Today we will learn Lisp in One video. I’ll cover how to Install Lisp, reading input, Format, Math Functions, Equality, If, Case, When, Unless, Cond, Loop, DoTimes, Lists, Car / Cdr, , Association Lists, Functions, Optional, Receiving Multiple Values, Key, Return-From, Quasi Quoting, MapCar, Returning Multiple Values, Higher Order Functions, Lambda, Macros, Classes, Generic Functions, Inheritance, Arrays, Hash Tables, Structures, File I/O and so much more.
All of the code follows the video below. I hope you like it.
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Code From the Video
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;;;; Lisp stands for List Processing, not ;;;; Lots of Irritating Superflous Parentheses ;;;; Lisps great strength is that you can use data to generate code ;;; ---------- INTRO ---------- ;;; Comment ;; Comment that is indented with code ; Comment after a line of code #|| Multiline Comment ||# ;;; ~% prints a newline with format (format t "Hello world~%") ;;; The format statement starts with t to print to the console ;;; The control sequence begins with a ~ ;;; ~a : Shows the value ;;; ~s : Shows quotes around the value ;;; ~10a : Adds 10 spaces for the value with extra space to the right ;;; ~10@a : Adds 10 spaces for the value with extra space to the left ;;; Print out a string without a newline (print "What's your name ") ;;; Create a variable which receives the value passed by read ;;; A variable name or symbol is made of letters, numbers, and + - _ * = < > ? ! ;;; and are lowercase because Lisp isn't case sensitive ;;; You can't use white space in names because list items are separated ;;; with white space ;;; Asterisks surround global variable names (defvar *name* (read)) ;;; Create a function and say hello to value passed ;;; Your supposed to keep closing parentheses on the same line, but that ;;; is up to you if the code is easier to follow (defun hello-you (*name*) (format t "Hello ~a!~%" *name*) ) ;;; Change the case to capitalize just the first letter (:upcase :downcase) (setq *print-case* :capitalize) (hello-you *name*) ;;; A form is a list with a command function name at the beginning ;;; Everything that follows the command is sent as parameters to the function (+ 5 4) ; = 9 ;;; You can nest a form inside of a form (+ 5 (- 6 2)) ; = 9 ;;; You define a Data Mode command by proceeding with a quote ' '(+ 5 4) ;;; Everything is a list in which each piece is held in a Cons Cell (Consecutive ;;; Cell) [+] [5] [4] [nil] with nil defining the end of the list ;;; Change the value of a variable with setf (setf *number* 6) ;;; You can define variables local to only the let body ;;; (let ((var-1 5) (var-2 10)) (... Body ...)) (let ((var-1 5) (var-2 10)) (print (+ var-1 var-2)) (terpri) ; Prints a newline ) ;;; ---------- FORMAT ---------- (format t "Number with commas ~:d" 10000000) (format t "PI to 5 characters ~5f" 3.141593) (format t "PI to 4 decimals ~,4f" 3.141593) (format t "10 Percent ~,,2f" .10) (format t "10 Dollars ~$ ~%" 10) ;;; ---------- MATH FUNCTIONS ---------- (format t "(+ 5 4) = ~d ~%" (+ 5 4)) (format t "(- 5 4) = ~d ~%" (- 5 4)) (format t "(* 5 4) = ~d ~%" (* 5 4)) (format t "(/ 5 4) = ~d ~%" (/ 5 4)) ; = 5/4 (format t "(/ 5 4.0) = ~d ~%" (/ 5 4.0)) ; = 1.25 (format t "(rem 5 4) = ~d ~%" (rem 5 4)) ; = 1 Returns the remainder (format t "(mod 5 4) = ~d ~%" (mod 5 4)) ; = 1 Returns the remainder (format t "(expt 4 2) = ~d ~%" (expt 4 2)) ; = Exponent 4^2 (format t "(sqrt 81) = ~d ~%" (sqrt 81)) ; = 9 (format t "(exp 1) = ~d ~%" (exp 1)) ; = e^1 (format t "(log 1000 10) = ~d ~%" (log 1000 10)) ; = 3 = Because 10^3 = 1000 (format t "(eq 'dog 'dog) = ~d ~%" (eq 'dog 'dog)) ; = T Check Equality (format t "(floor 5.5) = ~d ~%" (floor 5.5)) ; = 5 (format t "(ceiling 5.5) = ~d ~%" (ceiling 5.5)) ; = 6 (format t "(max 5 10) = ~d ~%" (max 5 10)) ; = 10 (format t "(min 5 10) = ~d ~%" (min 5 10)) ; = 5 (format t "(oddp 15) = ~d ~%" (oddp 15)) ; = T Check if 15 is odd (format t "(evenp 15) = ~d ~%" (evenp 15)) ; = NIL = FALSE Check if 15 is even (format t "(numberp 2) = ~d ~%" (numberp 2)) ; = T Is 2 a number (format t "(null nil) = ~d ~%" (null nil)) ; = T Is something equal to nil ;;; There is also sin, cos, tan, asin, acos, atan ;;; ---------- EQUALITY ---------- ;;; Symbols are compared with eq (defparameter *name* 'Derek) (format t "(eq *name* 'Derek) = ~d ~%" (eq *name* 'Derek)) ;;; Everything else is compared with equal for the most part (format t "(equal 'car 'truck) = ~d ~%" (equal 'car 'truck)) (format t "(equal 10 10) = ~d ~%" (equal 10 10)) (format t "(equal 5.5 5.3) = ~d ~%" (equal 5.5 5.3)) (format t "(equal \"string\" \"String\") = ~d ~%" (equal "string" "String")) (format t "(equal (list 1 2 3) (list 1 2 3)) = ~d ~%" (equal (list 1 2 3) (list 1 2 3))) ;;; equalp can compare strings of any case and integers to floats (format t "(equalp 1.0 1) = ~d ~%" (equalp 1.0 1)) (format t "(equalp \"Derek\" \"derek\") = ~d ~%" (equalp "Derek" "derek")) ;;; ---------- CONDITIONALS ---------- (defparameter *age* 18) ; Create variable age ;;; Relational Operators > < >= <= = ;;; Check if age is greater than or equal to 18 (if (= *age* 18) (format t "You can vote~%") (format t "You can't vote~%")) ;;; How to check for not equal (if (not (= *age* 18)) (format t "You can vote~%") (format t "You can't vote~%")) ;;; Logical Operators : and, or, not (if (and (>= *age* 18) (<= *age* 67) ) (format t "Time for work~%") (format t "Work if you want~%")) (if (or (<= *age* 14) (>= *age* 67) ) (format t "You shouldn't work~%") (format t "You should work~%")) (defparameter *num* 2) (defparameter *num-2* 2) (defparameter *num-3* 2) ;;; You can execute multiple statements in an if with progn (if (= *num* 2) (progn (setf *num-2* (* *num-2* 2)) (setf *num-3* (* *num-3* 3)) ) (format t "Not equal to 2~%")) (format t "*num-2* = ~d ~%" *num-2*) (format t "*num-3* = ~d ~%" *num-3*) ;;; Case performs certain actions depending on conditions (defun get-school (age) (case age (5 (print "Kindergarten")) (6 (print "First Grade")) (otherwise '(middle school)) )) (get-school 5) (terpri) ; Newline ;;; when allows you to execute multiple statements by default (when (= *age* 18) (setf *num-3* 18) (format t "Go to college you're ~d ~%" *num-3*) ) ;;; With unless code is executed if the expression is false (unless (not (= *age* 18)) (setf *num-3* 20) (format t "Something Random ~%") ) ;;; cond is like if else if else (defvar *college-ready* nil) (cond ( (>= *age* 18) ; If T do this (setf *college-ready* 'yes) (format t "Ready for College ~%")) ( (< *age* 18) ; Else If T do this (setf *college-ready* 'no) (format t "Not Ready for College ~%")) (t (format t "Don't Know ~%"))) ; Else do this by default (t is for true) ;;; ---------- LOOPING ---------- ;;; loop executes code a defined number of times ;;; Create a list using numbers 1 through 10 (loop for x from 1 to 10 do(print x)) ;;; Loop until the when condition calls return (setq x 1) (loop (format t "~d ~%" x) (setq x (+ x 1)) (when (> x 10) (return x)) ) ;;; loop for can cycle through a list or iterate commonly ;;; It will execute any number of statements after do (loop for x in '(Peter Paul Mary) do (format t "~s ~%" x) ) (loop for y from 100 to 110 do (print y) ) ;;; dotimes iterates a specified number of times (dotimes (y 12) (print y)) ;;; ---------- CONS CELLS / LISTS ---------- ;;; Link together 2 objects of data (cons 'superman 'batman) ;;; Create a list with list (list 'superman 'batman 'flash) ;;; Add item to the front of another list (cons 'aquaman '(superman batman)) ;;; Get the first item out of a list with car (format t "First = ~a ~%" (car '(superman batman aquaman))) ;;; Get everything but the first item with cdr (format t "Everything Else = ~a ~%" (cdr '(superman batman aquaman))) ;;; Get the 2nd item d = (batman flash joker) a = (batman) (format t "2nd Item = ~a ~%" (cadr '(superman batman aquaman flash joker))) ;;; Get the 3rd item = aquaman (format t "3rd Item = ~a ~%" (caddr '(superman batman aquaman flash joker))) ;;; Get the 4th item (Max you can go) (format t "4th Item = ~a ~%" (cadddr '(superman batman aquaman flash joker))) ;;; Get the 4th item = joker (format t "4th Item = ~a ~%" (cddddr '(superman batman aquaman flash joker))) ;;; Get the 2nd item in the second list ;;; d : (aquaman flash joker) (wonderwoman catwoman) ;;; a : (aquaman flash joker) ;;; d : (flash joker) ;;; a : (flash) (format t "2nd Item 2nd List = ~a ~%" (cadadr '((superman batman) (aquaman flash joker) (wonderwoman catwoman)))) ;;; Get the 3rd item in the 2nd list = joker (format t "3rd Item 2nd List = ~a ~%" (cddadr '((superman batman) (aquaman flash joker) (wonderwoman catwoman)))) ;;; = T Is something a list (format t "Is it a List = ~a ~%" (listp '(batman superman))) ;;; Is 3 a member of the list (format t "Is 3 in the List = ~a ~%" (if (member 3 '(2 4 6)) 't nil)) ;;; Combine lists into 1 list (append '(just) '(some) '(random words)) ;;; Push an item on the front of a list (defparameter *nums* '(2 4 6)) (push 1 *nums*) ;;; Get the nth value from a list (format t "2nd Item in the List = ~a ~%" (nth 2 *nums*)) ;;; Create a plist which uses a symbol to describe the data (defvar superman (list :name "Superman" :secret-id "Clark Kent")) ;;; This list will hold heroes (defvar *hero-list* nil) ;;; Adds items to our list (push superman *hero-list*) ;;; Cycle through all heros in the list and print them out (dolist (hero *hero-list*) ;; Surround with ~{ and ~} to automatically grab data from list (format t "~{~a : ~a ~}~%" hero) ) ;;; ---------- ASSOCIATION LIST ---------- ;;; The hero name represents the key (defparameter *heroes* '((Superman (Clark Kent)) (Flash (Barry Allen)) (Batman (Bruce Wayne)))) ;;; Get the key value with assoc (format t "Superman Data ~a ~%" (assoc 'superman *heroes*)) ;;; Get secret identity (format t "Superman is ~a ~%" (cadr (assoc 'superman *heroes*))) (defparameter *hero-size* '((Superman (6 ft 3 in) (230 lbs)) (Flash (6 ft 0 in) (190 lbs)) (Batman (6 ft 2 in) (210 lbs)))) ;;; Get height (format t "Superman is ~a ~%" (cadr (assoc 'Flash *hero-size*))) ;;; Get weight (format t "Batman is ~a ~%" (caddr (assoc 'Batman *hero-size*))) ;;; ---------- FUNCTIONS ---------- ;;; Create a function that says hello (defun hello () (print "Hello") (terpri)) ; Newline (hello) ;;; Get average (defun get-avg (num-1 num-2) (/ (+ num-1 num-2) 2 )) (format t "Avg 10 & 50 = ~a ~%" (get-avg 10 50)) ;;; You can define some parameters as optional in a function with &optional (defun print-list (w x &optional y z) (format t "List = ~a ~%" (list w x y z)) ) (print-list 1 2 3) ;;; Receive multiple values with &rest (defvar *total* 0) (defun sum (&rest nums) (dolist (num nums) (setf *total* (+ *total* num)) ) (format t "Sum: ~a ~%" *total*) ) (sum 1 2 3 4 5) ;;; Keyword parameters are used to pass values to specific variables (defun print-list(&optional &key x y z) (format t "List: ~a ~%" (list x y z)) ) (print-list :x 1 :y 2) ;;; Functions by default return the value of the last expression ;;; You can also return a specific value with return-from followed by the ;;; function name (defun difference (num1 num2) (return-from difference(- num1 num2)) ) (format t "10 - 2 = ~a ~%" (difference 10 2)) ;;; Get Supermans data ;;; When you use ` you are using quasiquoting which allows you to switch from ;;; code to data mode ;;; The function between ,() is code mode (defun get-hero-data (size) (format t "~a ~%" `(,(caar size) is ,(cadar size) and ,(cddar size)))) (defparameter *hero-size* '((Superman (6 ft 3 in) (230 lbs)) (Flash (6 ft 0 in) (190 lbs)) (Batman (6 ft 2 in) (210 lbs)))) (get-hero-data *hero-size*) ;;; Check if every item in a list is a number (format t "A number ~a ~%" (mapcar #'numberp '(1 2 3 f g))) ;;; You can define functions local only to the flet body ;;; (flet ((func-name (arguments) ;;; ... Function Body ...)) ;;; ... Body ...) (flet ((double-it (num) (* num 2))) (double-it 10)) ;;; You can have multiple functions in flet (flet ((double-it (num) (* num 2)) (triple-it (num) (* num 3))) (format t "Double & Triple 10 = ~d~%" (triple-it (double-it 10))) ) ;;; labels is used when you want to have a function call itself, or if you want ;;; to be able to call another local function inside a function (labels ((double-it (num) (* num 2)) (triple-it (num) (* (double-it num) 3))) (format t "Double & Triple 3 = ~d~%" (triple-it 3)) ) ;;; Return multiple values from a function (defun squares (num) (values (expt num 2) (expt num 3))) ;;; Get multiple values from a function (multiple-value-bind (a b) (squares 2) (format t "2^2 = ~d 2^3 = ~d~%" a b) ) ;;; Higher Order Functions ;;; You can use functions as data (defun times-3 (x) (* 3 x)) (defun times-4 (x) (* 4 x)) ;;; Pass in the function without attributes just like a variable (defun multiples (mult-func max-num) ;; Cycle through values up to the max supplied (dotimes (x max-num) ;; funcall is used when you know the number of arguments (format t "~d : ~d~%" x (funcall mult-func x)) )) (multiples #'times-3 10) (multiples #'times-4 10) ;;; ---------- LAMBDA ---------- ;;; The lambda command allows you to create a function without giving it a name ;;; You can also pass this function just like you pass variables ;;; Multiply every item in a list (mapcar (lambda (x) (* x 2)) '(1 2 3 4 5)) ;;; ---------- MACROS ---------- ;;; A function runs when it is called to execute, while a macro is compiled ;;; first and is available immediately like any other lisp built in function ;;; Macros are functions used to generate code rather then perform actions (defvar *num* 2) (defvar *num-2* 0) ;;; It can be irritating to have to use progn with if (if (= *num* 2) (progn (setf *num-2* 2) (format t "*num-2* = ~d ~%" *num-2*) ) (format t "Not equal to 2 ~%")) (defmacro ifit (condition &rest body) ;;; The backquote generates the code ;;; The , changes the condition to code mode from data mode ;;; The &rest body parameter will hold commands in a list ;;; The "Can't Drive" Works as the else `(if ,condition (progn ,@body) (format t "Can't Drive ~%") )) (setf *age* 16) (ifit (>= *age* 16) (print "You are over 16") (print "Time to Drive") (terpri) ) ;;; let can also get confusing with its parentheses (defun add (num1 num2) (let ((sum (+ num1 num2))) (format t "~a + ~a = ~a ~%" num1 num2 sum))) ;;; Define a macro to clean up let (defmacro letx (var val &body body) `(let ((,var ,val)) ,@body)) (defun subtract (num1 num2) (letx dif (- num1 num2) (format t "~a - ~a = ~a ~%" num1 num2 dif))) (subtract 10 6) ;;; ---------- CLASSES ---------- ;;; defclass defines your custom data type ;;; Define the class name and attributes it has (defclass animal () (name sound)) ;;; Create an animal object (defparameter *dog* (make-instance 'animal)) ;;; Set the values for dog (setf (slot-value *dog* 'name) "Spot") (setf (slot-value *dog* 'sound) "Woof") ;;; Get the values for dog (format t "~a says ~a ~%" (slot-value *dog* 'name) (slot-value *dog* 'sound)) ;;; You can define initialization options for objects ;;; :initarg defines the key used to assign to the slot ;;; :initform defines a default value ;;; You can define an error message if an attribute isn't provided ;;; :accessor generates getter and setters for the slot using the name you ;;; provide. ;;; You could use :reader mammal-sound to generate only a getter ;;; You could use :writer (setf mammal-sound) to generate only a setter (defclass mammal () ((name :initarg :name :initform (error "Must provide a name")) (sound :initarg :sound :initform "No Sound" :accessor mammal-sound) ) ) (defparameter *king-kong* (make-instance 'mammal :name "King Kong" :sound "Rawwwr") ) ;;; Output data on the mammal (format t "~a says ~a ~%" (slot-value *king-kong* 'name) (slot-value *king-kong* 'sound)) ;;; Displays an error because name wasn't defined ;;; (defparameter *king-kong* (make-instance 'mammal)) ;;; Create mammal Fluffy (defparameter *fluffy* (make-instance 'mammal :name "Fluffy" :sound "Meow") ) ;;; A generic function has a name and parameter list but no implementation ;;; In Lisp methods don't belong to classes, but instead belong to generic ;;; functions which are responsible for executing the correct method based ;;; on the data passed (defgeneric make-sound (mammal)) (defmethod make-sound ((the-mammal mammal)) (format t "~a says ~a ~%" (slot-value the-mammal 'name) (slot-value the-mammal 'sound)) ) (make-sound *king-kong*) (make-sound *fluffy*) ;;; You can define your own getters and setters ;;; Define setter (defgeneric (setf mammal-name) (value the-mammal)) (defmethod (setf mammal-name) (value (the-mammal mammal)) (setf (slot-value the-mammal 'name) value)) ;;; Define getter (defgeneric mammal-name (the-mammal)) (defmethod mammal-name ((the-mammal mammal)) (slot-value the-mammal 'name)) (setf (mammal-name *king-kong*) "Kong") (format t "I am ~a ~%" (mammal-name *king-kong*)) ;;; Use the auto generated sound getters and setters instead (setf (mammal-sound *king-kong*) "Rawwwwwwwwr") (format t "I say ~a ~%" (mammal-sound *king-kong*)) ;;; Inheritance allows you to inherit all the attributes of the superclass ;;; and call methods that accept the superclass (defclass dog (mammal) ()) (defparameter *rover* (make-instance 'dog :name "Rover" :sound "Woof") ) (make-sound *rover*) ;;; ---------- ARRAYS ---------- ;;; Create an array with 3 storage areas (defparameter names (make-array 3)) ;;; Add a value to an array (setf (aref names 1) 'Bob) ;;; Get a value in an index (aref names 1) ;;; Make a 3 by 3 array (setf num-array (make-array '(3 3) :initial-contents '((0 1 2) (3 4 5) (6 7 8)))) ;;; Cycle through and print the array (dotimes (x 3) (dotimes (y 3) (print (aref num-array x y)) ) ) ;;; ---------- HASH TABLE ---------- ;;; A collection of key value pairs ;;; Create a hash table (defparameter people (make-hash-table)) ;;; Set the key as 102 and the value to Paul Smith (setf (gethash '102 people) '(Paul Smith)) (setf (gethash '103 people) '(Sam Smith)) ;;; Get the value stored in the key 102 (gethash '102 people) ;;; maphash executes a function on each item ;;; ~% = newline (maphash #'(lambda (k v) (format t "~a = ~a~%" k v)) people) ;;; Remove an entry with the key (remhash '103 people) ;;; ---------- STRUCTURES ---------- ;;; A user defined data type with multiple different data types ;;; Define the data names in the struct (defstruct customer name address id) ;;; Store data in the struct (setq paulsmith (make-customer :name "Paul Smith" :address "123 Main St" :id 1000 )) ;;; Get a value stored (customer-name paulsmith) ;;; Change a value in the struct (setf (customer-address paulsmith) "125 Main St") (write paulsmith) (setq sally-smith-1001 (make-customer :name "Sally Smith" :address "123 Main St" :id 1001 )) ;;; ---------- FILE I O ---------- ;;; Write text to a file ;;; A keyword symbol starts with a colon and it only means itself (with-open-file (my-stream "test.txt" :direction :output ; We are writing to the file :if-exists :supersede) ; If the file exists delete it (princ "Some random Text" my-stream)) ;;; Read data from a file (let ((in (open "test.txt" :if-does-not-exist nil))) (when in (loop for line = (read-line in nil) while line do (format t "~a~%" line)) (close in) ) ) |
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