Created
June 12, 2015 15:17
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system-composition in clojure
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(ns composition.core | |
(:require [com.stuartsierra.dependency :as dep])) | |
#_(defprotocol Component ; an interesting thought | |
(dependencies [component]) | |
(constructor [component configuration])) | |
(defn using [dependencies constructor] | |
{::dependencies dependencies | |
::constructor constructor}) | |
(defn dependencies [component] | |
(::dependencies component)) | |
(defn instantiate [component system] | |
(->> (::dependencies component) | |
(map (partial get system)) | |
(apply (::constructor component)))) | |
(defn dependency-graph [system-map] | |
(reduce-kv | |
(fn [g k v] | |
(reduce | |
(fn [g d] (dep/depend g k d)) | |
g | |
(dependencies v))) | |
(dep/graph) | |
system-map)) | |
(defn compose [system-map] | |
(->> system-map | |
dependency-graph | |
dep/topo-sort | |
(reduce | |
(fn [system component-id] | |
(assoc system component-id (instantiate (system-map component-id) system))) | |
{}))) | |
(defmacro component [dependencies & body] | |
`(using ~(mapv keyword dependencies) | |
(fn ~dependencies (do ~@body)))) | |
(defmacro defcomponent [name dependencies & body] | |
`(def ~name (component ~dependencies ~@body))) | |
(defn singleton [value] | |
(using [] (constantly value))) | |
(defn create-sneer-admin [network tuple-space] | |
{:type :admin :network network :tuple-space tuple-space}) | |
(defcomponent tuple-space [tuple-base] | |
{:type :ts :tuple-base tuple-base}) | |
(defcomponent tuple-base [db network] | |
{:type :tb :db db :network network}) | |
; main | |
(compose {:sneer-admin (using [:network :tuple-space] create-sneer-admin) | |
:network (singleton :the-network) | |
:db (singleton :the-db) | |
:tuple-base tuple-base | |
:tuple-space tuple-space}) |
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