cljam-integrant

Data-driven system composition for cljam. A port of Integrant.

Define your system as a data map. Integrant resolves dependencies, starts components in topological order, and stops them in reverse. All lifecycle operations are async.

Installation

npm install @regibyte/cljam-integrant

import { library as integrantLib } from '@regibyte/cljam-integrant'

const session = createSession({ ...nodePreset(), libraries: [integrantLib] })

Usage

(require '[cljam.integrant.core :as ig])

;; 1. Define the config map
(def config
  {:app/db     {:url "postgresql://localhost/mydb"}
   :app/server {:port 3000 :db (ig/ref :app/db)}})

;; 2. Implement lifecycle multimethods
(defmethod ig/init-key :app/db [_ {:keys [url]}]
  (connect! url))

(defmethod ig/halt-key! :app/db [_ db]
  (disconnect! db))

(defmethod ig/init-key :app/server [_ {:keys [port db]}]
  (start-server! port db))

(defmethod ig/halt-key! :app/server [_ server]
  (stop-server! server))

;; 3. Start and stop
(def *system (atom nil))

(async (reset! *system @(ig/init config)))
(async @(ig/halt! @*system))

Partial start

;; Start only :app/db and its declared dependencies
(ig/init config #{:app/db})

Hot reload

(async
  @(ig/suspend! @*system)
  ;; ... reload code / new config here ...
  (reset! *system @(ig/resume new-config @*system)))

Override resume-key to reuse unchanged components:

(defmethod ig/resume-key :app/db [key value old-value old-impl]
  (if (= value old-value)
    old-impl           ;; config unchanged — reuse
    @(ig/init-key key value)))

API

References

Form	Description
(ig/ref key)	Dependency on key — resolved to started component during init
(ig/refset key)	Like ref, but collects all matching keys into a set
(ig/ref? x)	True if x is a ref

Lifecycle multimethods

Multimethod	Signature
init-key	(key value) → component
halt-key!	(key component) → nil
suspend-key!	(key component) → nil (default: calls halt-key!)
resume-key	(key value old-value old-impl) → component (default: calls init-key)

System operations (all return CljPending)

Function	Description
(ig/init config)	Start all components
(ig/init config keys)	Start only the given keys
(ig/halt! system)	Stop all components in reverse order
(ig/suspend! system)	Suspend for hot reload
(ig/resume config system)	Restart, reusing unchanged components