Special Characters

"" (stringification) pseudo-operator

467

"" key

501

$" special variable

261, 306

$$ special variable

155

$. special variable

353

$/ special variable

261, 361

$; special variable

$;$ prototype

338

$@ special variable

430

$_ special variable

142–43, 160

& notation in Linogram

495

&@ prototype

337

&;@ prototype

338

&& @rest condition

211

(?!) regex lookahead operator

363

* operator

273, 389, 558

* quantifier

436

* token

376

** operator

426

+ operator

558

+ quantifier

436

+ token

376

-> operator

176

. operator

176

; symbol in prototypes

179

<...> operator

187, 359, 360–65

as rudimentary parser: 359

<=> operator

102, 108

== operator

168, 177–78

for comparing objects: 477

? quantifier

436

@_, modification of

91–92

[...] operator

167

\ (backslash) operator

84–85, 87, 179, 439, 449

\@$$ prototype

293

\@\@ prototype

178

| operator

437

||= operator

106, 106–7

|| operator

103

A

-a command-line option

149

$a and $b variables

345

Abelson, Harold

absolute zero

475

abstract base class

25, 478

abstract syntax tree (AST)

57–58, 393, 400, 408, 437, 553–54, 557

abstraction of functionality

16, 41, 225, 412

accessor method

29, 477

actions

44, 49–50, 53, 446

Adler, David

145

agenda

207–12, 365, 370, 380–81

agenda method, universality of

217

aggregation

19–20

airplane

109

algorithm

10, 11, 287, 471

aliasing

70–71, 81, 92, 112

alternate universe

116–17

alternation of parsers

387–88

ambiguity in arithmetic expressions

amortization

310–13

anchor component of URL

189, 199

anonymous array

31, 50, 81

anonymous functions

19, 76, 79, 86, 123, 258–59, 300, 327, 371, 398, 421, 453, 478

debugger's treatment of: 415–16

append()

162–63

argument isn't numeric warning

108

argument normalizer, inlined cache manager with

90–92

arithmetic expressions

54, 376, 390–435

overview: 390–400
calculator: 400, 424–27
debugging: 415–24
generic-operator parsers: 412–15
grammar for: 376
left recursive: 400–8

arrays

66, 179, 181

contrasted with iterators: 117–18
repeated copying of: 129–30
representation of database rows as: 165–66
looping over: 177–82
contrasted with linked lists: 257

arrow, definition in Linogram

498

Ashton, Elaine

145

assembly language

314

associativity of operators

257, 401–2, 426

AST (abstract syntax tree)

57–58, 393, 393, 400, 408, 437, 553–54, 557

AST_to_string() function

asymmetry, in Linogram parameter specifications

559

atomic expression

436

atomic features in Linogram

494

atomic ray

185

atoms in regexes

436, 439

attribute–value pairs in HTML tags

automatic profiling

111–12

auxiliary parameter

240

B

\b regex metacharacter

272, 439

backslash character

84–85, 87, 179, 439, 449

backtracking

207, 456–65

in regex engine: 364

backtracking parsers

456–65

overview: 456
continuations: 457–61
parse streams: 461–65

backup program

206

bacteriophage

135

bad link detector

191, 192, 194

bad luck

168–69

balanced parentheses

287–88

barbarian

206–7

base case

3, 5, 8, 35, 211, 534

bear

359–60

BEGIN block

338–39, 346, 350–51, 353, 355–56, 502

beginner mode via alternative dispatch table

behavior function

480–81

behavior function in constraint system

479, 480

Bell Labs

563

BFS (breadth-first search)

189, 200, 213–15

binary

1–3, 239–41

binary search

292–93

binding

71–72

bio-informatics

135–39

Bird, Richard

blessing

356, 416, 466, 468–69

blocks

72–73, 390

bare

67–68

as arguments to sort() function: 102

BEGIN

see BEGIN block

disk

see disk blocks

labelled, parser for

541–42

boolean "not" operator

354

Borges, Jorge Luis

417

Boss, the

box, definition in Linogram

497

breadth-first search (BFS)

189, 200, 213–15

browsers

buffer

363

bullet symbol

441

Bunce, Tim

164

Burke, Sean

xv–xvi, 29, 35

bytes

19–20

C

C programming language

xiii–xiv, 67, 75, 79–80, 105, 108–9, 153, 166, 344, 362, 365, 424, 501

auto variables in: 6
for loop: 173
library of: 153, 155

C++ programming language

/c regex modifier flag

367

cache data, expiration of

97–98

cache hit

65, 90, 104, 107

false: 84, 93, 107

cache management overhead

65, 87, 101, 109

cache memory

68, 108

cache miss

65, 91, 95, 107

caching and memoization

63, 65, 83, 90, 101, 268

alternatives to: 101–8
and recursion: 65–66
benefits of speed: 109–13
caveats: 80–84
evangelism: 108–9
inline caching: 66–68
in object methods: 96–99
key generation: 84–95
Memoize module: 70–80
persistent caches: 100–1
quantitative analysis of: 65, 83–84, 90, 101

calculator

54–61, 365–69, 400, 424–27, 435, 469

calculus

302, 305, 314, 319

call frame

231–32

call tree

215–17, 220

callbacks

10, 20, 23, 119, 127, 143–44, 158, 160, 181, 187–88, 190, 225, 227, 326, 371, 386

caller() function

420

canonical form

218–19

canonical order

349–50

cantankerous grandfather

228

cardioid

490

Carp module

186, 522, 532, 558

carriage return

439

carrot

162, 264, 275

CGI

189, 197

CGI::Push module

155

chained lexers

368–74

character classes

273, 281

CHDIR directive in configuration file

chdir() function

Christiansen, Tom

xiii, 129

chromosome

135

chronologically() function

104

chronological order

102–6, 149, 299–300

CIA

184–85

circle, definition in Linogram

499

clauses in grammars

376

cleverness

211

clock, memoized

82–83

clone method in URI::URL

199

closedir() function

closure

76, 124, 326

closure property

76–78

closure operator (*)

273, 286

cmp operator

105

CMYK

63–64

code reference

9–10, 41, 88, 159, see also closure, see also anonymous function

code value (CV)

75–77

coefficient

317, 500, 508

college student, penurious

206

combine()

343–51

comma-separated list

542, 555

comparator function

101–2, 291–92, 350

compiler

comp.lang.perl.misc newsgroup

272

components

compound interest

310–13

compromise

compulsive behavior

453

concatenate() operator

397–98

concatenation

3, 273, 386–87

of parsers: 386–87
of regexes: 273, 275–79, 283–84, 320–21, 438

configuration table

41–42, 47

CONSTANT object

514–16

constant part of equation

500–1, 503

constants

483

constraint networks

487

constraint systems

472

Constraint class

512–13

constraints section in Linogram specification

549–50

Constraint_Set class

513–14

_content key in HTML::TreeBuilder

context

104, 118–19, 159, 165, 182–83, 192, 193

Linogram evaluation environment: 557–60

continuation

457–61

contradiction

509–13

control-backslash character

conversion, decimal to binary

1–3

core dump

cos() function

313–14, 319

cosh() function

320

cost-benefit ratio

110

counting process

131–32

CPAN

104–5, 152, 324, 500

CPU

crab cakes

current matching position of scalar

366–67

curry() function

336, 484

Curry, Haskell B.

327

currying

326–31, 340–43, 346, 350, 353, 484

custom key generation

94–95

cutsort() function

292, 300

cutsorting

288–300

log files: 293–300

cutting function

290–91

CV (code value)

75–77

cwd() function

Cwd module

D

-d operator

124

dangling symbolic link

19, 23–24, 183, 325

database handle

141

database query languages

471

database-query parsing

448–56

overview: 448
lexer: 448–51
parser: 451–56

databases

351–57, 448–56

of cached values: 100–1, 111
flat: 140–53
SQL: 163–68

Data::Dumper module

392

data structure

84, 542

date format, ISO

105

DB_File module

100

DBI module

163, 165–66, 168, 173

DBM

101, 349

dead ends

189

debugger

154–55

debugging

154–55, 415–17, 429, 475, 479, 551

decimal to binary conversion

1–3

declarative programming

471–563

overview

471–72

linear equations

488–90

local propagation networks

472–88

overview: 472–75
implementing: 475–87
problems with: 487–88

declarator in Linogram

545, 548

default action for dispatch table

52–54

Defenestration of Prague

204

defined operator

167

depth-first search

see DFS

derivation of sentence

377

derivative function

305–6, 319, 320, 331

DESTROY method

destructive function

91, 262, 295

destructive method

506, 511

DFS

189, 200, 203, 212–15, 228–29, 383, 403

ambiguity of: 228
bound on size of agenda: 213
contraindications for: 213–14, 379, 403
recursion and: 126, 189, 203, 214, 217
web spiders and: 214, 379

diagnostic messages

13, 42, 201, 260–61, 426, 476

diamond, definition in Linogram

499

die(), throwing exceptions with

430

differential calculus

305, 319

Dijkstra, Edsger Wybe

219

directives

45–46

directory tree

123, 161

directory walking, applications and variations of

16–25

dirhandles

13–15, 118

disk space

diskettes

206

dispatch tables

41–61, 182, 438, 515–16, 520, 528, 551, 559

overview: 41
advantages of: 45–49
calculator: 54–61
configuration file handling: 41–54
default actions: 52–54

division as inverse of multiplication

482–83, 515–16

division by zero

432, 481–82, 517

division of power series

320–24

division of treasure

see partition problem

do-it-yourself

126

do-while loop

243

domain name server

68, 108

DONGS HLAGHAGHL

386–87

doorbell

386–87

drand48() function

153

draw section in Linogram specification

550–51, 553–54

drawables

536–39, 550–51, 553–54

drawables list

554

drawing function

494–95, 537, 561

drunken fraternity brothers

156

du command in Unix

duration (of value)

73–76

E

-e command-line option

149

-e operator

each() operator

182, 349

$elementfunc argument

29, 59–61

email

293–94, 363–64

address: 53–54, 294
header of: 363

empty list

24–25, 36, 166, 179, 346–47, 385

empty string

273, 285, 372, 438, 511

end tag in HTML

Engineering Mathematics Handbook

324

entropy

156

environment

Environment class

538–39

epoch format

295

eq operator

169, 452

Equation class

500–11

Equation::System class

508–12

equations

for Fibonacci numbers: 34
inconsistent: 509–10
linear: 488–513
redundant: 508
roots of: 301
solving: 301, 489
trivial (0=0): 502

equivalence classes

218–19

error diagnosis and recovery in parsing

427–35

escape sequence

eta-conversion

389–90, 391–92, 423, 437

Euclid's algorithm

231

eval operator

46, 86–88, 339, 340, 430, 543

exaggeration

exceptions

430–32

propagation of: 432

execute method in DBI module

168

EXHAUSTED operator

172–73

exhaustion

122, 163, 189, 207, 209, 292, 350, 365, 370, 428, 459

explicit function for: 171–73
synthetic representation of: 167–73

exists operator

107

exp() function

320

expiration of cache data

97–98, 101

explicit exhaustion function

171–73

explicit specification of empty list value

346

explicit stacks

242–53

exponentiation operation

425

Expression class

554

expression parser

55–56, 376, 381–84, 391–415

expressions

376–77

in Linogram: 554–58
F

-f operator

@F special variable

149

façade pattern

170, 172–73

factor of arithmetic expression

394

factorial function

3–6, 241, 314–15, 324

fame and renown

415

family tree

489

Fcntl module

142

features in Linogram

490, 491–98, 520–21, 528–37

Fenchurch

FETCH method

184, 184–85

fetchrow_arrayref method in DBI module

165, 168, 173, 174

Fibonacci numbers

33–35, 65, 67, 243–53

eliminating recursion from calculation of: 243–53

fields in email message header

363

fields in flat text database

140, 148, 150

File::Basename module

191

File::Find module

126

File::ReadBackwards module

152

file system

12, 26

filehandle

115–16, 186

as iterator: 115–17
iterator interface to: 139–40
reading in while loop: 187
tied: 186–87, 299

files

12–13, 18, 23–24, 82, 127, 142

configuration: 41–52
for persistent caching: 100–1
GIF: 64
INI: 117
log: 148–53, 294–95
with octopuses: 161

filters and transforms

157–63

fishing expedition

109

flat databases

148, 452

FlatDB module

140–53, 356, 448

FlatDB::Iterator module

150–52

flat-file database

140, 140–48

floating-point numbers

205–6

Flow chart

157

foolishness

80, 88, 287

forcing the promise

258, 269

for loop, C-style

173

foreach, using to loop over more than one array

177–82

fork() function

Fortran

four-dimensional beings

518

fractions

231

fragment of URL

see "anchor component"

FreezeThaw module

Frege, Gottlob

327

Frequently Asked Question

1, 16, 129

fruit

234

function calls, implementation of

229

function factory

70–71, 199, 259, 325, 385, 406–7

functional vs. object-oriented programming

25–26

functions

custom key generation, for impure functions: 94–95
higher-order: 325, 333
that return references: 81–82
very fast functions: 83–84
whose return values do not depend on their arguments: 80
with reference arguments: 93
with side effects: 80

Funes the Memorious

417

G

\G regex metacharacter

366–67

/g regex modifier flag

366

garbage collection

xiii, 15, 73, 77, 79

Gaussian elimination

500, 502–12

GCD (Greatest Common Divisor)

231

geeks

310

General Electric

generic-operator parsers

412–15

Genomic sequence generator

135–39

getc() function

186

get_links method of HTML::LinkExtor module

189–90

GIF file

63–64

globs

71, 186, 330, 332

glob() operator

119

global filehandle

global variables

5, 47, 49, 142–43, 264, 345, 420–21, 454

effect on recursion: 5–6, 13–14
filehandles as: 13–14, 15, 46
hashes instead of: 51
random number generator as: 156

Goff, Jeff

217

golden ratio

golden_rectangle, definition in Linogram

499

goto

232, 243, 466

grammar

376–80

Grasshopper

188–201

greatest common divisor (GCD)

231–33

grep() function

333–35

grocery bags

Guttman, Uri

152

H

hack

hairy code

414

Hall, Joseph

106

Hamming problem

269–72

Hamming, Richard W.

269

hash

20, 23, 27, 39, 51, 66–67, 83, 89, 112, 200, 235, 296, 479, 494–95, 512, 518, 561

as dispatch table: 44
cache: 64–67, 69, 71, 96, 101
for canonicalizing value: 218
iterator component of: 119, 182
tied: 100, 416
power set of: 235–36

hash key

84, 93, 97

hash slice

144

hash value computation

head of linked list

256, 375

header of email message

363

header of flat-file database

140

headers of HTML document

hexadecimal

hierarchical data

12–15, 128, 203, 530

Hietaniemi, Jarkko

234–35

high school

300, 312, 489

higher-order functions

325, 333

currying: 325–57
reduce() and combine(): 343–51

hline, definition in Linogram

496

hoax

Hoefler, Jonathan

204

Hoefler Type Foundry

204

hook

171, 188, 201, see also callback

HTML

26–33, 59–61, 179, 188–89, 326–27

HTML::LinkExtor module

188, 190

HTML::TreeBuilder module

27, 27–29

HTTP

150

httpd log file

148–49

Human Genome Project

135

hyperlinks

188–97, 200, 214

I

if-else tree

42–44, 56, 59, 245

impure function

94–95

INCLUDE directive in configuration file

incrementing numerals

132

India

299

infinite loop

3, 117, 308, 403, 477, 506

infinite sequence of integers

260

infinite streams

255–324

overview: 255
hamming problem: 269–72
lazy linked lists: 257–63
Newton-Raphson method: 300–13
power series: 313–24
recursive streams: 263–69
regex string generation: 272–300

infix form of expression

ingenuity

48, 68, 124–26, 134, 179, 207, 323

INI file

117

inline caching

66–68

inlined cache manager, with argument normalizer

90–92

inlining

86–88, 90–92, 106

internal stack

125

intrinsic constraints

520–22, 534–35

Intrinsic_Constraint_Set class

521–22

Introduction to Functional Programming

i-number

294

investment banking

96–98, 106–7

IOU

259–60

IRC

16, 272

is_in() example

is_scalar method

531

is_special() function

170

isa method

ISO date format

105

iteration, C model of

173–74

iterators

115–201

overview: 115
alternative interfaces to: 177–87
converting recursive functions to: 203–53
examples: 126–57
exhaustion of: 122
filehandle iterators: 139–40
filters and transforms of: 157–63
flat-file database: 140–48
for permutations: 128–35
genomic sequence generator: 135–39
homemade: 119–26
introduction: 115–19
kicking: 121, 157, 160, 185, 195
random number generators: 153–57
rewinding: 255
searching databases backwards: 148–53
semipredicate problem: 163–76
web spiders: 187–201
J

jargon

377

Junko

K

KEEPER label for HTML elements

30–31, 326

key generation

84–95

overview: 84–88
functions with reference arguments: 93
partitioning: 93–94

key-generation method

keys() function

119

kicking an iterator

121, 157, 160, 185, 195

kindof() accessor in Linogram

514

Kleene closure

273

Knuth, Donald E.

154, 309

L

-l operator

labeled block

541–42

Latin

80, 207

laws of programming

lazy linked lists

257–63

left-associative operator

426

left recursion

400–8, 403–4, 409

left-recursive grammar rules

403–4

Leler, Wm

xvi

lemniscate

490

Leonardo of Pisa (Fibonacci)

lexer, Perl's

450–51

lexers

365–75, 441–42, 448–51, 540

overview: 359–60
chained: 368–74
emulating <> operator: 360–65
peeking: 374–75

lexical analysis

see lexers

lexical closure

lexical filehandle

lexical variables

5–6, 14, 67, 73, 92, 418

lexicality

72–73, 79

lexing

see lexers

line, definition in Linogram

494

linear equations

488–90

linked lists

255–57

head: 256
lazy: 257–63
splicing into: 257
tail: 256

linogram

490–500

overview

490–500

equations

500–14

feature types

530–39

missing features

560–63

parser

539–60

overview: 539–40
declarations: 545–54
definitions: 543–44
expressions: 554–60
required extensions: 541–42
programs: 543

scalar types

531–32

%TYPES

542

values

514–30

overview: 514–16
constant values: 516–18
feature values: 520–21
feature-value methods: 527–30
intrinsic constraints: 521–22
synthetic constraints: 522–27
tuple values: 518–20

Lisp programming language

xiii–xiv, 107

list assignment as condition

165–66

list context

104, 119, 159, 165, 182–83, 192, 193

list expressions

390

List::Util module

343–47

literal regexes

274

local() operator

142–43, 160, 306

local propagation networks

472–88

overview: 472–75
implementing: 475–87
problems with: 487–88

log files

148–53, 293–300, 348–49

log() function

320

LOGFILE directive in configuration file

lookahead assertions

439

lookbehind assertions

439

loop control operators

243

love and admiration

lowest-precedence operator

437

ls command in Unix

ls -R command in Unix

Lucas, Edouard

Luke the Hermit

107

LWP::Simple module

188–89, 201

M

-M operator

82–83

m//g operator

119

Macdonald, John

234

Machol, Richard Morris

228

Macintosh

206

magic variable

184, 186

mailto URL

200

maintenance programmers

make_counter example

77–79

malloc() function

166

map() function

124, 157–60, 262, 333–36, 345, 397, 521, 523

Marshall, Edward Waite

marshalling

mask function

170, 172–73

Mastering Algorithms with Perl

234, 293

Math::BigFloat (multiprecision floating-point library)

307, 435

Math::BigRat module

324

Math::Complex module

435

mathematics geeks

310

matrix transformations

500

max() function in Scalar::Util module

343–45

maxstr() function in Scalar::Util module

344

MAYBE label for HTML elements

30–31, 326

meaning of parsed input

376, 384

meiosis

261

memoize() function

89, 111

Memoize module

69–80, 83, 105

memoization

see caching and memoization

memoized clock

82–83

merging streams

270–71, 274–75

Michie, Donald

min() function

343–44

minstr() function

344

ML for the Working Programmer

monster module

morphology

359–60

mortgage

310–13

Mozilla

198

MSIE

198

multiple-list iterator

179

my declaration

5, 13, 67, 72–73

oddity in semantics of: 264

my variable

see lexical variables

mystery

185

N

\n (newline) character

362–63

-n command-line option

149

%N hash for naming parsers

416–23, 467

nasty regex

287

nasty surprises

142, 229, 335, 427

national security

185

network server

68, 94–95, 108, 148, 189

newline character

261, 363, 441

newsgroups

16, 272

Newton, Isaac

301

Newton-Raphson method

300–13

nextval method

176

NEXTVAL operation

115–16, 120–21, 171–73

90-10 rule

110

nodes

212–13, 215–17, 225–28

in AST: 393, 400
in HTML::TreeBuilder object: 27–29
of linked list: 256–63
in local propagation network: 472–74
of notional tree of sentential forms: 377, 380, 382, 403
in outline structure: 442–44

non-reentrant

nonterminal symbols

377

normalization of equations

511

Norvig, Peter

xiii, xv

null function

24, 60

null pointer

166

NULL value in SQL databases

163, 165

numerals, canonical form for

219

O

O() notation

103

object constructor methods

75, 81, 184, 187, 501–2, 516, 518, 527

object identity, testing with ==

477

object methods, caching in

96–99

object-oriented (OO) programming

25–26, 75, 96–98

octopuses

81–82, 127–28, 161

oddity

24, 264

odometer method

132–34, 138

OO (object-oriented) programming

see object-oriented programming

open() function

116

opendir() function

operating system

68, 82–83, 149–50

operator overloading

see overloading

operator precedence

357, 372, 393–94, 414–15, 437, 465

optimization

81, 110–11, 171, 204, 209–11, 230–31, 240–41, 253, 322, 332

option checking

201

optional item, parser for

541

orcish maneuver

106

Orwant, Jon

234

out of scope

15, 71–75, 92, 264

outlines

440–48

overload module

357, 467

overloading

356, 416, 465–70

oxcart

109

P

pad

73–77

Pair objects

468

palindromes

214–15

parabola

301–3

Paradigms of Artificial Intelligence Programming

xiii, xv

param declaration in Linogram

560–62

parameter specifications in Linogram

545–49, 552, 559–60

parameters

560–61

parentheses

balanced: 287–88
disambiguating expressions: 54, 58, 437
in output of parser: 393–94, 398
in regex: 364

parse method in HTML::LinkExtor

190

parser function

551

parser operator

390

parser, Perl's

159, 360

Parser module

384

parsing

43, 117–18, 198, 199, 351, 359–470

overview: 359
arithmetic expressions: 390–435
backtracking parsers: 456–65
database-query parsing: 448–56
HTML: 27, 188–90
in general: 376–84
lexers: 359–75
Linogram specifications: 539–57
overloaded operators for: 465–70
recursive-descent parsers: 384–90
regexes: 435–40

partial sums

316

partition problem

35–39, 93–94, 204–12

partitioning

35–39, 93–94

partitions of an integer

217–25, 225–26

comparing: 224

pathfinder.com

198

patterns

131, 135, see also regexes

Paulson, Lawrence

penurious college student

206

performance

63–64, 80, 93, 106, 110, 266–68, 332, 453

period of random-number generator

154

Perl 6

176

Perl interactive debugger

415

perldoc program

112

permutations

3–4, 128–35

persistent caches

100–1

pi

317–19, 426

pic program

563

pipe

117

plain text

plumber

206–7

plutonium

94–95, 116

point, definition in Linogram

494

polymorphism

331

pop

126, 223

POPDIR directive in configuration file

46–47

pos() function

366–67

postfix form

postprocessing function

544

PostScript

494, 496

power series

313–24

overview: 313–19
derivatives: 319
symbolic computation: 320–24

power series expansion

313–24

power set

234

powers of 2

265–69

Prague, Defenestration of

204

precedence

357, 437, 465

in arithmetic expressions: 393, 415

predicate function

107, 160–62, 194, 263, 333, 537

pre-emption

223

preprocessor

139

primitive features in Linogram

491, 531–32

print(), as expression

424

printer

print statement

9, 416

printf() function

priority queue

225, 228

private variables

see lexical variables

probability

productions in grammars

376

profiler

110–11

profiling

110–12

Prolog programming language

471

promise

257–58

forcing: 258, 269

propagation network

485–86

prototypes

123, 159, 178, 179, 236, 293, 304, 334, 337–43, 346

proxy server

108

pruning

213, 380, 382, 403

pseudo-random

153

pun

122, 374

punctuation, excessive

144

pure functions

pure virtual methods

push() function

126

PUSHDIR directive in configuration file

Q

q{...} syntax

qmail mail system

293–94, 299

quantification of regexes

437

queue

124–26, 127, 188, 192–93, 201

queue members

193

qw(...) syntax

150

R

rabbits

33–34

Rand() function

153

rand() function

153

random() function

153

random number generation

153–57

Raphson, Joseph

301

readdir() function

118

READLINE method

187

reciprocal

516–17

of power series: 323–24

recursion

and caching: 65–66
as DFS: 215–17
elimination of: 229–53, 348

recursive-descent parsers

384–90

overview: 384
compound operators: 388–90
parser operators: 386–88
very simple parsers: 384–86

recursive streams

263–69, 280, 323

redo

243

re-entrancy

6, 48–49

reentrant function

ref() function

88, 501–2

ref($base) || $base technique

501–2

refactoring

222–23, 234–39, 241, 249–53, 328

reference arguments, functions with

references

9–10, 19, 41, 61, 71, 73–76, 88, 164–65, 467, 502, 554

comparing with ==: 168–69, 178
from pad: 75, 76
functions returning: 81–82
functions accepting: 93
stringification of: 88, 93, 169, 415–16, 467

referrer, fake

193

referring URL

192

regex engine

119, 471

regex string generation

272–300

regexes

119, 143, 272, 286, 361, 365–66, 368–69, 435–40, 471

as examples of declarative programming: 471
as lexers: 365
syntax of: 437

relaxation

488

repetition of parser operation

389–90

return-value parameter

240

reverse() function

135

RGB

63–64

robot policy

197

robots.txt file

197–98

Roode, Eric

xvi, 178, 178–79

root feature

490

root of equation

301

ROOT type in Linogram

542

round-off error

305–6, 307–8, 322

RPN (reverse Polish notation)

54–55

S

-s operator

12, 15

/s regex modifier flag

450

s/// operator

scalar

9, 183–84, 366

tied: 184–85

scalar context

118–19, 159, 183, 192

Scalar::Util module

340

scale() function

329–30

scaling operation

271–72, 320–23, 329–30, 338–39, 503–5, 508, 511, 519–20, 523–24, 528–29

scanning

see lexers

schema

140, 142, 150

Schönfinkel, Moses

327

Schwartz, Randal

xiii, xvi

Schwern, Michael

145

scope

20, 67–68, 71–76, 92, 98, 264, 454

vs. duration: 72–89

searching databases backwards

148–53

secret weapon

185

seed (of pseudo-random number generator)

153

seek() function

142, 148

self-referent stream definition

263–69, 280, 323

semipredicate function

107

semipredicate problem

107, 124, 163, 170

sentences (in grammars)

377

sentential form

377

serialization

set difference

354–56

set_prototype() function

340

shift() function

126, 223

silly examples

184–85, 346, 456–57

sin() function

313–14, 319

sinh() function

320

Sitaker, Kragen

xvi, 453

Slashdot

334

slope

302, 302, 331

sort() function

101, 299, 345

sorting

82, 101–6

partitions

224

comparator functions

101–4, 291–92, 350, 353

tiebreakers in: 103

to obtain canonical form

219

soup, fish-dog-and-carrot

275

spam

363

special cases

32, 110, 211, 236, 284, 345, 409, 455, 478, 505, 536, 556

splines

562

split() function

137, 364–65

sprintf() function

1, 105–6

SQL

163, 168, 471

sqrt() function

300, 307

square, definition in Linogram

498

square() function

srand() function

155

srand48() function

155

srandom() function

155

stack

50, 55–56, 446–47

call stack

125–26, 229–31

explicit simulation of: 38, 242–53

start symbol

376–77

start tag in HTML

stat() function

294

statements as expressions

424–25

static variables

67–68, 124

Stein, Lincoln

135

Storable module

85, 89

STORE method

184–85

streams

259, 261–62, 333, 375

merging: 270–71, 274–75

strftime() function

297

strict 'vars'

345

string

string generator

440

string literals, lexing

449–50

stringification

416, 467

Structure and Interpretation of Computer Programs

StrVal() function in overload module

467

stub functions

71–72, 75–76, 99, 112

subclass

subdirectories

sub-parser

374

substr()

341–42

subtraction as inverse of addition

482–83

subtype definitions

543

sum() function

344–46

Sussman, Gerald Jay

Sybase

145

symbolic links

15, 19, 23–24, 183

dangling: 19, 23–24, 183, 325

symbolic references

51, 550

symbol table

xiii, 70–71, 99, 112

symbols in grammars

376–77

symbols, terminal vs. nonterminal

377

syntactic equivalence of tokens

436

syntactic sugar

122, 123, 172, 259, 374

syntax

176, 397

bizarre: 180
irregularity of Perl's: 453
obsession with: 176

synthetic constraints

520–21, 522–27

Synthetic_Constraint_Set class

522–25

system administrators

149

systems programming

152

T

$^T special variable

82–83

\t (tab) character

450

tab character

450

tac command in Unix

152

_tag key in HTML::TreeBuilder

tags

26, 30–31, 44, 190

tai64n

293, 295

tail of linked list

256

tail-call elimination

229

tangent function

320

tangent line

302

tautology

508

tell() function

148

Tels

307, 324, 435

temperature conversion

472–75, 483, 485–87

terminals

377

terminal symbol

377

terminator pattern

362–65

term of arithmetic expression

394

terms

394

$textfunc argument

29, 59–61

text object in Linogram

561

thrashing

129

three blind mice

308

three-dimensional diagrams in Linogram

518, 556

tie() operator

100, 173, 184–87

tied hashes

100, 416

TIEHANDLE method

187

TIESCALAR method

184

time() function

82–83, 112, 113

Time::HiRes module

112

times() function

113

to-do list

see agenda

tokens

55–57, 137, 359–60

syntactic equivalence of: 436

tokenization

see lexers

token-manufacturing function

371–72, 451

Torkington, Nat

129

tortoise and hare algorithm

309

tourists

Tower of Hanoi

6–11

transcendental functions

313, 409

transforms

see filters and transforms

treasure

35–39, 206–11

trees

12–14, 26–27, 58, 212, 217, 377–80, 402–3, 440, 535

iterator for searching: 225–29
printing: 233–34, 242–43
recursion as search of: 215–17
traversal in various orders: 126

tricks

86, 90, 107–8, 120, 137, 160, 179, 211, 312, 372, 416

trigonometry

322, 489–90, 496

trivial equation (0=0)

502

trivial stream

259

Tuma, Jan J.

324

tuples in Linogram

491, 518–20, 525–30, 555–56, 558

Type class

530–39

Type::Scalar class

531–32

%TYPES hash in Linogram

542–43

typesetting

204

type specimen catalog

204–5

U

ugly code

373

unary minus

555

undef

94, 160, 163–64, 167

undefined variables in calculator program

426

union scale

207

UNIVERSAL::isa() function

88, 181, 258

Unix

15, 117, 150, 294

epoch time format: 295

untagged text

until loop

233

upto()

121–23, 259–60

URI::URL module

199

URL

188–93

bad: 191
fragment part: 199
mailto: 200
referring: 149, 192–93

user-agent

198

user parameter to callback function

49, 51, 60–61, 371, 386, 454

user interfaces

user-supplied key generators, applications of

89–90

V

Value class

515–16

Value::Constant class

516–18, 558

Value::Feature class

527–30, 535, 558–59

Value::Tuple class

518–20

value of parsed input

376, 384–85

values() function

119

variables, static

67–68

VERBOSITY directive

virtual methods

vline, definition in Linogram

497

W

Wadler, Philip

Wall, Larry

xiii, xvi, 145, 176

waste of time

64, 104, 110, 129–30, 190, 197, 230, 265–68, 304, 307, 461

web browsers

68, 108

web robots

see web spiders

web server log

148–50

web spiders

187–201

overview: 187–90
DFS unsuitable for: 214
pursuing only interesting links: 190–92
referring URLs: 192–97
robots.txt: 197–200

$whence argument to seek()

142

while (caller()) loop

420

while loop

13, 187, 209

reading filehandle in: 187
that executes only once: 222

whitespace

27, 441

wildcard

136–37, 136–38

Windows

117

WIRED magazine

228

"without" operator

354–56

wizard

206–7

Wolf Book

234, 293

Wong, Meng

xvi

word boundary

272, 439

Wrigley, Ave

187

WWW::RobotRules module

198–99

WWW::SimpleRobot module

187–88, 200–1

WYSIWYG drawing system

489

Y

yes command in Unix

117

Yukon Territory

179

Z

0e0 trick

107–8

"0 but true"

108