test scenarios:

scenario A - talking parrot: an NPC that listens to player speech, remembers what it hears, and randomly repeats things on a timer.

scenario B - tv set: an interactive object with a pull knob (on/off toggle) and spin dial (channel selector). when on, it periodically shows messages from the current channel (weather, news, etc).

1. MOO Verb Language

object-oriented, prototype-based. everything is an object with properties and verbs. fork schedules delayed tasks. :tell() sends messages. :announce_all() broadcasts to the room.

real examples

wind-up toy (classic timer pattern):

@verb toy:wind this none none
@program toy:wind
if (this.wound < this.maximum)
  this.wound = this.wound + 2;
  player:tell("You wind up the ", this.name, ".");
  player.location:announce(player.name, " winds up the ", this.name, ".");
endif
.

@verb toy:drop this none none
@program toy:drop
pass(@args);
if (this.wound)
  this.location:announce_all(this.name, " ", this.startup_msg);
  for x in [1..this.wound]
    fork (x * 15)
      this.location:announce_all(this.name, " ", this.continue_msg);
      this.wound = this.wound - 1;
    endfork
  endfor
endif
.

pet following + command response:

@verb pet:follow any with this
@program pet:follow
if ((player in this.masters) || (!this.masters))
  who = $string_utils:match_player(dobjstr);
  if (who == $failed_match)
    player:tell(this.name, " looks confused...");
  else
    this.tofollow = who;
    this.on_track = 1;
  endif
endif
.

interactive object (kleenex with conditional responses):

@verb kleenex:wipe any with this
@program kleenex:wipe
if (dobjstr == "nose")
  player:tell("Okay. You wipe your nose with the ", this.name, ".");
  player.location:announce(player.name, " has the sniffles.");
else
  player:tell("Okay. You wipe ", dobjstr, " with the ", this.name, ".");
endif
.

random message generation:

first = {"You discover that", "To your surprise,", "Unbelievably,"}[random(3)];
last = {" the cat is alive.", " the cat is dead."}[random(2)];
player:tell(first, last);

parrot implementation

@create $thing named parrot
@property parrot.memories {}
@property parrot.max_memories 10
@property parrot.chatty 1

@verb parrot:setup_listener this none this
@program parrot:setup_listener
" Called when parrot is placed in a room - starts the chatter loop ";
if (this.chatty)
  fork (random(60) + 30)
    this:chatter();
  endfork
endif
.

@verb parrot:chatter this none this
@program parrot:chatter
" Randomly repeats something it heard ";
if (this.location && length(this.memories) > 0)
  phrase = this.memories[random(length(this.memories))];
  this.location:announce_all(this.name, " squawks: \"", phrase, "\"");
endif
if (this.chatty)
  fork (random(60) + 30)
    this:chatter();
  endfork
endif
.

@verb parrot:hear this none this
@program parrot:hear
" Override of standard :hear verb to capture speech ";
pass(@args);
what = args[1];
who = args[2];
if (who != this && length(what) > 0)
  this.memories = {@this.memories, what};
  if (length(this.memories) > this.max_memories)
    this.memories = this.memories[2..$];
  endif
endif
.

@verb parrot:moveto this to any
@program parrot:moveto
pass(@args);
if (valid(this.location))
  this:setup_listener();
endif
.

tv implementation

@create $thing named television
@property tv.is_on 0
@property tv.channel 1
@property tv.channels {{"The weather is sunny.", "Clouds rolling in.", "Expect rain tonight."}, {"Breaking news: mayor resigns!", "Sports: home team wins!", "Traffic is heavy downtown."}, {"Soap opera: dramatic pause...", "Commercial: buy now!", "Sitcom: laugh track plays."}}
@property tv.broadcasting 0

@verb tv:pull this none none
@program tv:pull
if (this.is_on)
  this.is_on = 0;
  this.broadcasting = 0;
  player:tell("You pull the knob. The ", this.name, " turns off with a click.");
  player.location:announce(player.name, " turns off the ", this.name, ".");
else
  this.is_on = 1;
  player:tell("You pull the knob. The ", this.name, " flickers to life.");
  player.location:announce(player.name, " turns on the ", this.name, ".");
  this:start_broadcast();
endif
.

@verb tv:turn this none none
@verb tv:spin this none none
@program tv:turn
if (!this.is_on)
  player:tell("The ", this.name, " is off.");
  return;
endif
this.channel = (this.channel % length(this.channels)) + 1;
player:tell("You turn the dial. Now on channel ", this.channel, ".");
player.location:announce(player.name, " changes the channel.");
.

@verb tv:start_broadcast this none this
@program tv:start_broadcast
if (!this.broadcasting && this.is_on)
  this.broadcasting = 1;
  fork (15)
    this:broadcast();
  endfork
endif
.

@verb tv:broadcast this none this
@program tv:broadcast
if (this.is_on && valid(this.location))
  msgs = this.channels[this.channel];
  msg = msgs[random(length(msgs))];
  this.location:announce_all("The ", this.name, " shows: ", msg);
  fork (15)
    this:broadcast();
  endfork
else
  this.broadcasting = 0;
endif
.

@verb tv:moveto this to any
@program tv:moveto
this.broadcasting = 0;
pass(@args);
if (this.is_on && valid(this.location))
  this:start_broadcast();
endif
.

2. LPC (LPMud)

C-like, file-based OOP. key hooks: create() (init), init() (add_action for commands), heart_beat() (timer tick). objects inherit from standard library bases.

real examples

NPC scripting system (Lima):

create_script("lunch", ({
    step(SCRIPT_ACTION, "say Well, time for some lunch."),
    step(SCRIPT_WAIT, 5),
    step(SCRIPT_TRIGGER, "The elevator door opens.", "go northwest"),
    step(SCRIPT_DESC, "Harry, leaning against the elevator panel."),
    step(SCRIPT_ACTION, "emote stands up.@@say Guess it's time."),
}));

say-response NPC (Nightmare-Residuum):

void set_say_response(string match, string response) {
    __SayResponse[match] = response;
}
void handle_say_response(string message) {
    foreach (string match, string response in __SayResponse) {
        if (regexp(message, match)) {
            this_object()->handle_command("say " + response);
            return;
        }
    }
}

periodic random actions (Lima):

void set_actions(int delay, string *actions) {
   delay_time = delay;
   my_actions = actions;
   start_actions();
}

void actions() {
   if (!this_object()->query_target() && sizeof(my_actions))
      do_game_command(choice(my_actions));
   if (my_actions && query_listeners() && find_call_out("actions") == -1)
      call_out("actions", delay_time);
}

room chatter (Discworld):

room_chat(({ 120, 240, ({
    "A frog croaks.",
    "A revolting smell drifts from the rug.",
    "You hear distant thunder."
}) }));

parrot race definition (Discworld):

void setup() {
   set_name("parrot");
   set_long("A vicious, evil-looking parrot.\n");
   add_ac("feather_blow", "blunt", 10);
}
void set_unarmed_attacks(object thing) {
   thing->add_attack("beak", 50, ({ number / 2, 2, number / 2 }), "pierce", "unarmed", 0);
}

room with interactive lever/doorbell (Dead Souls):

void init() {
    ::init();
    add_action("aa_ring", "ring");
}
int aa_ring(string str) {
    write("DONG!\nYou ring a doorbell!\n");
    this_player()->SetProperty("rung_bell", 1);
    return 1;
}
int pre_north() {
    if (!this_player()->GetProperty("rung_bell")) {
        write("Ring the doorbell first!\n");
        return 0;
    }
    return 1;
}

Lima's react scripting mini-language:

@trigger The elevator door opens.
  go northwest
@endtrigger

@doevery 30 to 60
  say Anyone want to buy some fish?
@enddoevery

@if find gold here
  @action $N picks up the gold
  @move gold $self
@else
  say No gold here...
@endif

parrot implementation

// /domains/town/npc/parrot.c
#include <lib.h>

inherit LIVING;

string *memories;
int max_memories;
int next_chat;

void create() {
    ::create();
    set_name("parrot");
    set_short("a colorful parrot");
    set_long("A bright tropical parrot with green and red plumage. "
             "It watches you with intelligent eyes.");
    set_gender("neuter");
    set_race("bird");

    memories = ({});
    max_memories = 10;
    next_chat = 0;

    set_heart_beat(1);
}

void heart_beat() {
    ::heart_beat();

    if (!environment()) return;

    next_chat--;
    if (next_chat <= 0 && sizeof(memories) > 0) {
        string phrase = memories[random(sizeof(memories))];
        do_game_command("say " + phrase);
        next_chat = 30 + random(60); // 30-90 seconds
    }
}

void eventReceiveEmit(string message, object who) {
    string speech;

    // match "Foo says: blah" or "Foo says, \"blah\""
    if (sscanf(message, "%*s says: %s", speech) ||
        sscanf(message, "%*s says, \"%s\"", speech)) {
        if (who != this_object() && speech && strlen(speech) > 0) {
            memories += ({ speech });
            if (sizeof(memories) > max_memories) {
                memories = memories[1..];
            }
        }
    }
}

tv implementation

// /domains/town/obj/television.c
#include <lib.h>

inherit OBJECT;

int is_on;
int channel;
mapping channels;
int next_broadcast;

void create() {
    ::create();
    set_name("television");
    set_short("a vintage television set");
    set_long("An old black-and-white television with a pull knob and a dial. "
             "The screen is " + (is_on ? "glowing" : "dark") + ".");
    set_mass(5000);

    is_on = 0;
    channel = 1;
    channels = ([
        1: ({ "The weather is sunny.",
              "Clouds rolling in.",
              "Expect rain tonight." }),
        2: ({ "Breaking news: mayor resigns!",
              "Sports: home team wins!",
              "Traffic is heavy downtown." }),
        3: ({ "Soap opera: dramatic pause...",
              "Commercial: buy now!",
              "Sitcom: laugh track plays." })
    ]);
    next_broadcast = 0;

    set_heart_beat(1);
}

void init() {
    ::init();
    add_action("do_pull", "pull");
    add_action("do_turn", "turn");
    add_action("do_turn", "spin");
}

int do_pull(string str) {
    if (!str || !id(str)) return 0;

    if (is_on) {
        is_on = 0;
        write("You pull the knob. The television turns off with a click.");
        say(this_player()->query_cap_name() + " turns off the television.");
    } else {
        is_on = 1;
        write("You pull the knob. The television flickers to life.");
        say(this_player()->query_cap_name() + " turns on the television.");
        next_broadcast = 15;
    }

    set_long("An old black-and-white television with a pull knob and a dial. "
             "The screen is " + (is_on ? "glowing" : "dark") + ".");
    return 1;
}

int do_turn(string str) {
    if (!str || !id(str)) return 0;

    if (!is_on) {
        write("The television is off.");
        return 1;
    }

    channel = (channel % sizeof(channels)) + 1;
    write("You turn the dial. Now on channel " + channel + ".");
    say(this_player()->query_cap_name() + " changes the channel.");
    return 1;
}

void heart_beat() {
    ::heart_beat();

    if (!is_on || !environment()) return;

    next_broadcast--;
    if (next_broadcast <= 0) {
        string *msgs = channels[channel];
        string msg = msgs[random(sizeof(msgs))];
        environment()->eventPrint("The television shows: " + msg);
        next_broadcast = 15;
    }
}

3. DG Scripts (CircleMUD/TBAmud)

event-triggered scripts with %variable% substitutions. trigger types: greet, speech, random, command, fight, give, bribe, etc. scripts use if/else/end, wait, switch/case, %load%, %purge%.

real examples

quest NPC (greet trigger):

#1
Quest Offer~
0 g 100
~
if %actor.is_pc% && %direction% == south
  wait 1 sec
  say Can you help me, %actor.name%?
  wait 1 sec
  say An ogre has something of mine.
  say Please, bring me the wings.
end
~

magic eight ball (object command trigger):

#6
Magic Eight Ball~
1 c 2
shake~
switch %random.20%
  case 1
    %send% %actor% Outlook Good
  break
  case 2
    %send% %actor% Outlook Not So Good
  break
  case 3
    %send% %actor% Ask Again Later
  break
done
~

mynah bird (speech mimicry with variable storage!):

#1203
Mynah Bird~
0 d 100
*~
if %actor.is_pc%
  if %c%<20
    eval c 20
    global c
  end
  if !%speech.contains(!)%
    eval c (%c%)+1
    global c
    set %c% %speech%
    global %c%
    eval count %%random.%c%%%
    eval ans %%%count%%%
    wait %random.5%
    say %ans%
  end
end
~

guard bribe trigger:

#5
Guard Bribe~
0 m 1
~
if %amount% >= 10
  if %amount% > 10
    eval change %amount% - 10
    give %change% coin %actor.name%
  end
  say Thank you.
  unlock gateway
  open gateway
  wait 10 sec
  close gateway
  lock gateway
else
  say only %amount% coins, I require 10.
  give %amount% coin %actor.name%
end
~

parrot implementation

the mynah bird example above IS essentially the parrot scenario! it uses global variables %c% (counter) and %1%, %2%, etc (stored phrases). here's an annotated version:

#2001
Talking Parrot~
0 d 100
*~
* Speech trigger - fires on any speech in room
* Uses numbered global variables to store memories
if %actor.is_pc%
  * Initialize memory counter if needed
  if %c%<20
    eval c 20
    global c
  end
  * Only remember non-exclamatory speech
  if !%speech.contains(!)%
    * Increment counter
    eval c (%c%)+1
    global c
    * Store speech in numbered variable (%21%, %22%, etc)
    set %c% %speech%
    global %c%
    * Pick a random memory to repeat
    eval count %%random.%c%%%
    eval ans %%%count%%%
    * Wait random time then repeat it
    wait %random.5%
    say %ans%
  end
end
~

the clever bit: it uses the counter value itself as a variable name. set %c% %speech% expands to something like set 21 hello there, which stores "hello there" in variable %21%. then eval ans %%%count%%% does double-expansion to retrieve it.

tv implementation

#3001
TV Pull Knob~
1 c 2
pull~
* Command trigger on "pull tv"
if %cmd.mudcommand% == pull && pull /= tv
  * Toggle state using context variable
  if %is_on%
    eval is_on 0
    context is_on
    %send% %actor% You pull the knob. The television turns off with a click.
    %echoaround% %actor% %actor.name% turns off the television.
  else
    eval is_on 1
    context is_on
    %send% %actor% You pull the knob. The television flickers to life.
    %echoaround% %actor% %actor.name% turns on the television.
  end
else
  return 0
  halt
end
~
#3002
TV Turn Dial~
1 c 2
turn spin~
* Command trigger on "turn/spin tv"
if !%is_on%
  %send% %actor% The television is off.
  halt
end
* Cycle through channels 1-3
eval channel (%channel% %% 3) + 1
context channel
%send% %actor% You turn the dial. Now on channel %channel%.
%echoaround% %actor% %actor.name% changes the channel.
~
#3003
TV Broadcast~
1 f 100
~
* Random trigger - fires periodically
if !%is_on%
  halt
end
* Select message based on channel
if %channel% == 1
  switch %random.3%
    case 1
      set msg The weather is sunny.
    break
    case 2
      set msg Clouds rolling in.
    break
    case 3
      set msg Expect rain tonight.
    break
  done
else
  if %channel% == 2
    switch %random.3%
      case 1
        set msg Breaking news: mayor resigns!
      break
      case 2
        set msg Sports: home team wins!
      break
      case 3
        set msg Traffic is heavy downtown.
      break
    done
  else
    switch %random.3%
      case 1
        set msg Soap opera: dramatic pause...
      break
      case 2
        set msg Commercial: buy now!
      break
      case 3
        set msg Sitcom: laugh track plays.
      break
    done
  end
end
%echo% The television shows: %msg%
~

4. MUSHcode / Softcode

code stored in object attributes. $pattern:action creates commands. ^pattern:action creates listeners. @listen/@ahear for event reactions. %N = actor name, %0/%1 = captures.

real examples

basic command trigger:

&TURNON TV=$turn tv on:@emit %N turns on the TV.

echo device (monitor trigger):

@set EchoBox=MONITOR
&VA EchoBox=^* says, "*":@emit You hear an echo... %1 %1 %1...

listener reaction:

@listen Guard=*attacks*
@ahear Guard=@emit The guard steps in and shouts, "No fighting here!"

random selection:

&CMD-+CHECK Game=$+check *:@pemit %#=You rolled [rand(1,100)] on %0.

parrot implementation

@create Parrot
@set Parrot=MONITOR
@desc Parrot=A colorful tropical parrot. It watches you with intelligent eyes.

* Store memories as a space-separated list
&MEMORIES Parrot=

* Listen to all speech
&LISTEN Parrot=*
&AHEAR Parrot=@switch/first [strmatch(%0,*says*)]=1,{@va me=%0}

* Capture speech and store it
&VA Parrot=@switch/first [words(%q<1>)]>=[get(me/MAXMEM)]=1,{@trigger me/FORGET},{&MEMORIES me=[get(me/MEMORIES)] [after(%0,says)]};@trigger me/CHATTER

&MAXMEM Parrot=10

* Forget oldest memory when full
&FORGET Parrot=&MEMORIES me=[rest(get(me/MEMORIES))]

* Schedule random chatter
&CHATTER Parrot=@wait [rand(30,90)]=@switch [words(get(me/MEMORIES))]=0,,{@emit [name(me)] squawks: "[extract(get(me/MEMORIES),[rand(1,words(get(me/MEMORIES)))],1)]";@trigger me/CHATTER}

* Start chattering when created
@startup Parrot=@trigger me/CHATTER

tv implementation

@create Television
@desc Television=An old black-and-white television with a pull knob and a dial. The screen is [switch(get(me/ISON),1,glowing,dark)].

&ISON Television=0
&CHANNEL Television=1

* Channel content
&CH1 Television=The weather is sunny.|Clouds rolling in.|Expect rain tonight.
&CH2 Television=Breaking news: mayor resigns!|Sports: home team wins!|Traffic is heavy downtown.
&CH3 Television=Soap opera: dramatic pause...|Commercial: buy now!|Sitcom: laugh track plays.

* Pull command
&CMD-PULL Television=$pull television:@switch [get(me/ISON)]=1,{&ISON me=0;@oemit %#=%N turns off the television.;@pemit %#=You pull the knob. The television turns off with a click.},{&ISON me=1;@oemit %#=%N turns on the television.;@pemit %#=You pull the knob. The television flickers to life.;@trigger me/BROADCAST}

* Turn/spin dial command
&CMD-TURN Television=$turn television:@switch [get(me/ISON)]=0,{@pemit %#=The television is off.},{&CHANNEL me=[mod(add(get(me/CHANNEL),1),3)];@pemit %#=You turn the dial. Now on channel [get(me/CHANNEL)].;@oemit %#=%N changes the channel.}

&CMD-SPIN Television=$spin television:@trigger me/CMD-TURN

* Broadcast loop
&BROADCAST Television=@switch [get(me/ISON)]=0,,{@emit The television shows: [extract(get(me/CH[get(me/CHANNEL)]),[rand(1,3)],1,|)];@wait 15=@trigger me/BROADCAST}

* Start broadcasting if on
@startup Television=@switch [get(me/ISON)]=1,{@trigger me/BROADCAST}

5. MUF (Multi-User Forth)

stack-based language for TinyMUCK. : word ... ; defines words. me @ pushes current player. notify sends messages.

real examples

: hello-world
    me @ "Hello, world!" notify
;

: whoami
    me @
    "Your name is " me @ name strcat notify
;

: roll-die
    me @
    "You rolled a "
    random 6 % 1 +
    intostr strcat notify
;

parrot implementation sketch

$def MAXMEM 10

: parrot-remember ( str -- )
    me @ location contents  ( str loc-contents )
    begin
        dup while
        dup "parrot" stringpfx if
            dup "memories" array_getitem  ( str parrot memories )
            swap rot  ( memories parrot str )
            swap "memories" 3 pick  ( memories str "memories" parrot )
            3 pick array_appenditem  ( memories parrot )
            "memories" rot getpropstr  ( memories )
            array_count MAXMEM > if
                1 array_delitem  ( trim oldest )
            then
            "memories" swap setprop
        then
        next
    repeat
    pop pop
;

: parrot-chatter ( -- )
    me @ "memories" array_getitem  ( memories )
    dup array_count if
        random over array_count % 1 +  ( memories idx )
        array_getitem  ( phrase )
        me @ location
        "The parrot squawks: \"" 3 pick strcat "\"" strcat
        notify_except
    else
        pop
    then

    30 60 random + sleep
    parrot-chatter  ( recursive loop )
;

: parrot-listen
    begin
        read  ( str )
        dup "says" instr if
            parrot-remember
        else
            pop
        then
    repeat
;

(note: this is illustrative, not production-ready. MUF's event model would need more plumbing for real speech interception.)

6. DIL (DikuMUD Intermediate Language)

C-like compiled bytecode language. wait(SFB_*, condition) blocks for events. heartbeat for timers. labels + goto for loops. exec() runs game commands. self = attached object, activator = triggering player.

real examples

NPC that greets players:

dilbegin hi();
var
code
{
    :start:
    wait(SFB_DONE, command(CMD_AUTO_ENTER)
         and activator.type == UNIT_ST_PC);
    exec("say Hello, " + activator.name + "!", self);
    goto start;
}
dilend

guard daily routine with pathfinding:

dilbegin guardroutine(guardloc : string, dayguard : integer);
var
   sch : intlist;
code
{
   heartbeat := WAIT_SEC*5;
   :start:
   pause;
   if (mudhour == sch.[0])
   {
      exec("wake", self);
      exec("say Time to get going!", self);
      walkto(guardloc);
   }
   goto start;
}
dilend

speaking gem:

dilbegin gem_speak();
code
{
    heartbeat := 90 * PULSE_SEC;
    :start:
    wait(SFB_TICK, TRUE
         and self.outside.type == UNIT_ST_PC
         and self.equip);
    act("$1n says 'You look lovely today!'",
        A_ALWAYS, self.outside, self, null, TO_CHAR);
    goto start;
}
dilend

parrot implementation

dilbegin parrot();
var
    memories : stringlist;
    maxmem : integer;
    count : integer;
    phrase : string;
    u : unitptr;
code
{
    maxmem := 10;
    memories := {};
    heartbeat := PULSE_SEC * 5;

    :start:
    wait(SFB_COM, command("say") and activator.type == UNIT_ST_PC);

    * Capture what was said
    phrase := argument;
    if (length(phrase) > 0)
    {
        addstring(memories, phrase);
        count := length(memories);
        if (count > maxmem)
        {
            memories := delstr(memories, 0);
        }
    }

    goto chatter_wait;

    :chatter_wait:
    wait(SFB_TICK, TRUE);
    pause;
    if (rnd(1, 100) < 15 and length(memories) > 0)
    {
        goto chatter;
    }
    goto chatter_wait;

    :chatter:
    count := length(memories);
    if (count > 0)
    {
        phrase := memories.[rnd(0, count - 1)];
        exec("say " + phrase, self);
    }
    goto chatter_wait;
}
dilend

tv implementation

dilbegin television();
var
    is_on : integer;
    channel : integer;
    ch1 : stringlist;
    ch2 : stringlist;
    ch3 : stringlist;
    current : stringlist;
    msg : string;
code
{
    is_on := 0;
    channel := 1;

    ch1 := {"The weather is sunny.", "Clouds rolling in.", "Expect rain tonight."};
    ch2 := {"Breaking news: mayor resigns!", "Sports: home team wins!", "Traffic is heavy downtown."};
    ch3 := {"Soap opera: dramatic pause...", "Commercial: buy now!", "Sitcom: laugh track plays."};

    heartbeat := PULSE_SEC * 15;

    :start:
    wait(SFB_CMD, (command("pull") or command("turn") or command("spin"))
         and ("television" in argument or "tv" in argument));

    if (command("pull"))
    {
        if (is_on == 1)
        {
            is_on := 0;
            act("You pull the knob. The television turns off with a click.",
                A_ALWAYS, activator, self, null, TO_CHAR);
            act("$1n turns off the television.",
                A_ALWAYS, activator, self, null, TO_REST);
        }
        else
        {
            is_on := 1;
            act("You pull the knob. The television flickers to life.",
                A_ALWAYS, activator, self, null, TO_CHAR);
            act("$1n turns on the television.",
                A_ALWAYS, activator, self, null, TO_REST);
        }
    }

    if ((command("turn") or command("spin")) and is_on == 1)
    {
        channel := (channel % 3) + 1;
        act("You turn the dial. Now on channel " + itoa(channel) + ".",
            A_ALWAYS, activator, self, null, TO_CHAR);
        act("$1n changes the channel.",
            A_ALWAYS, activator, self, null, TO_REST);
    }

    goto broadcast_check;

    :broadcast_check:
    wait(SFB_TICK, TRUE);
    pause;
    if (is_on == 0)
    {
        goto start;
    }

    * Select current channel content
    if (channel == 1)
    {
        current := ch1;
    }
    else if (channel == 2)
    {
        current := ch2;
    }
    else
    {
        current := ch3;
    }

    msg := current.[rnd(0, length(current) - 1)];
    act("The television shows: " + msg,
        A_ALWAYS, self, null, null, TO_ALL);

    goto broadcast_check;
}
dilend

7. MobProg (Merc/ROM/SMAUG family)

inline scripts on mob definitions. trigger types: greet_prog, speech_prog, rand_prog, fight_prog, give_prog, etc. $n = actor, $i = self. if/else/endif conditionals.

real examples

wizard shop greeting:

>greet_prog 50~
if ispc($n)
  if rand(45)
    say How can I help you? Rings? Wands?
    grin
  else
    smile $n
    say Hello $n, what would you like today?
  endif
endif
~

random idle chatter:

>rand_prog 5~
if rand(51)
  say I know I put that bottle on the 53rd shelf.
  grumble
else
  grumble
  say Adventurers always bothering me.
endif
~

temple guardian (exit trigger):

>exit_prog 100~
if isgood $n
  say Hail!
  if carries $n holy
    mob transfer $n 2301
  else
    say Get a holy symbol first.
  endif
else
  curse $n
  say Get lost, scum!
endif
~

parrot implementation

>speech_prog 100~
* Store speech in mob's memory using mpvariable
* MobProgs don't have dynamic arrays, so we use a circular buffer
if ispc($n)
  if $speech != '!'
    * Increment counter
    if varcmp $i c == ''
      mpvariable c 1
    else
      mpvariable c $c + 1
    endif

    * Store in slot (mod 10)
    eval slot $c % 10
    mpvariable mem$slot $speech

    * Max stored
    if $c > 10
      mpvariable maxmem 10
    else
      mpvariable maxmem $c
    endif
  endif
endif
~

>rand_prog 10~
* Randomly repeat stored phrases
if rand(50)
  if varcmp $i maxmem > 0
    eval slot rnd($maxmem)
    eval phrase $mem$slot
    if $phrase != ''
      say $phrase
    endif
  endif
endif
~

(note: variable handling in MobProgs is implementation-specific. some versions have mpvariable, others don't support dynamic storage at all.)

8. CoffeeMUD Scripts

MobProg-inspired with 60+ event types and 80+ commands. also supports embedded JavaScript via <SCRIPT> blocks.

real examples

trader NPC:

GREET_PROG 75
say Welcome $n! I am a strange trader!
~

FIGHT_PROG 99
IF RAND(15)
    say Think yer TOUGH eh?
ELSE
    IF RAND(15)
        say Take THAT!
    ENDIF
ENDIF
~

GIVE_PROG all
IF GOLDAMT($o < 100)
    say You can do better than THAT.
    drop $o
ELSE
    say THAT's what I LIKE!
    MPOLOAD a nice tunic
    give "a nice tunic" "$n"
ENDIF
~

speech-reactive NPC:

SPEECH_PROG weapon sword mace
IF WORN($n sword)
    say You are wielding a sword!
ELSE
    IF HAS($n sword)
        say You have a sword!
    ENDIF
ENDIF
~

embedded JavaScript:

GREET_PROG 100
<SCRIPT>
    if(ISPC("$n"))
    {
        MPECHO("The ground shakes!");
    }
</SCRIPT>
~

parrot implementation (pure CoffeeMUD scripting)

SPEECH_PROG *
IF ISPC($n)
    IF !STRCONTAINS($t !)
        MPSETVAR $i mem_count $<$i.mem_count>+1
        MPSETVAR $i mem_$<$i.mem_count> $t
        IF $<$i.mem_count> > 10
            MPSETVAR $i mem_count 10
        ENDIF
    ENDIF
ENDIF
~

RAND_PROG 10
IF RAND(50)
    IF $<$i.mem_count> > 0
        MPSETVAR I slot RAND(1 $<$i.mem_count>)
        say $<$i.mem_$<I.slot>>
    ENDIF
ENDIF
~

tv implementation (JavaScript hybrid)

LOAD_PROG 100
<SCRIPT>
    MPSETVAR("$i", "is_on", "0");
    MPSETVAR("$i", "channel", "1");
    MPSETVAR("$i", "ch1_1", "The weather is sunny.");
    MPSETVAR("$i", "ch1_2", "Clouds rolling in.");
    MPSETVAR("$i", "ch1_3", "Expect rain tonight.");
    MPSETVAR("$i", "ch2_1", "Breaking news: mayor resigns!");
    MPSETVAR("$i", "ch2_2", "Sports: home team wins!");
    MPSETVAR("$i", "ch2_3", "Traffic is heavy downtown.");
    MPSETVAR("$i", "ch3_1", "Soap opera: dramatic pause...");
    MPSETVAR("$i", "ch3_2", "Commercial: buy now!");
    MPSETVAR("$i", "ch3_3", "Sitcom: laugh track plays.");
</SCRIPT>
~

FUNCTION_PROG pull_trigger
IF $<$i.is_on> == 1
    MPSETVAR $i is_on 0
    MPECHO $n turns off the television.
    TELL $n You pull the knob. The television turns off with a click.
ELSE
    MPSETVAR $i is_on 1
    MPECHO $n turns on the television.
    TELL $n You pull the knob. The television flickers to life.
ENDIF
~

FUNCTION_PROG turn_trigger
IF $<$i.is_on> == 0
    TELL $n The television is off.
ELSE
    MPSETVAR $i channel ($<$i.channel> % 3) + 1
    TELL $n You turn the dial. Now on channel $<$i.channel>.
    MPECHO $n changes the channel.
ENDIF
~

RAND_PROG 20
IF $<$i.is_on> == 1
    <SCRIPT>
        var ch = GSTAT("$i", "channel");
        var idx = RAND(1, 3);
        var msg = GSTAT("$i", "ch" + ch + "_" + idx);
        MPECHO("The television shows: " + msg);
    </SCRIPT>
ENDIF
~

9. room.js (JavaScript MOO)

Node.js MOO-like system. verbs are .js files on the filesystem per object. dispatch signature: ({ player, dobj, iobj, verbstr, argstr, dobjstr, prepstr, iobjstr }). run.in() for timers.

real examples

guitar with song playback:

function play({ player }) {
  if (this.location !== player) {
    player.tell("You don't have that.");
    return;
  }
  this.stropheIndex = 1;
  this.playing = player;
  this.playEmote();
}

function playStrophe() {
  const song = this.song.trim().split(/\n\n/);
  let strophe = song[this.stropheIndex - 1];
  this.playing.location.announce(() => strophe, this.playing);
  this.stropheIndex++;
  if (this.stropheIndex > song.length) {
    this.stropheIndex = 0;
    this.playing = null;
    return;
  }
  run.in(this.id + '.playStrophe()', 4000);
}

mouse that flees on examine:

function onExamine(player) {
  player.tell(`The ${this.name} starts panicking!`);
  const exitDirs = Object.keys(this.location.exits);
  if (exitDirs.length === 0) return;
  const picked = exitDirs[Math.floor(Math.random() * exitDirs.length)];
  this.location.goDirection({ player: this, argstr: picked });
}

parrot implementation

// parrot.js
function onCreate() {
  this.memories = [];
  this.maxMemories = 10;
  this.chatting = false;
}

function onHear({ speaker, message }) {
  // listen to other people's speech
  if (speaker === this) return;
  if (message.length === 0) return;

  this.memories.push(message);
  if (this.memories.length > this.maxMemories) {
    this.memories.shift();
  }

  if (!this.chatting) {
    this.startChattering();
  }
}

function startChattering() {
  this.chatting = true;
  this.chatter();
}

function chatter() {
  if (!this.location) {
    this.chatting = false;
    return;
  }

  if (this.memories.length > 0) {
    const phrase = this.memories[Math.floor(Math.random() * this.memories.length)];
    this.location.announce(() => `${this.name} squawks: "${phrase}"`);
  }

  const delay = 30000 + Math.random() * 60000; // 30-90 seconds
  run.in(`${this.id}.chatter()`, delay);
}

function onMove() {
  // restart chattering in new location
  if (this.chatting && this.location) {
    this.chatter();
  }
}

module.exports = {
  onCreate,
  onHear,
  startChattering,
  chatter,
  onMove
};

tv implementation

// television.js
function onCreate() {
  this.isOn = false;
  this.channel = 1;
  this.channels = [
    ["The weather is sunny.", "Clouds rolling in.", "Expect rain tonight."],
    ["Breaking news: mayor resigns!", "Sports: home team wins!", "Traffic is heavy downtown."],
    ["Soap opera: dramatic pause...", "Commercial: buy now!", "Sitcom: laugh track plays."]
  ];
  this.broadcasting = false;
}

function pull({ player }) {
  if (this.isOn) {
    this.isOn = false;
    this.broadcasting = false;
    player.tell("You pull the knob. The television turns off with a click.");
    this.location.announce(() => `${player.name} turns off the television.`, player);
  } else {
    this.isOn = true;
    player.tell("You pull the knob. The television flickers to life.");
    this.location.announce(() => `${player.name} turns on the television.`, player);
    this.startBroadcast();
  }
}

function turn({ player }) {
  if (!this.isOn) {
    player.tell("The television is off.");
    return;
  }
  this.channel = (this.channel % this.channels.length) + 1;
  player.tell(`You turn the dial. Now on channel ${this.channel}.`);
  this.location.announce(() => `${player.name} changes the channel.`, player);
}

function spin({ player }) {
  this.turn({ player });
}

function startBroadcast() {
  if (this.broadcasting || !this.isOn) return;
  this.broadcasting = true;
  this.broadcast();
}

function broadcast() {
  if (!this.isOn || !this.location) {
    this.broadcasting = false;
    return;
  }

  const msgs = this.channels[this.channel - 1];
  const msg = msgs[Math.floor(Math.random() * msgs.length)];
  this.location.announce(() => `The television shows: ${msg}`);

  run.in(`${this.id}.broadcast()`, 15000);
}

function onMove() {
  this.broadcasting = false;
  if (this.isOn && this.location) {
    this.startBroadcast();
  }
}

module.exports = {
  onCreate,
  pull,
  turn,
  spin,
  startBroadcast,
  broadcast,
  onMove
};

10. Ranvier (YAML + JavaScript)

data-driven: entities defined in YAML, behaviors in JS modules. events connect them.

real examples

NPC definition:

- id: 2
  name: "Rat"
  keywords: ["rat"]
  description: "A fat rat scurries about."
  script: "1-rat"
  items: ["limbo:sliceofcheese"]
  quests: ["limbo:onecheeseplease"]
  attributes:
    health: 100
  damage: "1-7"
  behaviors:
    lootable:
      table:
        pools:
          - "limbo:junk"

script (unique per-NPC):

module.exports = {
  listeners: {
    playerEnter: state => function(player) {
      this.emit('combat', player);
    }
  }
};

parrot implementation

# areas/town/npcs.yml
- id: parrot
  name: "colorful parrot"
  keywords: ["parrot", "bird"]
  description: "A bright tropical parrot with green and red plumage. It watches you with intelligent eyes."
  script: "town-parrot"
  behaviors:
    parrot-mimic:
      maxMemories: 10

// behaviors/npc/parrot-mimic.js
module.exports = {
  listeners: {
    spawn: state => function() {
      this.memories = [];
      this.maxMemories = this.getBehavior('parrot-mimic').maxMemories || 10;
      this.startChattering();
    },

    playerSay: state => function(player, message) {
      if (message.length === 0) return;

      this.memories.push(message);
      if (this.memories.length > this.maxMemories) {
        this.memories.shift();
      }
    }
  }
};

// Add to NPC prototype
NPC.prototype.startChattering = function() {
  const chatter = () => {
    if (!this.room || this.memories.length === 0) {
      setTimeout(chatter, 30000 + Math.random() * 60000);
      return;
    }

    const phrase = this.memories[Math.floor(Math.random() * this.memories.length)];
    B.sayAt(this.room, `${this.name} squawks: "${phrase}"`);

    setTimeout(chatter, 30000 + Math.random() * 60000);
  };

  chatter();
};

tv implementation

# areas/town/items.yml
- id: television
  name: "vintage television"
  keywords: ["television", "tv"]
  description: "An old black-and-white television with a pull knob and a dial."
  script: "town-television"
  behaviors:
    tv-broadcast:
      channels:
        - ["The weather is sunny.", "Clouds rolling in.", "Expect rain tonight."]
        - ["Breaking news: mayor resigns!", "Sports: home team wins!", "Traffic is heavy downtown."]
        - ["Soap opera: dramatic pause...", "Commercial: buy now!", "Sitcom: laugh track plays."]
  metadata:
    isOn: false
    channel: 0

// commands/pull.js
module.exports = {
  usage: 'pull <item>',
  command: state => (args, player) => {
    const item = state.ItemManager.parseDot(args, player.room.items);
    if (!item) {
      return B.sayAt(player, "Pull what?");
    }

    if (item.hasKeyword('television')) {
      const isOn = item.getMeta('isOn') || false;
      if (isOn) {
        item.setMeta('isOn', false);
        B.sayAt(player, "You pull the knob. The television turns off with a click.");
        B.sayAtExcept(player.room, `${player.name} turns off the television.`, player);
      } else {
        item.setMeta('isOn', true);
        B.sayAt(player, "You pull the knob. The television flickers to life.");
        B.sayAtExcept(player.room, `${player.name} turns on the television.`, player);
        item.emit('startBroadcast');
      }
    }
  }
};

// commands/turn.js
module.exports = {
  aliases: ['spin'],
  usage: 'turn <item>',
  command: state => (args, player) => {
    const item = state.ItemManager.parseDot(args, player.room.items);
    if (!item) {
      return B.sayAt(player, "Turn what?");
    }

    if (item.hasKeyword('television')) {
      if (!item.getMeta('isOn')) {
        return B.sayAt(player, "The television is off.");
      }

      const behavior = item.getBehavior('tv-broadcast');
      const numChannels = behavior.channels.length;
      const currentChannel = item.getMeta('channel') || 0;
      const newChannel = (currentChannel + 1) % numChannels;
      item.setMeta('channel', newChannel);

      B.sayAt(player, `You turn the dial. Now on channel ${newChannel + 1}.`);
      B.sayAtExcept(player.room, `${player.name} changes the channel.`, player);
    }
  }
};

// behaviors/item/tv-broadcast.js
module.exports = {
  listeners: {
    spawn: state => function() {
      if (this.getMeta('isOn')) {
        this.startBroadcast();
      }
    },

    startBroadcast: state => function() {
      const broadcast = () => {
        if (!this.getMeta('isOn') || !this.room) {
          return;
        }

        const behavior = this.getBehavior('tv-broadcast');
        const channel = this.getMeta('channel') || 0;
        const messages = behavior.channels[channel];
        const msg = messages[Math.floor(Math.random() * messages.length)];

        B.sayAt(this.room, `The television shows: ${msg}`);

        setTimeout(broadcast, 15000);
      };

      broadcast();
    }
  }
};

11. Evennia (Python Typeclasses)

Python classes with persistence hooks. at_object_creation() runs once. db.* persists. Scripts for timed behavior.

real examples

NPC reacting to player entry:

class NPC(Character):
    def at_char_entered(self, character, **kwargs):
        if self.db.is_aggressive:
            self.execute_cmd(f"say Graaah! Die, {character}!")
        else:
            self.execute_cmd(f"say Greetings, {character}!")

room that notifies NPCs:

class Room(DefaultRoom):
    def at_object_receive(self, arriving_obj, source_location, **kwargs):
        if arriving_obj.account:
            for item in self.contents:
                if utils.inherits_from(item, "typeclasses.npcs.NPC"):
                    item.at_char_entered(arriving_obj, **kwargs)

parrot implementation

from evennia import DefaultCharacter
from evennia.utils import delay
import random

class Parrot(DefaultCharacter):
    """
    A parrot that listens to speech and randomly repeats it.
    """

    def at_object_creation(self):
        """Called once when object is first created."""
        super().at_object_creation()
        self.db.memories = []
        self.db.max_memories = 10
        self.db.chatty = True

    def at_object_receive(self, obj, source_location, **kwargs):
        """Called when moved to a new location."""
        super().at_object_receive(obj, source_location, **kwargs)
        if self.db.chatty:
            self.start_chattering()

    def hear_speech(self, speaker, message):
        """
        Called by room when someone speaks.
        Hook this into your room's msg() or create a custom at_say hook.
        """
        if speaker == self:
            return

        if message and len(message) > 0:
            self.db.memories.append(message)
            if len(self.db.memories) > self.db.max_memories:
                self.db.memories.pop(0)

    def chatter(self):
        """Randomly repeat something heard."""
        if not self.location:
            return

        if self.db.memories:
            phrase = random.choice(self.db.memories)
            self.location.msg_contents(
                f'{self.get_display_name(looker=None)} squawks: "{phrase}"'
            )

        if self.db.chatty:
            delay(random.randint(30, 90), self.chatter)

    def start_chattering(self):
        """Begin the chatter loop."""
        if self.db.chatty:
            delay(random.randint(30, 90), self.chatter)

to integrate speech capturing, add to your Room typeclass:

from evennia import DefaultRoom

class Room(DefaultRoom):
    def at_say(self, speaker, message, **kwargs):
        """Hook called when someone speaks in the room."""
        # notify all parrot-like objects
        for obj in self.contents:
            if hasattr(obj, 'hear_speech'):
                obj.hear_speech(speaker, message)

tv implementation

from evennia import DefaultObject
from evennia.utils import delay
import random

class Television(DefaultObject):
    """
    An interactive TV with pull knob and turn dial.
    """

    def at_object_creation(self):
        """Called once when object is first created."""
        super().at_object_creation()
        self.db.is_on = False
        self.db.channel = 1
        self.db.channels = {
            1: ["The weather is sunny.", "Clouds rolling in.", "Expect rain tonight."],
            2: ["Breaking news: mayor resigns!", "Sports: home team wins!", "Traffic is heavy downtown."],
            3: ["Soap opera: dramatic pause...", "Commercial: buy now!", "Sitcom: laugh track plays."]
        }
        self.db.broadcasting = False

        # add commands to the object
        self.cmdset.add_default(TvCmdSet, persistent=True)

    def get_display_name(self, looker=None, **kwargs):
        """Add power state to name."""
        name = super().get_display_name(looker, **kwargs)
        if self.db.is_on:
            return f"{name} (glowing)"
        return f"{name} (dark)"

    def start_broadcast(self):
        """Begin broadcasting loop."""
        if self.db.broadcasting or not self.db.is_on:
            return
        self.db.broadcasting = True
        self.broadcast()

    def broadcast(self):
        """Show a message from current channel."""
        if not self.db.is_on or not self.location:
            self.db.broadcasting = False
            return

        messages = self.db.channels.get(self.db.channel, [])
        if messages:
            msg = random.choice(messages)
            self.location.msg_contents(f"The television shows: {msg}")

        delay(15, self.broadcast)

    def at_object_receive(self, obj, source_location, **kwargs):
        """When moved to new location."""
        super().at_object_receive(obj, source_location, **kwargs)
        self.db.broadcasting = False
        if self.db.is_on and self.location:
            self.start_broadcast()


from evennia import CmdSet, Command

class CmdPull(Command):
    """
    Pull the TV knob to toggle power.

    Usage:
        pull television
    """
    key = "pull"

    def func(self):
        tv = self.obj
        if tv.db.is_on:
            tv.db.is_on = False
            tv.db.broadcasting = False
            self.caller.msg("You pull the knob. The television turns off with a click.")
            self.caller.location.msg_contents(
                f"{self.caller.name} turns off the television.",
                exclude=self.caller
            )
        else:
            tv.db.is_on = True
            self.caller.msg("You pull the knob. The television flickers to life.")
            self.caller.location.msg_contents(
                f"{self.caller.name} turns on the television.",
                exclude=self.caller
            )
            tv.start_broadcast()


class CmdTurn(Command):
    """
    Turn the TV dial to change channels.

    Usage:
        turn television
        spin television
    """
    key = "turn"
    aliases = ["spin"]

    def func(self):
        tv = self.obj
        if not tv.db.is_on:
            self.caller.msg("The television is off.")
            return

        num_channels = len(tv.db.channels)
        tv.db.channel = (tv.db.channel % num_channels) + 1
        self.caller.msg(f"You turn the dial. Now on channel {tv.db.channel}.")
        self.caller.location.msg_contents(
            f"{self.caller.name} changes the channel.",
            exclude=self.caller
        )


class TvCmdSet(CmdSet):
    """Commands available on the TV object."""

    def at_cmdset_creation(self):
        self.add(CmdPull())
        self.add(CmdTurn())

patterns across languages

after looking at all these systems, some common patterns emerge:

event-driven architecture: almost every DSL is fundamentally event-driven. greet/speech/command/timer triggers dominate. even the procedural-looking ones (LPC, DIL) use wait() and callbacks.

state storage:

prototype systems (MOO, room.js) use object properties directly
file-based systems (LPC) use member variables
limited systems (DG Scripts, MobProg) get creative with numbered variables or simple flags
modern systems (Evennia) use persistent db.* attributes

timer patterns:

fork + recursion (MOO)
call_out (LPC)
wait + goto (DIL)
RAND_PROG percentage (MobProg)
setTimeout / delay (JavaScript / Python)

command dispatch:

verb matching (MOO, room.js)
add_action (LPC)
command triggers (DG Scripts, CoffeeMUD)
$pattern (MUSHcode)
typeclass methods (Evennia)

variable substitution: older systems love %actor%, $n, @me style placeholders. newer ones prefer real language variables.

embedded vs external: some systems inline scripts into data files (MobProg, DG Scripts), others separate code from data (LPC, Ranvier). the hybrid approach (YAML data + JS behaviors) seems to win for maintainability.

complexity gradient:

simple: MobProg, DG Scripts (limited control flow, mainly if/else)
medium: MOO, MUSHcode (more features but still constrained)
full language: LPC, DIL, JavaScript, Python (you can do anything)

the parrot problem: most systems can handle it, but the approaches differ:

dynamic lists: MOO, LPC, JavaScript, Python do it naturally
fixed-size buffers: DG Scripts use numbered globals, very clever
impossible: basic MobProg can't really do it without extensions

the tv problem: tests both state management and command handling. simpler systems struggle with the two-verb interaction (pull vs turn), while OOP systems handle it easily.

inspiration for our DSL:

lean toward event-driven, not polling
make state storage first-class (not a hack)
support both inline scripts (for simple stuff) and external modules (for complex behaviors)
variable substitution is nice for builders, real variables for power users
timer/delay primitives are essential
speech/emote/action hooks should be easy

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MUD Scripting Languages Reference

1. MOO Verb Language

real examples

parrot implementation

tv implementation

2. LPC (LPMud)

real examples

parrot implementation

tv implementation

3. DG Scripts (CircleMUD/TBAmud)

real examples

parrot implementation

tv implementation

4. MUSHcode / Softcode

real examples

parrot implementation

tv implementation

5. MUF (Multi-User Forth)

real examples

parrot implementation sketch

6. DIL (DikuMUD Intermediate Language)

real examples

parrot implementation

tv implementation

7. MobProg (Merc/ROM/SMAUG family)

real examples

parrot implementation

8. CoffeeMUD Scripts

real examples

parrot implementation (pure CoffeeMUD scripting)

tv implementation (JavaScript hybrid)

9. room.js (JavaScript MOO)

real examples

parrot implementation

tv implementation

10. Ranvier (YAML + JavaScript)

real examples

parrot implementation

tv implementation

11. Evennia (Python Typeclasses)

real examples

parrot implementation

tv implementation

patterns across languages

47 KiB

Raw Blame History