angelino/ufpb-27a-sdc

27a SDC UFPB

Ferramentas:

• https://leiningen.org/#install
• https://www.jetbrains.com/idea/
• https://cursive-ide.com/userguide/

Libs

• https://github.com/clojure/data.json
• https://github.com/cgrand/enlive

Refs

• http://www.clojurenewbieguide.com/
• https://clojuredocs.org/
• https://practical.li/blog/posts/web-scraping-with-clojure-hacking-hacker-news/
• https://medium.com/geekculture/scraping-web-product-data-with-clojure-6594a86c2f00

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Intro Clojure

History

• https://clojure.org/about/history

• Rich Hickey 2007

• Lisp

• Functional Programming

• Hosted JVM (CLR/JS*)

• Concurrency

• 2009 (v1.0) / 2022 (v1.11) ~ 12 anos

  • retro compatível (aka Java)
    • o que foi feito em versões mais antigas continua funcionando nas versões mais recentes
  • 1.10.0-alpha5 drops support for Java 6 and 7 and makes Java 8 the minimum requirement. Compilation will produce Java 8 level bytecode (which will not run on earlier versions of Java). This is the first change in bytecode version since Clojure 1.6. (2014)

• Killer Feature: Data Processing/Transformation

Setup

• REPL + Setup IDE

  • compilar/avaliar expressões - (ALT + SHIFT + E)
  • compilar/avaliar top form/definicoes/fns (ALT + SHIFT + P)
  • compilar/avaliar todo o ns/load do arquivo para memória (ALT + SHIFT + L)
  • switch do ns para o arquivo corrente do editor (ALT + SHIFT + R)

• estrutura projeto (lein new)

• gestão libs/deps

Intro

• https://clojure.org/guides/learn/syntax

values & collections

• https://clojure.org/guides/learn/sequential_colls
• https://clojure.org/guides/learn/hashed_colls

expressions, fn

• https://clojure.org/guides/learn/functions

ns, def, let

• https://clojure.org/guides/learn/namespaces

flow

• https://clojure.org/guides/learn/flow

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Functional Toolkit

• Map (n->n)

• Filter (n->[n..0])

• Reduce* (n->A)

• https://purelyfunctional.tv/courses/3-functional-tools/

• GOTO 2018 • Functional Programming in 40 Minutes • Russ Olsen

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Demo

(ns clj-workshop.core
  (:require [clojure.data.json :as json]))

(def url "https://raw.githubusercontent.com/jeffreylancaster/game-of-thrones/master/data/characters.json")

(def content (slurp url))

(keyword "asdfsdaf")
(def characters (:characters (json/read-str content
                                            :key-fn
                                            keyword)))

(count characters)

(take 3 characters)

(reverse (sort (set (map :characterName characters))))

(filter (fn [character]
          (clojure.string/starts-with? character "King"))
        (map :characterName characters))

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IMDB scrapper

https://www.imdb.com/chart/top

(ns clj-workshop.imdb
  (:require [net.cgrand.enlive-html :as html]
    [clojure.string :as str])
  (:import (java.net URL)))

(def url (URL. "https://www.imdb.com/chart/top"))

(def content (html/html-resource url))

(def rows (html/select content [:table :tbody.lister-list :tr]))
(defn- get-row-content [row path]
  (-> (html/select row path)
      first
      :content
      first))

(defn movie [row]
  (let [title (get-row-content row [:td.titleColumn :a])
        year (get-row-content row [:td.titleColumn :span.secondaryInfo])
        rating (get-row-content row [:td.ratingColumn :strong])]
    {:title  title
     :year   (Integer/parseInt
               (-> year
                   (str/replace "(" "")
                   (str/replace ")" "")))
     :rating (Double/parseDouble rating)}))

;; Exploring  

(def movies (map movie rows))

(take 10 (reverse (sort-by :rating movies)))

(count movies)

;; Have fun!!!!  
;  
;1. Quais filmes tiveram uma avaliação igual ou superior a 9? 
;  
;2. Quais filmes foram publicados em 2018?  
;  
;3. Quantos filmes do Piratas do Caribe estão na lista?  
;  
;4. Qual o filme mais antigo encontrado na lista?  
;  
;5. Imprima uma tabela formatada da lista de filmes utilizando (see clojure.pprint).

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