Леонид Шевцов «Clojure в деле»
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This document contains a summary of a talk on using Clojure in projects. The speaker discusses Clojure's immutable, persistent data structures and built-in support for concurrency. He also covers ClojureScript/Om for frontend development, standard libraries, extensibility through DSLs, testing with TDD and ReplDD, and deployment options like Heroku and Docker. The talk provides an overview of Clojure's features and advantages for programming projects.
![(defn project-point-to-line-fraction
"Projection of point on line (returns a real number; 0 = point is closest to v;
1 = point is closest to w; 1>f>0 - on the [v;w] segment; otherwise not on
the [v;w] segment). Returns 0 if v and w is the same point"
[point [v w]]
(let [length2 (dist2 v w)]
(if (< length2 0.00001) ; a point
0
(/ (+ (* (- (:x point) (:x v)) (- (:x w) (:x v)))
(* (- (:y point) (:y v)) (- (:y w) (:y v))))
length2))))](https://image.slidesharecdn.com/leonidshevtsov-150901074311-lva1-app6892/85/Clojure-4-320.jpg)
![Стандартная
библиотека
(defn points-to-segments
"Convert a polyline represented by points
into a vector of segments"
[points]
(into [] (partition 2 1 points)))](https://image.slidesharecdn.com/leonidshevtsov-150901074311-lva1-app6892/85/Clojure-9-320.jpg)
![(facts
"about expr-transform"
(fact
"transforms expressions"
(algebra/expr-transform [:not [:and "x" "y"]]
[:or [:not "x"] [:not "y"]]
(algebra/expr :not [:and "a" "b"]))
=> (algebra/expr :or [:not "a"] [:not "b"])
(algebra/expr-transform [:not [:not "x"]]
"x"
(algebra/expr :not [:not "x"]))
=> "x")](https://image.slidesharecdn.com/leonidshevtsov-150901074311-lva1-app6892/85/Clojure-13-320.jpg)
![(ns jsfp.parser
(:require [clojure.string :as s])
(:import (org.antlr.v4.runtime ANTLRInputStream
CommonTokenStream
BailErrorStrategy)
(org.antlr.v4.runtime.tree ParseTree)
(jsfp ImperativeLanguageLexer
ImperativeLanguageParser)))
(defn antlr-parse [source-code]
(let [lexer (ImperativeLanguageLexer.
(ANTLRInputStream. source-code))
tokens (CommonTokenStream. lexer)
parser (ImperativeLanguageParser. tokens)
proving-structure (.provingStructure parser)]
(if (zero? (.getNumberOfSyntaxErrors parser))
proving-structure
nil)))](https://image.slidesharecdn.com/leonidshevtsov-150901074311-lva1-app6892/85/Clojure-17-320.jpg)
![Самое страшное
(defn expr-match
"Attempts to match expression by a pattern.
Pattern is a structure of [operator param1 [operator param2 param3]...
String params in pattern are matched against any sub-expression, identifier
or primitive
Boolean and numeric params in pattern are matched by equality.
Returns a map of string params to their values, or false if there is no match"
[pattern expression]
(if (identifier? pattern)
{pattern expression}
(if (primitive? pattern)
(and (= expression pattern) {})
(and (expr? expression)
(let [operator (first pattern) params (next pattern)]
(and (= operator (:operator expression))
(let [forward-param-bindings
(map expr-match params (:params expression))
forward-match
(not-any? false? forward-param-bindings)
reverse-param-bindings
(and (not forward-match)
(expr-commutative? expression)
(map expr-match
params
(reverse (:params expression))))
reverse-match
(and reverse-param-bindings
(not-any? false? reverse-param-bindings))
param-bindings
(or (and forward-match forward-param-bindings)
(and reverse-match reverse-param-bindings))]
(and param-bindings (merge-bindings param-bindings)))))))))](https://image.slidesharecdn.com/leonidshevtsov-150901074311-lva1-app6892/85/Clojure-19-320.jpg)
Леонид Шевцов «Clojure в деле»
- 4. (defn project-point-to-line-fraction "Projection of point on line (returns a real number; 0 = point is closest to v; 1 = point is closest to w; 1>f>0 - on the [v;w] segment; otherwise not on the [v;w] segment). Returns 0 if v and w is the same point" [point [v w]] (let [length2 (dist2 v w)] (if (< length2 0.00001) ; a point 0 (/ (+ (* (- (:x point) (:x v)) (- (:x w) (:x v))) (* (- (:y point) (:y v)) (- (:y w) (:y v)))) length2))))
- 5. ФункцияДанные Результат Функция Функция Функция Функция Слой абстракции
- 6. Волшебные структуры данных Иммутабельные, разделяющие память, ленивые
- 8. Удобная работа с функциями Создавать, передавать как параметры, изменять (map #(if %1 %2 %3) conditions xs ys) ((partial perform-calculation config) (-> x x-to-y y-to-z)
- 9. Стандартная библиотека (defn points-to-segments "Convert a polyline represented by points into a vector of segments" [points] (into [] (partition 2 1 points)))
- 12. TDD, ReplDD
- 13. (facts "about expr-transform" (fact "transforms expressions" (algebra/expr-transform [:not [:and "x" "y"]] [:or [:not "x"] [:not "y"]] (algebra/expr :not [:and "a" "b"])) => (algebra/expr :or [:not "a"] [:not "b"]) (algebra/expr-transform [:not [:not "x"]] "x" (algebra/expr :not [:not "x"])) => "x")
- 14. Среда разработки Cursive (Intellij IDEA)
- 16. Библиотеки
- 17. (ns jsfp.parser (:require [clojure.string :as s]) (:import (org.antlr.v4.runtime ANTLRInputStream CommonTokenStream BailErrorStrategy) (org.antlr.v4.runtime.tree ParseTree) (jsfp ImperativeLanguageLexer ImperativeLanguageParser))) (defn antlr-parse [source-code] (let [lexer (ImperativeLanguageLexer. (ANTLRInputStream. source-code)) tokens (CommonTokenStream. lexer) parser (ImperativeLanguageParser. tokens) proving-structure (.provingStructure parser)] (if (zero? (.getNumberOfSyntaxErrors parser)) proving-structure nil)))
- 19. Самое страшное (defn expr-match "Attempts to match expression by a pattern. Pattern is a structure of [operator param1 [operator param2 param3]... String params in pattern are matched against any sub-expression, identifier or primitive Boolean and numeric params in pattern are matched by equality. Returns a map of string params to their values, or false if there is no match" [pattern expression] (if (identifier? pattern) {pattern expression} (if (primitive? pattern) (and (= expression pattern) {}) (and (expr? expression) (let [operator (first pattern) params (next pattern)] (and (= operator (:operator expression)) (let [forward-param-bindings (map expr-match params (:params expression)) forward-match (not-any? false? forward-param-bindings) reverse-param-bindings (and (not forward-match) (expr-commutative? expression) (map expr-match params (reverse (:params expression)))) reverse-match (and reverse-param-bindings (not-any? false? reverse-param-bindings)) param-bindings (or (and forward-match forward-param-bindings) (and reverse-match reverse-param-bindings))] (and param-bindings (merge-bindings param-bindings)))))))))
- 21. Спасибо! Вопросы? Леонид Шевцов Web: http://L-S.me GitHub: @leonid-shevtsov )))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))