---

name: bassline description: Work with Bassline: a programming environment for reflexive distributed systems. Use Bassline when you want to make p2p connections with a simple API, build propagation networks, use a TCL with state serialization or manage agents in distributed settings. license: AGPL-3.0 compatibility: Requires @bassline packages installed in the project

Bassline

Everything in Bassline is a resource with two operations:

Copyawait resource.get(headers) // → { headers, body }
await resource.put(headers, body) // → { headers, body }

Semantic Addressing

Everything in Bassline is semantically addressed. Resources don't have a single concrete identity—instead they exist relative to other resources.

Routers are resources that delegate interactions by dispatching based on information in the headers. Paths are just a common example of semantic routing information. This lets us talk about resources as though we were interacting with a file-system.

Copy// Read a value - the path describes what we want, not where it lives
const result = await resource.get({ path: '/cells/counter/value' })
// { headers: { type: '/types/cell-value' }, body: 42 }

// Write a value
const result = await resource.put({ path: '/store/users/alice' }, { name: 'Alice' })
// { headers: {}, body: { name: 'Alice' } }

Paths route segment by segment:

• /cells/counter/value → cells → counter → value
• /store/users/alice → store → users → alice

You are free to choose whatever dispatch logic makes sense in your domain.

Response Format

Every operation returns { headers, body }:

Copy// Success
{ headers: {}, body: { name: 'Alice' } }
{ headers: { type: '/types/cell' }, body: { lattice: 'maxNumber', value: 5 } }

// Errors - check headers.condition
{ headers: { condition: 'not-found' }, body: null }
{ headers: { condition: 'error', message: 'Something went wrong' }, body: null }

Always check for conditions:

Copyconst result = await kit.get({ path: '/cells/counter/value' })

if (result.headers.condition === 'not-found') {
  // Resource doesn't exist
}
if (result.headers.condition === 'error') {
  console.error(result.headers.message)
}

The Kit Rule

A kit is simply a resource passed via headers.

When a resource needs flexible or dynamic access to other resources that it doesn't know about ahead of time, it can do so with a kit. This makes kits a form of dependency injection for resources.

Copyconst worker = resource({
  put: async (h, task) => {
    // Access resources via kit - we don't know where they live
    const { body: config } = await h.kit.get({ path: '/config' })

    // Write results via kit
    await h.kit.put({ path: '/results/latest' }, result)

    return { headers: {}, body: { done: true } }
  },
})

When a resource delegates to another resource, it can provide an alternative kit to change the effective "world" a resource is interacting in. Same resource, different kit = different capabilities.

Because resources don't have concrete identities, kits can work over network boundaries. When interacting with a kit that is located on an external machine, we can simply proxy interactions through another local resource we create.

Creating Resources

Basic Resource

Copyimport { resource } from '@bassline/core'

let count = 0

const counter = resource({
  get: async h => ({ headers: {}, body: count }),
  put: async (h, b) => {
    count = b
    return { headers: {}, body: count }
  },
})

Routing by Path

Copyimport { routes } from '@bassline/core'

const app = routes({
  cells: cellsResource,
  store: storeResource,
  fn: fnResource,
  unknown: fallbackResource, // catches unmatched paths
})

Capturing Path Parameters

Copyimport { bind } from '@bassline/core'

// Captures segment into h.params.id
const users = bind(
  'id',
  resource({
    get: async h => {
      const userId = h.params.id // 'alice' from '/alice/profile'
      // ...
    },
  })
)

Quick Reference

Packages

Bassline is split into focused packages. See the reference files for detailed usage:

When to Use Each

• Building state that merges → cells with lattices (core.md)
• Storing key/value data → store (core.md)
• Reactive computation → propagators (core.md)
• Persisting an application → blits (blit.md)
• Writing boot/init scripts → TCL (tcl.md)
• Direct SQL access → database (database.md)
• LLM-powered features → services (services.md)
• Peer trust/capabilities → trust (trust.md)