# LambdaMOO!

### What's a LambdaMOO?

That's a difficult question. We recommend visiting some place like www.moo.mud.org to find out more about LambdaMOO, and muds and moos in general, but we'll include a brief description below to get you started.

LambdaMOO, founded in 1990 by Pavel Curtis at Xerox PARC, is one of the oldest continuously-operating MUDs, a class of online worlds with roots in text-based multiplayer role-playing games. MUDs (multi-user dungeons) differ from most chat and gaming systems in their use of a persistent representation of a virtual world, often created by the participants, who are represented as characters of their own choosing. The mechanisms of social interaction in MUDs are designed to reinforce the illusion that the user is present in the virtual space. LambdaMOO is a MOO: a MUD that uses an object-oriented programming language to manipulate objects in the virtual world.

LambdaMOO appears as a series of interconnected rooms (modeled as a mansion), populated by users and objects who may move from room to room. Each room provides a chat channel shared by just those users in the room (users can also communicate privately), and typically has an elaborate text description that imbues it with its own look and feel.'' In addition to speech, users express themselves via a large collection of {\em emotes,\/} allowing a rich set of simulated actions, and the expression of emotional states:

1. Buster is overwhelmed by all these paper deadlines.
2. Buster begins to slowly tear his hair out, one strand at a time.
3. HFh comforts Buster.
4. HFh [to Buster]: Remember, the mighty oak was once a nut like you.
5. Buster [to HFh]: Right, but his personal growth was assured. Thanks anyway, though.
6. Buster feels better now.

Lines (1) and (2) are initiated by emote commands by user Buster, expressing his emotional state, while (3) and (4) are examples of emote and speech acts, respectively, by HFh. Lines (5) and (6) are speech and emote by Buster. Though there are many standard emotes, such as the use of comfort in line (3) above, the variety is essentially unlimited, as players have the ability to create their own emotes.

The rooms and objects in LambdaMOO are created by users themselves, who devise descriptions, and control access by other users. Users can also create objects with methods (or verbs) that can be invoked by other players. In fact everything in LambdaMOO is an object, and every event is the invocation of a verb on some object, including speech (usually invocations of the tell verb).

LambdaMOO is thus a long-standing, ongoing experiment in collective programming and creation, with often stunning results that can only be fully appreciated firsthand. Inventions include technical objects, such as the lag meter, which provides recent statistics on server load; objects serving a mix of practical and metaphorical purposes, such as elevators that move users between floors; objects with social uses, such as the birthday meter, where users register their birthdays publicly; and objects that just entertain or annoy, such as the Cockatoo, a virtual bird who occasionally repeats an utterance recently overheard. There is also a long history of objects that can be viewed as experiments in AI.