5 dicas para ajudal-o a programmar in clojure sem stress





Konrad Scorciapino
@konr

0. ambiente de desenvolvimento ligado ao REPL



funcção não funcciona

↓
*mudança*
↓
feedback immediato

rodar hua só funcção

(defn novo-pedido [pedido]
  (let [campos (extrair-campos-uteis pedido)        adequada (adequar campos)]    (salvar adequada))    

user> (novo-pedido amostra)..alguma coisa..
user>

o velho println

(defn novo-pedido [pedido]
  (let [campos (extrair-campos-uteis pedido)        _ (println campos) ;; <--------------        adequada (adequar campos)]    (println adequada) ;; <---------------    (salvar adequada))

user> (novo-pedido amostra)..CAMPOS....ADEQUADA....alguma coisa..
user>

exploração no repl

 user> (extrair-campos-uteis pedido)..CAMPOS..user> (adequar (extrair-campos-uteis pedido))
..ADEQUADA..user> (salvar (adequar (extrair-campos-uteis pedido)))
..RESULTADO..

 user> (-> pedido)..PEDIDO..user> (-> pedido extrair-campos-uteis)..CAMPOS..user> (-> pedido extrair-campos-uteis adequar).. ADEQUADA..user> (-> pedido extrair-campos-uteis adequar salvar)..RESULTADO..

tools.namespace




user=> (use '[clojure.tools.namespace.repl :only (refresh)])
nil

user=> (refresh)
:reloading (com.example.util com.example.app com.example.app-test)
:ok

emacs + lein


> cd /tmp 
> lein new meu-projecto
...
>


1. abrir o archivo no Emacs



2. nrepl-jack-in



o repl abriu!



3. C-c C-k



4. Rodar



5. Voltar pra janella, alterar



6. C-c C-k



7. Rodar!



1. recursos do editor de texto

Emacs


(defvar elpa-packages
  '(starter-kit
    ido
    starter-kit-lisp
    starter-kit-bindings    erc-hl-nicks ercn
    yaml-mode
    dired+

    ;; clj    clojure-mode
    nrepl
    evil evil-leader evil-paredit
    ac-nrepl
    paredit
    rainbow-delimiters
    auto-complete))

clojure-mode


  1. Cores,
  2. Indentação

nrepl.el


  1. jack-in
  2. restart
  3. eval-buffer

rainbow-delimiters



auto-complete & ac-nrepl


...



paredit



evil



2. clojure.repl 



use


user> (use 'clojure.repl)niluser> (use 'clojure.pprint)nil

pst


user> (/ 1 0)
ArithmeticException Divide by zero  clojure.lang.Numbers.divide (Numbers.java:156)
user> (pst)
ArithmeticException Divide by zero
    clojure.lang.Numbers.divide (Numbers.java:156)
	clojure.lang.Numbers.divide (Numbers.java:3691)
	user/eval2826 (NO_SOURCE_FILE:1)
	clojure.lang.Compiler.eval (Compiler.java:6619)
        ...
nil
user>

apropos


user> (apropos "def")
(deftest- deftest default-handler default-middlewares defmethod defstruct defrecord with-redefs definline default-data-readers defn- *verbose-defrecords* with-redefs-fn defn defmacro *default-data-reader-fn* deftype definterface defmulti defonce defprotocol default-streams-impl)
user>

doc


user> (doc defmulti)
-------------------------
clojure.core/defmulti
([name docstring? attr-map? dispatch-fn & options])
Macro
  Creates a new multimethod with the associated dispatch function.
  The docstring and attribute-map are optional.

  Options are key-value pairs and may be one of:
    :default    the default dispatch value, defaults to :default
    :hierarchy  the isa? hierarchy to use for dispatching
                defaults to the global hierarchy
nil
user>

source


user> (source ->)
(defmacro ->
  "Threads the expr through the forms. Inserts x as the
  second item in the first form, making a list of it if it is not a
  list already. If there are more forms, inserts the first form as the
  second item in second form, etc."
  {:added "1.0"}
  ([x] x)
  ([x form] (if (seq? form)
              (with-meta `(~(first form) ~x ~@(next form)) (meta form))
              (list form x)))
  ([x form & more] `(-> (-> ~x ~form) ~@more)))
nil
user>

pprint


user> (pprint '(ns meu-projecto.test (:require [midje.sweet :refer :all] [clojure.pprint :refer :all] [meu-projecto.utils :refer :all] [meu-projecto.core :refer :all ])))
(ns
 meu-projecto.test
 (:require
  [midje.sweet :refer :all]
  [clojure.pprint :refer :all]
  [meu-projecto.utils :refer :all]
  [meu-projecto.core :refer :all]))
nil
user>

print-table


user> (print-table [{:nome "Konrad" :altura "2m"} {:nome "Pedro" :altura "1.75m"} {:nome "Erick" :altura "1.62m"}])

| :altura |  :nome |
|---------+--------|
|      2m | Konrad |
|   1.75m |  Pedro |
|   1.62m |  Erick |
nil
user>

3. seqüestrar variaveis

Truque super util


(def hijacked (ref []))

(defn hijack [thing]
  (dosync (alter hijacked conj thing))
  thing)

No meio de ũa requisição


 (defn nuclear-bomb-access-code [context]   (hijack context)   (let [blablabla ...         inner-thing (hijack ...)         ...]    (hijack (final-function final-result)))

N`hum loop


 (doseq [bla blablabla]   (hijack bla)   ...)

4. ecosystema das interwebs

clojars


clojuredocs


#clojure @ freenode



DuckDuckGo



obvio que o stackoverflow tambem




Dê ũa duckada:

!so clojure android

:)

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