Clojure

2.1.1 Chapter 1 - Getting Started

1. Create a clojure project with Leiningen
   

   lein new app clojure-noob
   

   Generating a project called clojure-noob based on the 'app' template.
   

2. Running the clojure project
   

   lein run
   

   I'm a little teapot!
   

3. Build the project
   

   lein uberjar
   

   Created	/home/moritz/workspace/clojure/clojure-noob/target/uberjar/clojure-noob-0.1.0-SNAPSHOT.jar
   Created	/home/moritz/workspace/clojure/clojure-noob/target/uberjar/clojure-noob-0.1.0-SNAPSHOT-standalone.jar

4. Execute the JAR
   

   java -jar target/uberjar/clojure-noob-0.1.0-SNAPSHOT-standalone.jar
   

   I'm a little teapot!
   

5. Execute code in REPL
   

   lein repl
   

   nREPL server started on port 45749 on host 127.0.0.1 - nrepl://127.0.0.1:45749
   REPL-y 0.3.7, nREPL 0.2.12
   Clojure 1.8.0
   OpenJDK 64-Bit Server VM 1.8.0_191-8u191-b12-0ubuntu0.16.04.1-b12
       Docs: (doc function-name-here)
             (find-doc "part-of-name-here")
     Source: (source function-name-here)
    Javadoc: (javadoc java-object-or-class-here)
       Exit: Control+D or (exit) or (quit)
    Results: Stored in vars *1, *2, *3, an exception in *e
   
   user=> Bye for now!
   

2.1.2 Chapter 2 - Emacs

1. Open the file and start CIDER
   

   (find-file "src/clojure_noob/core.clj")
   (cider-jack-in)
   

   #<process nrepl-server<1>>
   

2.2.1 Episode 1: Laying the Ground

3.1.1 Directory Structure

mkdir -p basic
cp deps.edn basic
cd basic
mkdir -p src
ls

deps.edn
src

3.1.2 Code

(ns hello
  (:require [java-time :as t]))

(defn time-str
  "Returns a string representation of a datetime in the local time zone."
  [instant]
  (t/format
    (t/with-zone (t/formatter "hh:mm a") (t/zone-id))
    instant))

(defn run [opts]
  (println "Hello world, the time is" (time-str (t/instant))))

3.2.1 Library Directory Structure

mkdir -p time-lib
cp deps.edn time-lib
cd time-lib
mkdir -p src
ls

deps.edn
src

3.2.2 Code

(ns hello-time
  (:require [java-time :as t]))

(defn now
  "Returns the current datetime"
  []
  (t/instant))

(defn time-str
  "Returns a string representation of a datetime in the local time zone."
  [instant]
  (t/format
    (t/with-zone (t/formatter "hh:mm a") (t/zone-id))
    instant))

3.2.3 Update Hello World

(ns hello
  (:require [hello-time :as ht]))

(defn run [opts]
  (println "Hello world, the time is" (ht/time-str (ht/now))))

3.2.4 Update Dependencies

{:deps
 {time-lib/time-lib {:local/root "../time-lib"}}}