├── .gitignore ├── CHANGELOG.md ├── LICENSE ├── README.md ├── doc └── intro.md ├── project.clj ├── src └── com │ └── hypirion │ └── conduit.clj └── test └── com └── hypirion └── conduit_test.clj /.gitignore: -------------------------------------------------------------------------------- 1 | /target 2 | /classes 3 | /checkouts 4 | pom.xml 5 | pom.xml.asc 6 | *.jar 7 | *.class 8 | /.lein-* 9 | /.nrepl-port 10 | .hgignore 11 | .hg/ 12 | -------------------------------------------------------------------------------- /CHANGELOG.md: -------------------------------------------------------------------------------- 1 | # Change Log 2 | All notable changes to this project will be documented in this file. This change log follows the conventions of [keepachangelog.com](http://keepachangelog.com/). 3 | 4 | ## [Unreleased] 5 | ### Changed 6 | - Add a new arity to `make-widget-async` to provide a different widget shape. 7 | 8 | ## [0.1.1] - 2016-05-28 9 | ### Changed 10 | - Documentation on how to make the widgets. 11 | 12 | ### Removed 13 | - `make-widget-sync` - we're all async, all the time. 14 | 15 | ### Fixed 16 | - Fixed widget maker to keep working when daylight savings switches over. 17 | 18 | ## 0.1.0 - 2016-05-28 19 | ### Added 20 | - Files from the new template. 21 | - Widget maker public API - `make-widget-sync`. 22 | 23 | [Unreleased]: https://github.com/your-name/clj-conduit/compare/0.1.1...HEAD 24 | [0.1.1]: https://github.com/your-name/clj-conduit/compare/0.1.0...0.1.1 25 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | THE ACCOMPANYING PROGRAM IS PROVIDED UNDER THE TERMS OF THIS ECLIPSE PUBLIC 2 | LICENSE ("AGREEMENT"). 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No party to this 212 | Agreement will bring a legal action under this Agreement more than one year 213 | after the cause of action arose. Each party waives its rights to a jury trial 214 | in any resulting litigation. 215 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # clj-conduit 2 | 3 | Conduits are transducers with a new interface. It tries to be simpler and more 4 | readable than the raw transducer interface, at the cost of performance. 5 | 6 | With conduits, the `take` transducer can be implemented as follows: 7 | 8 | ```clj 9 | (ns my.lib 10 | (:refer-clojure :exclude [await]) 11 | (:require [com.hypirion.conduit :refer [await yield conduit]])) 12 | 13 | (defn taking [n] 14 | (conduit 15 | (dotimes [_ n] 16 | (yield (await))))) 17 | ``` 18 | 19 | The actual `take` transducer is implemented like this: 20 | 21 | ```clj 22 | (defn take 23 | ([n] 24 | (fn [rf] 25 | (let [nv (volatile! n)] 26 | (fn 27 | ([] (rf)) 28 | ([result] (rf result)) 29 | ([result input] 30 | (let [n @nv 31 | nn (vswap! nv dec) 32 | result (if (pos? n) 33 | (rf result input) 34 | result)] 35 | (if (not (pos? nn)) 36 | (ensure-reduced result) 37 | result))))))) 38 | ...) 39 | ``` 40 | 41 | For some examples, see the 42 | [clojure.core ports](https://github.com/hyPiRion/clj-conduit/wiki/clojure.core-ports) 43 | – all of Clojure's transducers implemented with conduits. For a more complex 44 | example, you can see an implementation of a 45 | [simple moving average](https://github.com/hyPiRion/clj-conduit/wiki/examples#simple-moving-average) 46 | with conduits. 47 | 48 | ## Quickstart 49 | 50 | If you want the full story, you can read my blogpost 51 | [From Transducers to Conduits and Back Again](http://hypirion.com/musings/transducers-to-conduits-and-back) 52 | which explains in detail the entire library and the rationale for it. If you 53 | just want basic usage, you can continue reading this section. 54 | 55 | To use clj-conduit, you need to add the following to your `:dependencies`: 56 | 57 | ```clj 58 | [com.hypirion/conduit "0.1.0"] 59 | ``` 60 | 61 | The most essential part of the conduit library is `conduit`, `await` and 62 | `yield`. I usually prefer to refer them directly, like so: 63 | 64 | ```clj 65 | (ns my.namespace 66 | (:refer-clojure :exclude [await]) 67 | (:require [com.hypirion.conduit :refer [await yield conduit]])) 68 | ``` 69 | 70 | Note that since there's already a function named `await` in clojure.core, we 71 | exclude it to avoid the warning message. 72 | 73 | `conduit` is a macro that transforms the code inside into transducer. It will 74 | work as if the code is a process. To receive values from upstream, call `await`. 75 | It can be considered as a "blocking" read, in which it will block until there is 76 | a new value available. If there is no more values to read, it will block forever 77 | (but contrary to Java threads, this will be garbage collected). 78 | 79 | To send values downstream, call `yield`. This will indefinitely block if 80 | downstream doesn't want any more values (and will be garbage collected). 81 | 82 | If the conduit code block finishes or blocks on a `yield`, then it signals 83 | upstream that it is done. 84 | 85 | The smallest valuable conduit example is probably an implementation of the 86 | transducer `map`. It is implemented as follows: 87 | 88 | ```clj 89 | (defn mapping [f] 90 | (conduit 91 | (while true 92 | (yield (f (await)))))) 93 | ``` 94 | 95 | Note that we have to wrap the `(yield (f (await)))` part in a while true-loop to 96 | avoid reading just a single value. If it was implemented as follows, it would 97 | only read (at most) a single value and send it down: 98 | 99 | ```clj 100 | (defn mapping1 [f] 101 | (conduit 102 | (yield (f (await))))) 103 | ``` 104 | 105 | Note that you must call `yield` and `await` directly inside a `(conduit ...)` 106 | block, just like ` (f#) 137 | (ioc/aset-all! REDUCER-IDX rf# 138 | ioc/BINDINGS-IDX captured-bindings#))] 139 | (fn 140 | ([] (rf#)) 141 | ([acc#] 142 | (if (or (ioc/finished? state#) 143 | (identical? (ioc/aget-object state# XDUCER-STATE-IDX) 144 | :await-parked)) 145 | (rf# acc#) 146 | (do 147 | (ioc/aset-all! state# XDUCER-STATE-IDX :complete 148 | ACC-IDX acc#) 149 | (ioc/run-state-machine state#) 150 | ;; this will run until we're done, so no worries here. 151 | (let [acc# (unreduced (ioc/aget-object state# ACC-IDX))] 152 | ;; cleanup 153 | (ioc/aset-all! state# ACC-IDX nil) 154 | (rf# acc#))))) 155 | ([acc# input#] 156 | (if (ioc/finished? state#) 157 | (reduced acc#) 158 | (do 159 | (case (ioc/aget-object state# XDUCER-STATE-IDX) 160 | (:no-input :await-parked) 161 | (ioc/aset-all! state# XDUCER-STATE-IDX :no-input 162 | ACC-IDX acc# 163 | ioc/VALUE-IDX input#) 164 | (ioc/aset-all! state# XDUCER-STATE-IDX :input 165 | ACC-IDX acc# 166 | INPUT-IDX input#)) 167 | ;; previous call moved 168 | (ioc/run-state-machine state#) 169 | (let [acc# (ioc/aget-object state# ACC-IDX)] 170 | (ioc/aset-all! state# ACC-IDX nil INPUT-IDX nil) 171 | acc#)))))))) 172 | -------------------------------------------------------------------------------- /test/com/hypirion/conduit_test.clj: -------------------------------------------------------------------------------- 1 | (ns com.hypirion.conduit-test 2 | (:require [clojure.test :refer :all] 3 | [com.hypirion.conduit :refer :all]) 4 | (:refer-clojure :exclude [await])) 5 | 6 | (defn- taking 7 | "Transducer version of take, implemented via conduit." 8 | [n] 9 | (conduit 10 | (dotimes [_ n] 11 | (yield (await))))) 12 | 13 | (defn- dropping 14 | "Transducer version of drop, implemented via conduit." 15 | [n] 16 | (conduit 17 | (dotimes [_ n] 18 | (await)) 19 | (while true 20 | (yield (await))))) 21 | 22 | (def ^:private catting 23 | "cat implemented via conduit." 24 | (conduit 25 | (while true 26 | (doseq [val (await)] 27 | (yield val))))) 28 | 29 | (defn- partitioning-by 30 | "Transducer version of partition-by, implemented via conduit." 31 | [f] 32 | (conduit 33 | (let [first-val (await)] 34 | (loop [vs [first-val] 35 | to-cmp (f first-val)] 36 | (if-let-await! v 37 | (let [new-to-cmp (f v)] 38 | (if (= to-cmp new-to-cmp) 39 | (recur (conj vs v) to-cmp) 40 | (do (yield vs) 41 | (recur [v] new-to-cmp)))) 42 | ;; no more values, so flush out vs and exit 43 | (yield vs)))))) 44 | 45 | (defn- partitioning 46 | "Transducer version of partition, implemented via conduit. 47 | 48 | Presumably not that efficient." 49 | ([n] 50 | (partitioning n n)) 51 | ([n step] 52 | (conduit 53 | (loop [acc []] 54 | (let [chunk (loop [acc' acc] 55 | (if (= (count acc') n) 56 | acc' 57 | (recur (conj acc' (await)))))] 58 | (yield chunk) 59 | (recur (vec (drop step chunk)))))))) 60 | 61 | ;; This one is slightly scary: (take 10 (sequence natural-numbers [])) diverges, 62 | ;; which _makes sense_ but may be slightly surprising. (sequence (comp 63 | ;; natural-numbers (take 10)) []) works as intended though. 64 | (def natural-numbers 65 | (conduit 66 | (loop [n 0] 67 | (yield n) 68 | (recur (inc' n))))) 69 | 70 | (deftest conduit-test 71 | (testing "basic usage" 72 | (is (= (reduce + (take 10 (range))) 73 | (transduce (taking 10) + (range)))) 74 | (is (= (reduce + (drop 10 (range 100))) 75 | (transduce (dropping 10) + (range 100)))) 76 | (is (= (partition 2 1 (range 10)) 77 | (sequence (partitioning 2 1) (range 10))))) 78 | (testing "short circuiting on infinities" 79 | (is (= (range 10) (sequence (taking 10) (range)))) 80 | (is (= (range 10) (sequence (comp natural-numbers (taking 10)) nil))) 81 | (is (= (range 10 20) (sequence (comp (dropping 10) (taking 10)) (range))))) 82 | (testing "composition" 83 | (is (= (take 10 (partition 2 1 (range))) 84 | (sequence (comp (partitioning 2 1) (taking 10)) (range)))) 85 | (is (= (sequence (comp (partitioning 2 1) cat) (range 10)) 86 | [0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9]))) 87 | (testing "completion" 88 | (is (= (sequence (partitioning-by identity) [0 1 1 2 2 3 4 3 3]) 89 | [[0] [1 1] [2 2] [3] [4] [3 3]])) 90 | (is (= (sequence (partitioning-by identity) []) 91 | [])))) 92 | --------------------------------------------------------------------------------