Clojure Tutorial

Posted by Derek Banas on Nov 26, 2017 in Web Design | 0 comments

Clojure is a functional programming language based on Lisp that runs on the JVM. In this one video we’ll cover the core language in one video. Basically I condensed a 300 page book into one 1 hour video.

I covered how to install Emacs here and how to set up Clojure here. Down below you can find both a timestamp list of all topics covered as well as a cheat sheet for the whole tutorial. I hope it helps 🙂

If you find videos like this useful consider donating $1 or simply turn off AdBlocker. Either helps a ton.

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Cheat Sheet

;; Declares a namespace which sets a unique name for your functions
;; Since Clojure runs on the JVM we have to
;; define a class
(ns clojure-tut.core
  (:require [clojure.string :as str])
  (:gen-class))

;; VARIABLES
;; Variables are immutable (value can't change) and they are
;; defined with def and start with letters or underscores
;; and can contain numbers also

(def randVar 10)

;; DATA TYPES
;; Types are assigned based on the value assigned

;; -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807
(def aLong 15) 

;; 4.94065645841246544e-324d to 1.79769313486231570e+308d
(def aDouble 1.23456)

;; A String
(def aString "Hello")

;; true or false
(def aBool true)

;; Get the data type
(type 15)

;; Check if no value (nil)
(nil? aLong)

;; Check if a value is positive
(pos? aLong)

;; Check if a number is negative
(neg? aLong)

;; Check if even
(even? aLong)

;; Check if odd
(odd? aLong)

;; Check if number
(number? aLong)

;; Check if integer
(integer? aLong)

;; Check if float
(float? aLong)

;; Check if zero
(zero? aLong)

;; FORMATTED OUTPUT

(format "This is a string %s" aString)

(format "5 spaces and %5d" aLong)

(format "Leading zeros %04d" aLong)

(format "%-4d left justified" aLong)

(format "3 decimals %.3f" aDouble)

;; STRINGS
  (def str1 "This is my 2nd string")

;; Check if blank
(str/blank? str1)

;; Does string contain "my"
(str/includes? str1 "my")


;; Index of match
(str/index-of str1 "my")

;; Split string into vector using separator or Regex
(str/split str1 #" ")
(str/split str1 #"\d")

;; Join a collection into 1 string with a seperator
(str/join " " ["The" "Big" "Cheese"])

;; Replace all Regex with a string
;; There is also replace-first
(str/replace "I am 42"  #"42" "43")

;; Remove whitespace at beginning and end
;; Also remove newlines with trim-newline
;; Remove left white space triml
;; and right trimr
(str/trim str1)

;; Uppercase
(str/upper-case str1)

;; Lowercase
(str/lower-case str1)

;; LISTS
;; Stores a list of values with multiple data types

(println (list "Dog" 1 3.4 true))

;; Get 1st Value
(println (first (list 1 2 3)))

;; Get rest of values
(println (rest (list 1 2 3)))

;; Get defined index
(println (nth (list 1 2 3) 1))

;; Add values to the right
(println (list* 1 2 [3 4]))

;; Add 1 value to the left
(println (cons 3 (list 1 2)))

;; SETS
;; List of unique values

(println (set '( 1 1 2)))

;; Get an index
(println (get (set '(3 2)) 2))

;; Append a value
(println (conj (set '(3 2)) 1))

;; Is value in set
(println (contains? (set '(3 2)) 3))

;; Remove value from set
(println (disj (set '(3 2)) 2))

;; VECTORS

(println (vector 1 "Dog"))

;; Get index
(println (get (vector 3 2) 1))

;; Append element
(println (conj (vector 1 2) 3))

;; Remove 1st item
(println (pop (vector 3 2)))

;; Return vector from one point to another
(println (subvec (vector 1 2 3 4) 1 3))

;; MAPS
;; Collection of key value pairs

(println (hash-map "Name" "Derek" "Age" 42))

;; Sorted lists sort based on keys
(println (sorted-map 3 42 2 "Banas" 1 "Derek"))

;; Return value mapped to key
(println (get (hash-map "Name" "Derek") "Name"))

;; Get value for the key
(println (find (hash-map "Name" "Derek" "Age" 42) "Name"))

;; Does map contain a key
(println (contains? (hash-map "Name" "Derek") "Age"))

;; Get list of keys
(println (keys (hash-map "Name" "Derek" "Age" 42)))

;; Get values
(println (vals (hash-map "Name" "Derek" "Age" 42)))

;; Merge maps
(println (merge-with + (hash-map "Name" "Derek") (hash-map "Age" 42)))

;; ATOMS
;; With atoms you can change a variables value

(defn atom-ex
  [x]

  ;; Define the atoms value
  (def atomEx (atom x))

  ;; Watchers can be attached to atoms and agents
  ;; to run functions when a value changes
  (add-watch atomEx :watcher
             (fn [key atom old-state new-state]
               (println "atomEx changed from " old-state " to " new-state)))

  ;; Print the value
  (println "1st x" @atomEx)

  ;; Change the value
  (reset! atomEx 10)
  (println "2nd x" @atomEx)

  ;; Change the value using a function
  (swap! atomEx inc)
  (println "Increment x" @atomEx)
  )

;; AGENTS
;; Agents allow you to change values using functions

(defn agent-ex
  []

  ;; Create agent
  (def tickets-sold (agent 0))

  ;; Add a value to an agent
  (send tickets-sold + 15)

  ;; Added because there is a delay often
  (println)
  (println "Tickets " @tickets-sold)

  ;; Wait for the value to update with await-for
  (send tickets-sold + 10)
  (await-for 100 tickets-sold)
  (println "Tickets " @tickets-sold)

  ;; Shutdown running agents
  (shutdown-agents)
  )

;; MATH 

(println (+ 1 2 3)) ;; Add values together
(println(- 5 3 2)) ;; Subtract values
(println(* 2 5)) ;; Multiply Values
(println(/ 10 5)) ;; Divide Values
(println(mod 12 5)) ;; Modulus
(println(inc 5)) ;; Increment
(println(dec 5)) ;; Decrement

(println(Math/abs -10)) ;; Absolute Value
(println(Math/cbrt 8)) ;; Cube Root
(println(Math/sqrt 4)) ;; Square Root
(println(Math/ceil 4.5)) ;; Round up
(println(Math/floor 4.5)) ;; Round down
(println(Math/exp 1)) ;; e to the power of 1
(println(Math/hypot 2 2)) ;; sqrt(x^2 + y^2)
(println(Math/log 2.71828)) ;; Natural logarithm
(println(Math/log10 100)) ;; Base 10 log
(println(Math/max 1 5))
(println(Math/min 1 5))
(println(Math/pow 2 2)) ;; Power

;; Generate random number
(println (rand-int 20))

;; cos, sin, tan acos, asin, atan, cosh, sinh, tanh


;; Perform an operation on a collection
(reduce + [1 2 3])
(reduce - [1 2 3])

(Math/PI)




;; FUNCTIONS
;; Define a function with 1 parameter named name

(defn say-hello
  "Receives a name and responds with Hello Again name"

  ;; Attributes for the function
  [name]

  ;; Output the text and value
  (println "Hello Again"  name))

(defn get-sum
  [x y]

  ;; The output from the last operation is returned
  (+ x y))

;; You can receive an unknown number of parameters
(defn get-sum-more
  ([x y z]
  (+ x y z))

  ([x y]
  (+ x y)))

;; Receive a variable number of parameters in a list
(defn hello-you
  [name]
  ;; Another way to combine strings
  (str "Hello " name))

(defn hello-all
  [& names]

  ;; Pass values to hello-you
  (map hello-you names))

;; DECISION MAKING

;; RELATIONAL OPERATORS
;; = not= < <= > >=
(= 4 5)
(not= 4 5)

;; LOGICAL OPERATORS
;; and or not
(and true false)
(or true false)
(not true)

;; IF THEN ELSE

(defn can-vote
  [age]

  ;; If the statement is true execute the 1st, or 2nd if false
  (if (>= age 18)
    (println "You can Vote")
    (println "You can't Vote")))

(defn can-do-more
  [age]

  ;; You can perform multiple actions with do
  (if (>= age 18)
    (do (println "You can Drive")
        (println "You can Vote"))
    (println "You can't Vote")))

;; WHEN
;; Is used when you want to do many things if true

(defn when-ex
  [tof]

  (when tof
    (println "1st Thing")
    (println "2nd Thing")))

;; COND
;; Check for multiple conditions
(defn what-grade
  [n]
  (cond
    (< n 5) "Preschool"
    (= n 5) "Kindergarten"
    (and (> n 5) (<= n 18)) (format "Go to Grade %d" (- n 5))
    :else "Go to College"))

;; LOOPING
;; WHILE LOOPS
;; Loop while condition is true

(defn one-to-x
  [x]

  ;; Value that increments
  (def i (atom 1))

  ;; Loop while true
  (while (<= @i x)
    (do
      (println @i)

      ;; Increment value
      (swap! i inc))))

;; DOTIMES LOOP
;; Execute a statement a set number of times

(defn dbl-to-x
  [x]

  ;; i is incremented each time through
  (dotimes [i x]
    (println (* i 2))))

;; LOOP LOOP
;; Loop through values using recur to change a value
;; until a condition is no longer true

(defn triple-to-x
  [x y]

  ;; Set starting value of i
  (loop [i x]

    ;; Cycle while true
    (when (< i y)
      (println (* i 3))

      ;; Increment the value
      (recur (+ i 1)))))
              

;; DOSEQ LOOP
;; Iterates through a sequence
(defn print-list

  ;; Holds list passed
  [& nums]

  ;; As you cycle through the list store each item in x
  (doseq [x nums]
    (println x)))

;; FILE I/O

(use 'clojure.java.io)

(defn write-to-file
  [file text]

  ;; with-open opens and closes the file
  ;; and then writes a string to a file
  (with-open [wrtr (writer file)]
    (.write wrtr text)))

(defn read-from-file
  [file]

  ;; We can catch a potential file not found error
  ;; with exception handling

  (try
    ;; Read from a file to a single string
    (println (slurp file))

    ;; Catch the error and print it
    (catch Exception e (println "Error : " (.getMessage e)))))

;; Append text to a file
(defn append-to-file
  [file text]

  (with-open [wrtr (writer file :append true)]
    (.write wrtr text)))

;; Read 1 line at a time
(defn read-line-from-file
  [file]

  (with-open [rdr (reader file)]
    (doseq [line (line-seq rdr)]
      (println line))))
  
;; DESTRUCTURING
;; Binding of values in a data structure to symbols

(defn destruct
  []
  (def vectVals [1 2 3 4])

  ;; Assign values to symbols
  ;; the-rest stores remaining values
  (let [[one two & the-rest] vectVals]
  (println one two the-rest)))

;; STRUCTMAPS
;; Used to define a complex custom type

(defn struct-map-ex
  []

  ;; Define a Struct
  (defstruct Customer :Name :Phone)

  ;; Define a Struct Object
  (def cust1 (struct Customer "Doug" 4125551212))

  ;; You can also assign to specific keys
  (def cust2 (struct-map Customer :Name "Sally" :Phone 5551122))

  (println cust1)

  ;; Access individual fields
  (println (:Name cust2))
  )

;; ADVANCED FUNCTIONS

;; Anonymous Functions
;; Function with no name

;; Create a list by multiplying all values by themselves
(map (fn [x] (* x x)) (range 1 10))

;; Compact anonymous function multiplies everything by 3
(map #(* % 3) (range 1 10))

;; Compact anon with 2 arguments
(#(* %1 %2) 2 3)

;; CLOJURES
;; Return a custom function
;; Run in Repl
;; (defn custom-multiplier
;;  [mult-by]
;;  #(* % mult-by))

;; (def mult-by-3 (custom-multiplier 3))
;; (mult-by-3 3)

;; Where your code starts execution
(defn -main
  "I don't do a whole lot ... yet."
  [& args]

  ;; FUNCTIONS
  ;; Call for the function to execute

  (say-hello "Derek")
  (get-sum 4 5)
  (get-sum-more 1 2 3)
  (hello-all "Doug" "Mary" "Paul")
  (println "Mult by 3")
  
  ;; DECISION MAKING
  (can-vote 17)
  (can-do-more 24)
  (when-ex true)
  (what-grade 19)

  ;; ATOMS
  (atom-ex 5)

  ;; LOOPING
  (one-to-x 5)
  (dbl-to-x 5)
  (triple-to-x 1 5)
  (print-list 7 8 9)

  ;; FILE I/O
  (write-to-file "test.txt" "This is a sentence\n")
  (read-from-file "test.txt")
  (append-to-file "test.txt" "This is another sentence\n")
  (read-line-from-file "test.txt")

  ;; DESTRUCTURING
  (destruct)

  ;; STRUCTMAPS
  (struct-map-ex)

  ;; AGENTS
  (agent-ex)

  ;; TAKE DROP
  (take-drop-ex)
)
(ns tut2.core
  (:gen-class))

(defn take-drop
  []

  ;; FILTERING LISTS
  ;; TAKE DROP TAKE-WHILE DROP-WHILE FILTER
  ;; Remove 1st 2
  (println (take 2 [1 2 3]))

  ;; Remove after the 1st
  (println (drop 1 [1 2 3]))

  ;; Take what matches a condition
  (println (take-while neg? [-1 0 1]))

  ;; Drop what matches a condition
  (println (drop-while neg? [-1 0 1]))

  ;; Return what matches
  (println (filter #(> % 2) [1 2 3 4]))

  (println (rand) 0.5)
  
  )

;; MACROS
;; Macros generate code when you need to define when
;; or if arguments should be evaluated

;; This macro will print different discounts based on
;; if the person is over 65 or not
(defmacro discount
  ([cond dis1 dis2]

   ;; Syntax Quoting tells clojure not to evaluate if, but
   ;; to just return it
   (list `if cond dis1 dis2)))

;; Create (+ 2 5) when passed (2 + 5)
(defmacro reg-math
  [calc]

  (list (second calc) (first calc) (nth calc 2)))

;; Execute multiple statements with do
(defmacro do-more
  [cond & body]

  ;; If condition is true combine and return all past
  ;; statements in a list for execution
  (list `if cond (cons 'do body)))

(defmacro do-more-2
  [cond & body]

  ;; You can surround everything with syntax quoting and
  ;; then unquote single values with ~ and multiples with
  ;; ~@
  `(if ~cond (do ~@body)))


(defn -main
  "I don't do a whole lot ... yet."
  [& args]
  (take-drop)

  ;; MACROS
  (discount (> 25 65) (println "10% off") (println "Full Price"))

  (reg-math (2 + 5))

  ;; macroexpand tells us what the macro does
  (macroexpand `(reg-math (2 + 5)))

  (do-more (< 1 2) (println "Hello") (println "Hello Again"))

  (do-more-2 (< 1 2) (println "Hello") (println "Hello Again"))

  )

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;; Declares a namespace which sets a unique name for your functions

;; Since Clojure runs on the JVM we have to

;; define a class

(ns clojure-tut.core

(:require [clojure.string :as str])

(:gen-class))

;; VARIABLES

;; Variables are immutable (value can't change) and they are

;; defined with def and start with letters or underscores

;; and can contain numbers also

(def randVar 10)

;; DATA TYPES

;; Types are assigned based on the value assigned

;; -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807

(def aLong 15)

;; 4.94065645841246544e-324d to 1.79769313486231570e+308d

(def aDouble 1.23456)

;; A String

(def aString "Hello")

;; true or false

(def aBool true)

;; Get the data type

(type 15)

;; Check if no value (nil)

(nil? aLong)

;; Check if a value is positive

(pos? aLong)

;; Check if a number is negative

(neg? aLong)

;; Check if even

(even? aLong)

;; Check if odd

(odd? aLong)

;; Check if number

(number? aLong)

;; Check if integer

(integer? aLong)

;; Check if float

(float? aLong)

;; Check if zero

(zero? aLong)

;; FORMATTED OUTPUT

(format "This is a string %s" aString)

(format "5 spaces and %5d" aLong)

(format "Leading zeros %04d" aLong)

(format "%-4d left justified" aLong)

(format "3 decimals %.3f" aDouble)

;; STRINGS

(def str1 "This is my 2nd string")

;; Check if blank

(str/blank? str1)

;; Does string contain "my"

(str/includes? str1 "my")

;; Index of match

(str/index-of str1 "my")

;; Split string into vector using separator or Regex

(str/split str1 #" ")

(str/split str1 #"\d")

;; Join a collection into 1 string with a seperator

(str/join " " ["The" "Big" "Cheese"])

;; Replace all Regex with a string

;; There is also replace-first

(str/replace "I am 42" #"42" "43")

;; Remove whitespace at beginning and end

;; Also remove newlines with trim-newline

;; Remove left white space triml

;; and right trimr

(str/trim str1)

;; Uppercase

(str/upper-case str1)

;; Lowercase

(str/lower-case str1)

;; LISTS

;; Stores a list of values with multiple data types

(println (list "Dog" 1 3.4 true))

;; Get 1st Value

(println (first (list 1 2 3)))

;; Get rest of values

(println (rest (list 1 2 3)))

;; Get defined index

(println (nth (list 1 2 3) 1))

;; Add values to the right

(println (list* 1 2 [3 4]))

;; Add 1 value to the left

(println (cons 3 (list 1 2)))

;; SETS

;; List of unique values

(println (set '( 1 1 2)))

;; Get an index

(println (get (set '(3 2)) 2))

;; Append a value

(println (conj (set '(3 2)) 1))

;; Is value in set

(println (contains? (set '(3 2)) 3))

;; Remove value from set

(println (disj (set '(3 2)) 2))

;; VECTORS

(println (vector 1 "Dog"))

;; Get index

(println (get (vector 3 2) 1))

;; Append element

(println (conj (vector 1 2) 3))

;; Remove 1st item

(println (pop (vector 3 2)))

;; Return vector from one point to another

(println (subvec (vector 1 2 3 4) 1 3))

;; MAPS

;; Collection of key value pairs

(println (hash-map "Name" "Derek" "Age" 42))

;; Sorted lists sort based on keys

(println (sorted-map 3 42 2 "Banas" 1 "Derek"))

;; Return value mapped to key

(println (get (hash-map "Name" "Derek") "Name"))

;; Get value for the key

(println (find (hash-map "Name" "Derek" "Age" 42) "Name"))

;; Does map contain a key

(println (contains? (hash-map "Name" "Derek") "Age"))

;; Get list of keys

(println (keys (hash-map "Name" "Derek" "Age" 42)))

;; Get values

(println (vals (hash-map "Name" "Derek" "Age" 42)))

;; Merge maps

(println (merge-with + (hash-map "Name" "Derek") (hash-map "Age" 42)))

;; ATOMS

;; With atoms you can change a variables value

(defn atom-ex

[x]

;; Define the atoms value

(def atomEx (atom x))

;; Watchers can be attached to atoms and agents

;; to run functions when a value changes

(add-watch atomEx :watcher

(fn [key atom old-state new-state]

(println "atomEx changed from " old-state " to " new-state)))

;; Print the value

(println "1st x" @atomEx)

;; Change the value

(reset! atomEx 10)

(println "2nd x" @atomEx)

;; Change the value using a function

(swap! atomEx inc)

(println "Increment x" @atomEx)

)

;; AGENTS

;; Agents allow you to change values using functions

(defn agent-ex

[]

;; Create agent

(def tickets-sold (agent 0))

;; Add a value to an agent

(send tickets-sold + 15)

;; Added because there is a delay often

(println)

(println "Tickets " @tickets-sold)

;; Wait for the value to update with await-for

(send tickets-sold + 10)

(await-for 100 tickets-sold)

(println "Tickets " @tickets-sold)

;; Shutdown running agents

(shutdown-agents)

)

;; MATH

(println (+ 1 2 3)) ;; Add values together

(println(- 5 3 2)) ;; Subtract values

(println(* 2 5)) ;; Multiply Values

(println(/ 10 5)) ;; Divide Values

(println(mod 12 5)) ;; Modulus

(println(inc 5)) ;; Increment

(println(dec 5)) ;; Decrement

(println(Math/abs -10)) ;; Absolute Value

(println(Math/cbrt 8)) ;; Cube Root

(println(Math/sqrt 4)) ;; Square Root

(println(Math/ceil 4.5)) ;; Round up

(println(Math/floor 4.5)) ;; Round down

(println(Math/exp 1)) ;; e to the power of 1

(println(Math/hypot 2 2)) ;; sqrt(x^2 + y^2)

(println(Math/log 2.71828)) ;; Natural logarithm

(println(Math/log10 100)) ;; Base 10 log

(println(Math/max 1 5))

(println(Math/min 1 5))

(println(Math/pow 2 2)) ;; Power

;; Generate random number

(println (rand-int 20))

;; cos, sin, tan acos, asin, atan, cosh, sinh, tanh

;; Perform an operation on a collection

(reduce + [1 2 3])

(reduce - [1 2 3])

(Math/PI)

;; FUNCTIONS

;; Define a function with 1 parameter named name

(defn say-hello

"Receives a name and responds with Hello Again name"

;; Attributes for the function

[name]

;; Output the text and value

(println "Hello Again" name))

(defn get-sum

[x y]

;; The output from the last operation is returned

(+ x y))

;; You can receive an unknown number of parameters

(defn get-sum-more

([x y z]

(+ x y z))

([x y]

(+ x y)))

;; Receive a variable number of parameters in a list

(defn hello-you

[name]

;; Another way to combine strings

(str "Hello " name))

(defn hello-all

[& names]

;; Pass values to hello-you

(map hello-you names))

;; DECISION MAKING

;; RELATIONAL OPERATORS

;; = not= < <= > >=

(= 4 5)

(not= 4 5)

;; LOGICAL OPERATORS

;; and or not

(and true false)

(or true false)

(not true)

;; IF THEN ELSE

(defn can-vote

[age]

;; If the statement is true execute the 1st, or 2nd if false

(if (>= age 18)

(println "You can Vote")

(println "You can't Vote")))

(defn can-do-more

[age]

;; You can perform multiple actions with do

(if (>= age 18)

(do (println "You can Drive")

(println "You can Vote"))

(println "You can't Vote")))

;; WHEN

;; Is used when you want to do many things if true

(defn when-ex

[tof]

(when tof

(println "1st Thing")

(println "2nd Thing")))

;; COND

;; Check for multiple conditions

(defn what-grade

[n]

(cond

(< n 5) "Preschool"

(= n 5) "Kindergarten"

(and (> n 5) (<= n 18)) (format "Go to Grade %d" (- n 5))

:else "Go to College"))

;; LOOPING

;; WHILE LOOPS

;; Loop while condition is true

(defn one-to-x

[x]

;; Value that increments

(def i (atom 1))

;; Loop while true

(while (<= @i x)

(do

(println @i)

;; Increment value

(swap! i inc))))

;; DOTIMES LOOP

;; Execute a statement a set number of times

(defn dbl-to-x

[x]

;; i is incremented each time through

(dotimes [i x]

(println (* i 2))))

;; LOOP LOOP

;; Loop through values using recur to change a value

;; until a condition is no longer true

(defn triple-to-x

[x y]

;; Set starting value of i

(loop [i x]

;; Cycle while true

(when (< i y)

(println (* i 3))

;; Increment the value

(recur (+ i 1)))))

;; DOSEQ LOOP

;; Iterates through a sequence

(defn print-list

;; Holds list passed

[& nums]

;; As you cycle through the list store each item in x

(doseq [x nums]

(println x)))

;; FILE I/O

(use 'clojure.java.io)

(defn write-to-file

[file text]

;; with-open opens and closes the file

;; and then writes a string to a file

(with-open [wrtr (writer file)]

(.write wrtr text)))

(defn read-from-file

[file]

;; We can catch a potential file not found error

;; with exception handling

(try

;; Read from a file to a single string

(println (slurp file))

;; Catch the error and print it

(catch Exception e (println "Error : " (.getMessage e)))))

;; Append text to a file

(defn append-to-file

[file text]

(with-open [wrtr (writer file :append true)]

(.write wrtr text)))

;; Read 1 line at a time

(defn read-line-from-file

[file]

(with-open [rdr (reader file)]

(doseq [line (line-seq rdr)]

(println line))))

;; DESTRUCTURING

;; Binding of values in a data structure to symbols

(defn destruct

[]

(def vectVals [1 2 3 4])

;; Assign values to symbols

;; the-rest stores remaining values

(let [[one two & the-rest] vectVals]

(println one two the-rest)))

;; STRUCTMAPS

;; Used to define a complex custom type

(defn struct-map-ex

[]

;; Define a Struct

(defstruct Customer :Name :Phone)

;; Define a Struct Object

(def cust1 (struct Customer "Doug" 4125551212))

;; You can also assign to specific keys

(def cust2 (struct-map Customer :Name "Sally" :Phone 5551122))

(println cust1)

;; Access individual fields

(println (:Name cust2))

)

;; ADVANCED FUNCTIONS

;; Anonymous Functions

;; Function with no name

;; Create a list by multiplying all values by themselves

(map (fn [x] (* x x)) (range 1 10))

;; Compact anonymous function multiplies everything by 3

(map #(* % 3) (range 1 10))

;; Compact anon with 2 arguments

(#(* %1 %2) 2 3)

;; CLOJURES

;; Return a custom function

;; Run in Repl

;; (defn custom-multiplier

;; [mult-by]

;; #(* % mult-by))

;; (def mult-by-3 (custom-multiplier 3))

;; (mult-by-3 3)

;; Where your code starts execution

(defn -main

"I don't do a whole lot ... yet."

[& args]

;; FUNCTIONS

;; Call for the function to execute

(say-hello "Derek")

(get-sum 4 5)

(get-sum-more 1 2 3)

(hello-all "Doug" "Mary" "Paul")

(println "Mult by 3")

;; DECISION MAKING

(can-vote 17)

(can-do-more 24)

(when-ex true)

(what-grade 19)

;; ATOMS

(atom-ex 5)

;; LOOPING

(one-to-x 5)

(dbl-to-x 5)

(triple-to-x 1 5)

(print-list 7 8 9)

;; FILE I/O

(write-to-file "test.txt" "This is a sentence\n")

(read-from-file "test.txt")

(append-to-file "test.txt" "This is another sentence\n")

(read-line-from-file "test.txt")

;; DESTRUCTURING

(destruct)

;; STRUCTMAPS

(struct-map-ex)

;; AGENTS

(agent-ex)

;; TAKE DROP

(take-drop-ex)

)

(ns tut2.core

(:gen-class))

(defn take-drop

[]

;; FILTERING LISTS

;; TAKE DROP TAKE-WHILE DROP-WHILE FILTER

;; Remove 1st 2

(println (take 2 [1 2 3]))

;; Remove after the 1st

(println (drop 1 [1 2 3]))

;; Take what matches a condition

(println (take-while neg? [-1 0 1]))

;; Drop what matches a condition

(println (drop-while neg? [-1 0 1]))

;; Return what matches

(println (filter #(> % 2) [1 2 3 4]))

(println (rand) 0.5)

)

;; MACROS

;; Macros generate code when you need to define when

;; or if arguments should be evaluated

;; This macro will print different discounts based on

;; if the person is over 65 or not

(defmacro discount

([cond dis1 dis2]

;; Syntax Quoting tells clojure not to evaluate if, but

;; to just return it

(list `if cond dis1 dis2)))

;; Create (+ 2 5) when passed (2 + 5)

(defmacro reg-math

[calc]

(list (second calc) (first calc) (nth calc 2)))

;; Execute multiple statements with do

(defmacro do-more

[cond & body]

;; If condition is true combine and return all past

;; statements in a list for execution

(list `if cond (cons 'do body)))

(defmacro do-more-2

[cond & body]

;; You can surround everything with syntax quoting and

;; then unquote single values with ~ and multiples with

;; ~@

`(if ~cond (do ~@body)))

(defn -main

"I don't do a whole lot ... yet."

[& args]

(take-drop)

;; MACROS

(discount (> 25 65) (println "10% off") (println "Full Price"))

(reg-math (2 + 5))

;; macroexpand tells us what the macro does

(macroexpand `(reg-math (2 + 5)))

(do-more (< 1 2) (println "Hello") (println "Hello Again"))

(do-more-2 (< 1 2) (println "Hello") (println "Hello Again"))

)

Timestamps

00:39 Setup Project 
03:14 Variables / Def
03:47 Data Types
07:19 Formatted Output
10:20 Strings
15:57 Lists
17:56 Sets
19:19 Vectors
20:43 Maps
23:25 Atoms / Watchers
27:25 Agents
30:19 Math
33:00 Basic Functions
37:57 Relational Operators
38:39 Logical Operators
39:07 If
40:00 Do
41:05 When
41:35 Cond
44:22 While
45:37 Dotimes
46:20 Loop
48:22 Doseq
49:21 File I/O
50:44 Exception Handling
55:39 Destructoring
56:49 Struct Maps
58:46 Anonymous Functions
1:00:58 Clojures
1:02:35 Filtering Lists
1:04:20 Macros

00:39 Setup Project

03:14 Variables / Def

03:47 Data Types

07:19 Formatted Output

10:20 Strings

15:57 Lists

17:56 Sets

19:19 Vectors

20:43 Maps

23:25 Atoms / Watchers

27:25 Agents

30:19 Math

33:00 Basic Functions

37:57 Relational Operators

38:39 Logical Operators

39:07 If

40:00 Do

41:05 When

41:35 Cond

44:22 While

45:37 Dotimes

46:20 Loop

48:22 Doseq

49:21 File I/O

50:44 Exception Handling

55:39 Destructoring

56:49 Struct Maps

58:46 Anonymous Functions

1:00:58 Clojures

1:02:35 Filtering Lists

1:04:20 Macros

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