Learn Lisp in One Video

Posted by Derek Banas on Jul 21, 2015 in Web Design | 0 comments

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.

If you like videos like this it helps to tell Google with a click here

Code From the Video

;;;; 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)
   )
)

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

603

604

605

606

607

608

609

610

611

612

613

614

615

616

617

618

619

620

621

622

623

624

625

626

627

628

629

630

631

632

633

634

635

636

637

638

639

640

641

642

643

644

645

646

647

648

649

650

651

652

653

654

655

656

657

658

659

660

661

662

663

664

665

666

667

668

669

670

671

672

673

674

675

676

677

678

679

680

681

682

683

684

685

686

687

688

689

690

691

692

693

694

695

696

697

698

699

700

701

702

703

704

705

706

707

708

709

710

711

712

713

;;;; 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)

)

	Facebook
	YouTube
	Twitter
	LinkedIn

Learn Lisp in One Video

Leave a Reply Cancel reply