---

1 What is Goblins?

Goblins is a distributed object programming environment. Features:

• Quasi-functional object system: users hold on to references of objects/actors, but objects/actors are just procedures. Rather than directly mutating, objects/actors can specify that they should “become” a new version of themselves when they handle the next invocation.
• Fully distributed, networked, secure p2p communication: via OCapN, the Object Capability Network (which features CapTP, the Capability Transport Protocol), you can communicate with other objects over a network connection. Distributed object interactions are safe because of ocap security guarantees.
• Transactional updates: changes happen within a transaction. If an unhandled exception occurs, Goblins can “roll back” history as if the message never happened, avoiding confused state changes throughout the system.
• Time travel: you can snapshot old revisions of the system and interact with them.
• Asynchronous programming with sophisticated promise chaining: asynchronous message passing with promises is supported. Promises work such that there’s no need to wait for promises to resolve before interacting… you can communicate with the future that doesn’t even yet exist! Sent a message to that remote car factory asking for a new car? Why wait for the car to be delivered… you can send it a drive message at the same time, and both messages can be delivered across the network in a single hop.
• Communicating event loops: objects across multiple event loops (aka “vats”) can communicate, whether in the same OS process or across the network.
• Synchronous and asynchronous behavior, integrated but distinguished: both synchronous and asynchronous programming is supported, but only objects in the same “vat” (event loop) can perform synchronous immediate calls. All objects can perform asynchronous calls against each other.
• A library, not a language: Goblins is itself a library that can be utilized across a wide variety of Guile programs.
• Object capability security: Goblins itself is built for object capability (OCap) security, which is to say that you can only operate on the references you have access to. Goblins embraces and builds upon this foundation. (However, full OCap security will require utilizing the sandboxing features of Guile; demonstrations of this coming soon.)

Goblins’ design is inspired by the E programming language and by the observation that lambda is already the ultimate security mechanism (ie, normal argument-passing in programs, if taken seriously/purely, is already all the security system needed).

Spritely Networked Communities Institute was created to advance decentralized networking infrastructure, particularly as it pertains to social networks. Goblins is the heart of the system, on which other layers are built. At the time of writing, two key versions of Goblins are supported, the Racket version of Goblins, and the Guile version. This manual is for the Guile edition of Spritely Goblins.