,,SNOBOL "<,STRI,NG ,ORIENTED SYM,B,OLIC
,LANGUAGE"> IS A FAMILY OF PROGRAMMING
LANGUAGES BUILT AT ,BELL ,TELEPHONE
,LABORATORIES BETWEEN #AIFB AND #AIFG BY
,DAVID ,FARBER1 ,RALPH ,GRISWOLD1 AND
,IVAN ,POLONSKY  AND ,ICON IS ITS DIRECT
DESCENDANT1 DESIGNED BY ,GRISWOLD AT THE
,UNIVERSITY OF ,ARIZONA IN #AIGG#GH4
,BETWEEN THEM THEY INTRODUCED TWO OF THE
MOST QUIETLY CONSEQUENTIAL IDEAS IN THE
HISTORY OF PROGRAMMING3 THE PATTERN AS A
FIRST-CLASS DATA TYPE1 AND GOAL-DIRECTED
EXECUTION DRIVEN BY GENERATORS4 ,EVERY
PROGRAMMER WHO HAS EVER WRITTEN A
REGULAR EXPRESSION1 OR CALLED A ,PYTHON
YIELD1 IS STANDING DOWNSTREAM OF THESE
TWO LANGUAGES4
,,SNOBOL#D1 THE MATURE FORM1 WAS THE
MOST POWERFUL TEXT-PROCESSING LANGUAGE
OF ITS ERA  ARGUABLY OF ANY ERA4 ,IT
TREATED PATTERNS NOT AS STRINGS OF
CRYPTIC NOTATION BUT AS STRUCTURED DATA
THAT COULD BE BUILT1 STORED1 PASSED TO
FUNCTIONS1 AND EVEN MODIFIED WHILE A
MATCH WAS IN PROGRESS4 ,ITS MATCHER
COULD EXPRESS FULL ,BACKUS,NAUR FORM
GRAMMARS  A CLASS OF PROBLEM PROVABLY
BEYOND ORDINARY REGULAR EXPRESSIONS1
WHICH WOULD NOT ACQUIRE COMPARABLE POWER
FOR FORTY YEARS4 ,ICON TOOK THE SAME
ENGINE  SUCCESS1 FAILURE1 AND
BACKTRACKING  AND WRAPPED IT IN THE
,,ALGOL-STYLE SYNTAX THE INDUSTRY HAD
LEARNED TO EXPECT1 ADDING THE GENERATOR1
A CONSTRUCT SO NATURAL THAT ,PYTHON'S
DESIGNERS CITED ,ICON BY NAME WHEN THEY
ADOPTED IT IN #BJJA4.<CITE3 .<,,PEP
#BEE1 8,SIMPLE ,GENERATORS0
"<,SCHEMENAUER1 ,PETERS1 ,HETLAND1 #AH
,MAY #BJJA">1 LISTS ,ICON AMONG THE
GENERATORS' DIRECT INSPIRATIONS4.>.>
,THIS ARTICLE TELLS THE WHOLE STORY3 THE
LANGUAGE ITSELF1 ITS HISTORY AND
LIFETIME1 AND THE CONCEPTS IT GAVE THE
WORLD  PATTERN MATCHING1 GOAL-DIRECTED
PROGRAMMING1 GENERATORS1 AND THE ENTIRE
TRADITION OF STRING-PROCESSING LANGUAGES
THAT FOLLOWED4
,THE WORLD BEFORE STRINGS
,TO UNDERSTAND WHAT ,,SNOBOL DID1 YOU
HAVE TO REMEMBER WHAT PROGRAMMING LOOKED
LIKE WHEN IT ARRIVED4 ,THE LANGUAGES OF
THE #AIEJ;S WERE BUILT FOR NUMBERS4
,,FORTRAN "<#AIEG"> PROCESSED ARRAYS OF
FLOATING-POINT VALUES2 ITS STRING
HANDLING WAS1 CHARITABLY1 AN
AFTERTHOUGHT  TEXT LIVED IN FIXED-LENGTH
FIELDS MANIPULATED THROUGH FORMAT
STATEMENTS4 ,,COBOL "<#AIEI"> THOUGHT IN
RECORDS3 FIXED-LAYOUT ROWS OF DATA FOR
PAYROLL AND INVENTORY4 ,,ALGOL "<#AIEH1
#AIFJ"> GAVE THE WORLD BLOCK STRUCTURE
AND RECURSION  AND ESSENTIALLY NO
STRINGS AT ALL4
,BUT COMPUTERS WERE ALREADY DROWNING IN
TEXT3 PROGRAMS THEMSELVES1 DATA RECORDS1
NATURAL LANGUAGE4 ,THE FIRST PEOPLE TO
NOTICE WERE THE LINGUISTS4 ,AT ,,MIT IN
#AIEG1 ,VICTOR ,YNGVE'S GROUP BUILT
,,COMIT1 THE FIRST LANGUAGE DESIGNED
SPECIFICALLY TO MANIPULATE STRINGS 
MOTIVATED BY THE DREAM OF MACHINE
TRANSLATION1 WHICH IN THOSE OPTIMISTIC
YEARS SEEMED A FEW YEARS FROM SOLVED4
,,COMIT TREATED TEXT AS SOMETHING TO BE
REWRITTEN BY RULES3 MATCH A FRAGMENT OF
THE INPUT AGAINST A PATTERN1 REPLACE IT
WITH SOMETHING ELSE1 AND REPEAT4 ,THAT
SINGLE IDEA  FIND THIS1 REPLACE IT WITH
THAT  IS THE SEED OF EVERYTHING IN THIS
ARTICLE4
,,COMIT WAS BRILLIANT AND AWKWARD IN
ROUGHLY EQUAL MEASURE4 ,ITS NOTATION WAS
DENSE1 ITS EXECUTION SLOW1 AND ITS
PORTABILITY NONEXISTENT4 ,A SECOND EARLY
LANGUAGE1 ,,TRAC "<#AIFD">1 PURSUED
MACROS AND TEXT GENERATION4 ,THE STAGE
WAS SET FOR SOMEONE TO DO STRING
PROCESSING PROPERLY  AND THE PEOPLE WHO
DID WERE NOT LINGUISTS AT ALL1 BUT
RESEARCHERS AT THE MOST FERTILE
LABORATORY IN THE HISTORY OF COMPUTING4
,BELL ,TELEPHONE ,LABORATORIES IN THE
#AIFJ;S WAS A PLACE WHERE A RESEARCHER
COULD BE HANDED A PROBLEM1 A MAINFRAME1
AND EFFECTIVELY NO SUPERVISION4 ,THE
,PROGRAMMING ,RESEARCH ,STUDIES
DEPARTMENT AT THE ,HOLMDEL1 ,NEW ,JERSEY
SITE  SIX PEOPLE  SAT INSIDE AN
INSTITUTION THAT IN A SINGLE DECADE
PRODUCED THE TRANSISTOR'S SUCCESSORS1
,UNIX1 ;,C1 INFORMATION THEORY'S MATURE
FORM1 AND HALF THE THEORETICAL
FOUNDATION OF THE DIGITAL CENTURY4
,COMPUTING THERE MEANT PUNCHED CARDS1
BATCH QUEUES1 AN ,,IBM #GJIJ SHARED BY A
BUILDINGFUL OF RESEARCHERS1 AND
TURNAROUND MEASURED IN THE TIME IT TOOK
TO WALK A CARD DECK TO THE MACHINE ROOM
AND FIND YOUR PRINTOUT IN A BIN4
,INTERACTIVE TERMINALS WERE A RUMOR4
,YOU GOT A FEW SHOTS A DAY2 EACH ONE HAD
TO COUNT1 WHICH IS PRECISELY THE
ENVIRONMENT IN WHICH DENSE1 EXPRESSIVE
NOTATION THRIVES4
,BELL ,LABS AND THE BIRTH OF ,,SNOBOL
.<FIGURE3 ,BELL ,LABS1 ,HOLMDEL1 ,NEW
,JERSEY  THE ,EERO ,SAARINEN 8BIGGEST
MIRROR EVER0 WHERE ,,SNOBOL WAS BORN
"<PHOTO3 ,WIKIMEDIA ,COMMONS1 ,,CC
,,BY-,,SA">.>
,IN THE FALL OF #AIFB1 THREE MEMBERS OF
THE SIX-PERSON ,PROGRAMMING ,RESEARCH
,STUDIES DEPARTMENT AT ,BELL ,LABS IN
,HOLMDEL1 ,NEW ,JERSEY  ,DAVID ,FARBER1
,RALPH ,GRISWOLD1 AND ,IVAN ,POLONSKY 
WERE FRUSTRATED4 ,THEIR ACTUAL WORK
INVOLVED THE SYMBOLIC MANIPULATION OF
POLYNOMIALS1 SYMBOLIC INTEGRATION1 AND
THE STUDY OF ,MARKOV CHAINS4 ,THEIR TOOL
WAS ,,SCL1 A LANGUAGE WRITTEN BY
DEPARTMENT HEAD ,CHESTER ,LEE  SLOW1
LOW-LEVEL1 AND PRODUCING 8VOLUMES OF
CODE FOR EVEN SIMPLE PROJECTS40 ,THEY
CONSIDERED ADOPTING ,,COMIT1 FOUND IT
WANTING1 AND DID WHAT ,BELL ,LABS PEOPLE
DID IN THAT GOLDEN AGE3 THEY WROTE THEIR
OWN LANGUAGE4.<CITE3 ,RALPH ;,E4
,GRISWOLD1 .<8,A ,HISTORY OF THE
,,SNOBOL ,PROGRAMMING ,LANGUAGES01 ,,ACM
,,SIGPLAN ,NOTICES #AC3#H "<,AUGUST
#AIGH">1 AND THE ,,HOPL PAPER ,GRISWOLD
"<#AIHA">  THE STANDARD PRIMARY SOURCES
ON ,,SNOBOL'S ORIGINS4.>.>
,THE FIRST VERSIONS RAN ON THE LAB'S
,,IBM #GJIJ MAINFRAME IN EARLY #AIFC1
AND BY SUMMER THE LANGUAGE WAS IN USE
ACROSS ,BELL4 ,IT HAD ONE DATA TYPE  THE
STRING  NO FUNCTIONS1 NO DECLARATIONS1
ALMOST NO ERROR CONTROL1 AND A SYNTAX OF
BEAUTIFUL SIMPLICITY3 EVERY STATEMENT
WAS A PATTERN MATCH WITH AN OPTIONAL
REPLACEMENT AND AN OPTIONAL BRANCH4 ,ITS
AUTHORS CALLED IT A PERSONAL TOOL4
,TOOLS THAT GOOD NEVER STAY PERSONAL4
,,SEXI1 OR HOW ,,SNOBOL GOT ITS NAME
,THE NAMING STORY IS ONE OF COMPUTING'S
GREAT ANECDOTES1 TOLD BY ,FARBER
HIMSELF4 ,THE TEAM FIRST SETTLED ON
,,SEXI  8,SYMBOLIC ,E,XPRESSION
,INTERPRETER40 ,ALL WENT WELL UNTIL THE
DAY ,FARBER SUBMITTED A BATCH JOB2 ON
THE ,,JOB CARD1 IN STANDARD ,BELL ,LABS
STYLE1 HE PUNCHED THE PROGRAM NAME AND
HIS OWN3 ,,SEXI ,FARBER4
@> 8,ONE OF THE ,COMP ,CENTER GIRLS
LOOKED AT IT AND SAID1 ',THAT'S WHAT YOU
THINK4'0
,A NEW NAME WAS REQUIRED4 ,THE TEAM SAT1
TALKED1 DRANK COFFEE1 SHOT RUBBER BANDS4
,AFTER FAR TOO LONG SOMEONE  MOST LIKELY
,RALPH  SAID THEY DIDN'T HAVE 8A
SNOWBALL'S CHANCE IN HELL0 OF FINDING A
NAME4 ,THE ROOM YELLED AT ONCE3 ,,SNOBOL
IN THE SPIRIT OF THE ERA'S ,7-,,BOL0
LANGUAGES4 ,THE EXPANSION CAME AFTER3
,STRI,NG ,ORIENTED SYM,B,OLIC ,LANGUAGE1
A BACKRONYM STRETCHED AS FAR AS IT WOULD
GO4
,THE THREE AUTHORS
.<FIGURE3 ,DAVID ;,J4 ,FARBER IN #BJJH 
CO-CREATOR OF ,,SNOBOL1 LATER 8THE
GRANDFATHER OF THE ,INTERNET0 FOR HIS
WORK ON EARLY DISTRIBUTED SYSTEMS
"<PHOTO3 ,WIKIMEDIA ,COMMONS1 ,,CC">.>
,THE TRIO BEHIND ,,SNOBOL EACH WENT ON
TO NOTABLE CAREERS4 ,DAVID ;,J4 ,FARBER
LEFT ,BELL ,LABS FOR A LONG ACADEMIC
CAREER  AT ,,UC ,IRVINE1 THE ,UNIVERSITY
OF ,DELAWARE1 ,CARNEGIE ,MELLON1 AND
FINALLY THE ,UNIVERSITY OF
,PENNSYLVANIA1 WHERE HE BECAME ONE OF
THE ELDERS OF COMPUTER NETWORKING4 ,HIS
STUDENTS BUILT EARLY PIECES OF THE
,INTERNET'S INFRASTRUCTURE2 THE
COMMUNITY NICKNAMED HIM1 WITH AFFECTION1
A GRANDFATHER OF THE ,INTERNET1 AND HIS
,INTERESTING ,PEOPLE MAILING LIST RAN
FOR DECADES AS THE INDUSTRY'S BACK
CHANNEL4 ,IVAN ;,P4 ,POLONSKY CONTINUED
AT ,BELL ,LABS IN LANGUAGE RESEARCH2 AND
,RALPH ;,E4 ,GRISWOLD  THE MEMBER OF THE
TRIO FOR WHOM STRING LANGUAGES BECAME A
LIFE'S WORK  CARRIED ,,SNOBOL TO THE
,UNIVERSITY OF ,ARIZONA IN #AIGA AND
SPENT THE NEXT THREE DECADES EXTENDING
THE FAMILY THROUGH ,,SL#E1 ,ICON1 AND
,UNICON4 ,HE DIED IN #BJJF1 HAVING
OUT-PUBLISHED1 OUT-IMPLEMENTED1 AND
OUT-TAUGHT NEARLY EVERYONE IN HIS NICHE4
,THE ,,SNOBOL LINEAGE IS UNUSUAL IN
LANGUAGE HISTORY FOR HAVING A SINGLE
CONTINUOUS STEWARD3 NEARLY EVERY IDEA IN
THIS ARTICLE PASSED THROUGH ONE MAN'S
MIND1 TWICE1 TWENTY YEARS APART4
,THE VERSIONS3 ,,SNOBOL #A THROUGH #D
,,SNOBOL EVOLVED QUICKLY  AND ITS EARLY
HISTORY IS A LESSON IN HOW LANGUAGES
ACTUALLY GROW4
,,SNOBOL#A "<#AIFB#FC"> WAS THE PERSONAL
TOOL3 STRING PROCESSING WITH PATTERN
MATCHING AND REPLACEMENT1 ONE DATATYPE1
MINIMAL SYNTAX1 WRITTEN IN ,,IBM #GJIJ
ASSEMBLY4
,,SNOBOL#B "<,APRIL #AIFD"> ADDED
BUILT-IN FUNCTIONS AND THE ABILITY TO
LINK IN EXTERNAL ASSEMBLY CODE4 ,IT WAS
USED MOSTLY INSIDE ,BELL1 THOUGH IT
REACHED AS FAR AS ,,MIT'S ,PROJECT
,,MAC4 ,BUILT-IN FUNCTIONS1 ONCE
PRESENT1 IMMEDIATELY TAUGHT USERS TO
WANT USER-DEFINED ONES4
,,SNOBOL#C "<,JULY #AIFD"> SUPPLIED
EXACTLY THAT  PROGRAMMER-DEFINED
FUNCTIONS  AND BECAME GENUINELY POPULAR4
,OTHER SITES REIMPLEMENTED IT FOR OTHER
MACHINES1 AND INCOMPATIBLE DIALECTS
BLOOMED4 ,SUCCESS HAD CREATED THE
CLASSIC PROBLEM3 THE AUTHORS WERE BEING
BUG-REPORTED AGAINST VERSIONS THEY NEVER
WROTE4
,,SNOBOL#D "<#AIFG"> WAS THE ANSWER AND
THE MASTERPIECE4 ,THE TEAM DECIDED TO
DEFINE THE LANGUAGE ONCE1 COMPLETELY1
AND MAKE IT RUN EVERYWHERE  AN
EXTRAORDINARY DECISION FOR #AIFG4 ,THE
INTERPRETER WAS WRITTEN IN ASSEMBLY1 BUT
THROUGH ASSEMBLER MACROS IT TARGETED AN
ABSTRACT MACHINE3 THE ,,SNOBOL
,IMPLEMENTATION ,LANGUAGE1 OR ,,SIL1 A
GENERALIZATION OF STRING-MANIPULATION
MACROS BY ,DOUGLAS ,MC,ILROY  THE SAME
,MC,ILROY WHO WAS THEN INVENTING PIPES
DOWN THE HALL4 ,TO PORT ,,SNOBOL#D1 YOU
REIMPLEMENTED THE ,,SIL MACROS ON YOUR
MACHINE2 THE WHOLE LANGUAGE CAME ALONG
FOR FREE4 ,,SNOBOL#D WAS RUNNING ON THE
,,IBM #CFJ IN #AIFG AND WAS RAPIDLY
PORTED ESSENTIALLY EVERYWHERE4 ,IT IS
ONE OF THE EARLIEST SERIOUS
VIRTUAL-MACHINE IMPLEMENTATIONS IN
COMPUTING HISTORY  THE ,,JVM'S ANCESTOR1
BY TWO DECADES4
,IT IS WORTH PAUSING ON WHAT ELSE
EXISTED IN #AIFG1 BECAUSE ,,SNOBOL#D'S
AMBITION ONLY REGISTERS AGAINST THE
BACKDROP4 ,,FORTRAN ,,IV WAS FIVE YEARS
OLD4 ,,BASIC WAS THREE4 ,,PL_/,I WAS
NEW4 ,,ALGOL #FJ HAD GIVEN THE WORLD
RECURSION AND BLOCKS BUT NO STRINGS TO
SPEAK OF4 ,,LISP HAD SYMBOLIC
COMPUTATION AND ITS OWN EXOTIC SYNTAX2
,PROLOG WAS STILL FIVE YEARS IN THE
FUTURE1 UNBUILT4 ,INTO THAT WORLD LANDED
A LANGUAGE WITH GARBAGE COLLECTION1 A
PORTABLE VIRTUAL MACHINE1
PROGRAMMER-DEFINED DATATYPES1
ASSOCIATIVE ARRAYS1 RUNTIME CODE
GENERATION1 AND A PATTERN FACILITY
EQUIVALENT TO CONTEXT-FREE GRAMMARS  A
FEATURE LIST THAT READS LIKE A #AIIJ;S
SCRIPTING LANGUAGE'S SALES PITCH1
SHIPPED WHEN THE MOON LANDING WAS STILL
TWO YEARS AWAY4
,MC,ILROY STRUCK TWICE4 ,IN #AIFI HE
INSISTED ,,SNOBOL#D ADD AN
ASSOCIATIVE-ARRAY TYPE  THE TABLE 
DECADES BEFORE 8HASH MAP0 OR
8DICTIONARY0 BECAME EVERY LANGUAGE'S
STANDARD FEATURE4 ,IT ARRIVED AND
STAYED4
,UNDER THE HOOD3 WHAT ,,SNOBOL#D COULD
DO
,BEHIND THE FIVE-PART STATEMENT SAT AN
UNUSUALLY MODERN MACHINE4 ,,SNOBOL#D
SUPPORTED INTEGERS1 LIMITED-PRECISION
REALS1 STRINGS1 PATTERNS1 ARRAYS1
TABLES1 AND PROGRAMMER-DEFINED DATATYPES
THE ,,DATA FUNCTION LET A USER DECLARE
RECORD TYPES WITH NAMED FIELDS1 A
FACILITY COMPARABLE TO ,,COBOL'S RECORDS
AND AHEAD OF ,PASCAL'S4 ,EVERYTHING
LIVED IN A SINGLE GARBAGE-COLLECTED HEAP
AUTOMATIC MEMORY MANAGEMENT ON A #AIFG
MAINFRAME1 WHEN MOST LANGUAGES STILL
TREATED MEMORY AS THE PROGRAMMER'S
PROBLEM4
,MOST STARTLING OF ALL1 ,,SNOBOL#D
STRINGS COULD BE TURNED INTO PROGRAMS AT
RUNTIME4 ,,EVAL EVALUATED A STRING AS AN
EXPRESSION1 AND THE ,,CODE FUNCTION TOOK
A STRING OF ,,SNOBOL SOURCE1 COMPILED IT
INSIDE THE RUNNING PROGRAM1 AND RETURNED
IT AS A CALLABLE VALUE  EVAL-STYLE
METAPROGRAMMING1 OR ,,JIT-COMPILATION
FROM THE USER'S SEAT1 ON A MACHINE THAT
COST MILLIONS AND SHARED AN HOUR AMONG
DOZENS OF USERS4 ,A PROGRAM COULD WRITE
A PROGRAM4 ,THIS PRODUCED THE CELEBRATED
,,SNOBOL FOOT JOKE3 A PROGRAM THAT READS
ITS OWN SOURCE1 STRIPS EVERY LINE
CONTAINING THE LETTER ;E1 RUNS THE
RESULT  AND AMPUTATES ITSELF1 BECAUSE A
SOURCE FILE WITH EVERY ;E REMOVED IS A
FOOT SHORT4 ,DR4 ,DOBB'S COMMEMORATED
THE GENRE AS 8,PROGRAMS ,THAT ,TRANSFORM
,THEIR ,OWN ,SOURCE ,CODE02 ,,SNOBOL#D
MADE SUCH SELF-MODIFICATION ROUTINE
ENOUGH TO JOKE ABOUT4
,THE ,,SPITBOL EXTENSIONS1 LATER
ABSORBED INTO EVERY MODERN
IMPLEMENTATION1 PUSHED FURTHER STILL3
NESTED CONDITIONAL EXPRESSIONS1
IMMEDIATE ASSIGNMENT DURING MATCHING1
AND THE ABILITY FOR A FUNCTION CALLED
MID-PATTERN TO ALTER THE PATTERN BEING
MATCHED4 ,A ,,SNOBOL#D PATTERN WAS LESS
A QUERY THAN A LIVE COMPUTATION WITH
SIDE EFFECTS  THE PATTERN COULD THINK
ABOUT ITSELF WHILE IT RAN4
,WHAT A ,,SNOBOL PROGRAM LOOKS LIKE
,,SNOBOL IS COLUMN-ORIENTED  A
PUNCHED-CARD-ERA LANGUAGE  AND EVERY
STATEMENT HAS THE SAME FIVE PARTS1 ALL
OPTIONAL3
.<FIGURE3 ,ANATOMY OF A ,,SNOBOL
STATEMENT3 LABEL1 SUBJECT1 PATTERN1 "7
OBJECT1 3GOTO TRANSFER  EVERY PART
OPTIONAL.>
,A LABEL MARKS A JUMP TARGET4 ,THE
SUBJECT IS THE STRING UNDER EXAMINATION2
THE PATTERN IS WHAT TO MATCH AGAINST IT2
"7 OBJECT REPLACES WHATEVER MATCHED2 AND
THE 3 TRANSFER SENDS CONTROL TO A LABEL
ON SUCCESS 3;,S"<444">1 ON FAILURE
3;,F"<444">1 OR UNCONDITIONALLY4 ,THAT
IS THE ENTIRE LANGUAGE'S CONTROL FLOW3
THERE IS NO IF1 NO WHILE1 NO FOR  ONLY
MATCH1 AND BRANCH ON THE OUTCOME4
,,OUTPUT "7 8,HELLO1 ,WORLD60 ,,END
,HELLO ,WORLD IS ONE ASSIGNMENT TO THE
PSEUDO-VARIABLE ,,OUTPUT1 WHICH PRINTS
WHATEVER IS ASSIGNED TO IT4 ,SOMETHING
WITH A LITTLE MOTION  GREET THE USER
DIFFERENTLY BY INITIAL3
,,OUTPUT "7 8,WHAT IS YOUR NAME80       
,USERNAME "7 ,,INPUT         ,USERNAME
8;,J0                                   
3;,S"<,,LOVE">         ,USERNAME 8;,K0  
3;,S"<,,HATE"> ,,MEH     ,,OUTPUT "7
8,HI1 ,7 ,USERNAME                      
3"<,,END"> ,,LOVE    ,,OUTPUT "7 8,HOW
NICE TO MEET YOU1 ,7 ,USERNAME         
3"<,,END"> ,,HATE    ,,OUTPUT "7 8,OH4
,IT'S YOU1 ,7 ,USERNAME ,,END
,LINE THREE MATCHES ,USERNAME AGAINST
THE PATTERN 8;,J0  IMPLICITLY ANCHORED1
SO IT MATCHES ONLY IF THE NAME BEGINS
WITH ;,J4 ,ON SUCCESS IT JUMPS TO
,,LOVE2 OTHERWISE IT FALLS THROUGH TO
THE NEXT LINE4 ,THE 3"<,,END"> IS AN
UNCONDITIONAL TRANSFER4 ,A PROGRAM THAT
KEEPS READING UNTIL THE INPUT RUNS OUT
SHOWS THE IDIOM AT FULL STRENGTH 
,,LEN"<#A"> IS A PATTERN THAT SUCCEEDS
ONLY IF AT LEAST ONE CHARACTER REMAINS3
,,OUTPUT "7 8,PRESS RETURN ALONE TO
FINISH0         ,NAME,COUNT "7 #J       
3"<,,GETINPUT"> ,,AGAIN   ,NAME,COUNT "7
,NAME,COUNT "6 #A         ,,OUTPUT "7
8,NAME ,7 ,NAME,COUNT ,73 ,7
,PERSONAL,NAME ,,GETINPUT ,,OUTPUT "7
8,NAME PLEASE3 ,7         ,PERSONAL,NAME
"7 ,,INPUT         ,PERSONAL,NAME
,,LEN"<#A">                             
3;,S"<,,AGAIN">         ,,OUTPUT "7
8,FINISHED4 ,7 ,NAME,COUNT ,7 NAMES
REQUESTED40 ,,END
.<FIGURE3 ,A PUNCHED CARD  ,,SNOBOL'S
NATIVE HABITAT4 ,LABELS AND THE 3
TRANSFER COLUMN ARE A CARD-FORMAT
LANGUAGE'S GRAMMAR.>
,IT LOOKS ALIEN BECAUSE IT IS ALIEN 
THIS IS PROGRAMMING AS A SEQUENCE OF
REWRITE RULES1 CLOSER IN SPIRIT TO
,,COMIT AND TO ,PROLOG'S CLAUSE LOGIC
THAN TO ANYTHING ,,ALGOL-SHAPED4 ,THE
SAME FIVE-PART LINE HANDLES PATTERN
MATCHING1 SUBSTITUTION1 ,I_/,O1 AND
EVERY CONDITIONAL AND LOOP THE PROGRAM
WILL EVER NEED4
,PATTERN MATCHING
,PATTERN MATCHING IS ,,SNOBOL'S REASON
TO EXIST1 AND THE REASON IT STILL
MATTERS4 ,THE IDEA GENERALIZES WHAT A
REGULAR EXPRESSION DOES  FIND STRUCTURE
IN TEXT  AND LIFTS IT INTO THE LANGUAGE
ITSELF4
,A ,,SNOBOL PATTERN IS A FIRST-CLASS
DATA TYPE3 A VALUE LIKE A STRING OR A
NUMBER1 STORED IN VARIABLES1 PASSED TO
FUNCTIONS1 RETURNED FROM FUNCTIONS1
CONCATENATED INTO LARGER PATTERNS1 AND
BUILT AT RUNTIME4 ,TWO OPERATORS
CONSTRUCT THEM3 CONCATENATION
"<ADJACENCY  ,A ;,B MATCHES ,A THEN
;,B"> AND ALTERNATION "<THE _\ OPERATOR 
,A _\ ;,B MATCHES ,A OR ;,B">4 ,PATTERNS
NEST FREELY4 ,THIS LOOKS ORDINARY NOW
BECAUSE ,JAVA,SCRIPT REGEX LITERALS AND
PARSER COMBINATOR LIBRARIES MADE IT
ORDINARY4 ,IN #AIFG IT WAS A DECADE
AHEAD OF EVERYONE4
,THE MATCHER ITSELF IS A BACKTRACKING
ENGINE  THE SAME ALGORITHMIC FAMILY AS
,PROLOG'S RESOLUTION1 DEVELOPED IN THE
SAME YEARS4 ,TRY AN ALTERNATIVE2 IF THE
MATCH LATER FAILS1 BACK UP AND TRY THE
NEXT4 ,,SNOBOL#D PATTERNS CAN CAPTURE
SUBSTRINGS DURING THE MATCH "<PATTERN 4
VARIABLE BINDS THE MATCHED TEXT">1
INVOKE USER FUNCTIONS MID-MATCH THAT CAN
STEER OR EVEN REWRITE THE PATTERN WHILE
IT RUNS1 AND EXPRESS RECURSIVE
STRUCTURES3 A PATTERN CAN CONTAIN A
REFERENCE TO ITSELF4 ,THAT LAST PROPERTY
IS THE CRUCIAL ONE  IT LETS A ,,SNOBOL
PATTERN DESCRIBE A FULL CONTEXT-FREE
GRAMMAR1 THE SAME CLASS AS ,BACKUS,NAUR
FORM4 ,A ,,SNOBOL PROGRAM COULD
IMPLEMENT A LANGUAGE INTERPRETER ALMOST
DIRECTLY FROM ITS PUBLISHED ,,BNF2 A
MACRO ASSEMBLER FOR A THEORETICAL
MACHINE WAS REPORTEDLY A FEW HUNDRED
LINES1 WITH EACH NEW INSTRUCTION COSTING
ONE LINE4.<CITE3 ,JAMES ;,F4 ,GIMPEL1
.<8,A ,THEORY OF ,DISCRETE ,PATTERNS AND
THEIR ,IMPLEMENTATION IN ,,SNOBOL#D01
,COMMUNICATIONS OF THE ,,ACM #AF3#B
"<,FEBRUARY #AIGC">1 #IA#AJJ  THE FORMAL
TREATMENT ESTABLISHING THAT ,,SNOBOL#D
PATTERNS SUBSUME CONTEXT-FREE
GRAMMARS4.>.>
,REGULAR EXPRESSIONS1 BY CONTRAST1 ARE
REGULAR  THE NAME IS A THEOREM1 NOT A
DESCRIPTION4 ,THEY CANNOT MATCH BALANCED
PARENTHESES1 CANNOT PARSE A GRAMMAR1
CANNOT RECURSE4 ,THEY WERE GOOD ENOUGH
FOR 8FIND TEXT LIKE THIS0 AND SO THEY
WON THE POPULAR MARKET2 ,,AWK AND LATER
,PERL CARRIED THEM TO UBIQUITY IN THE
#AIHJ;S AND #IJ;S WHILE ,,SNOBOL'S
RICHER MODEL FADED FROM TEACHING4 ,ONLY
IN ,DECEMBER #BJJG1 WITH RECURSIVE
PATTERNS IN ,PERL #E4AJ1 DID THE
MAINSTREAM FINALLY ACQUIRE WHAT
,,SNOBOL#D HAD SHIPPED IN #AIFG  A
FORTY-YEAR GAP IN WHICH THE LESS CAPABLE
TOOL WAS SIMPLY THE FASHIONABLE ONE4
"9 A ,,SNOBOL#D PATTERN FOR 8WORD WORD0 
A DOUBLED WORD "9 BUILT AS DATA1 MATCHED
AS STRUCTURE         ,,TWO  "7 
,,BREAK"<0 ,7"> 4 ,,FIRST  ,7 ,7 
"9,,FIRST         ,,LINE  8THE THE END0 
,,TWO                             
3;,S"<,,DOUBLE">         ,,OUTPUT "7 8NO
DOUBLED WORD0                           
3"<,,END"> ,,DOUBLE  ,,OUTPUT "7
8DOUBLED3 ,7 ,,FIRST ,,END
,HERE ,,BREAK"<0 ,7"> 4 ,,FIRST MATCHES
UP TO A SPACE AND CAPTURES IT INTO
,,FIRST1 ,7 ,7 MATCHES THE SPACE
LITERALLY1 AND "9,,FIRST MATCHES THE
CAPTURED TEXT AGAIN  THE PATTERN READS
LIKE THE SENTENCE IT DESCRIBES4 ,A
PRACTICAL PARSER FOR 8A COMPLETE NAME
AND INTERNATIONAL POSTAL MAILING
ADDRESS0  THE EXAMPLE THE LITERATURE
LIKED TO GIVE  IS EXPRESSIBLE THE SAME
WAY1 AND WAS4
,THE PRIMITIVE VOCABULARY
,REAL PATTERNS ARE ASSEMBLED FROM A
SMALL VOCABULARY OF BUILT-IN MATCHERS1
EACH ONE A GENERATOR OF POSSIBLE SPANS3
,PRIMITIVE  ,MATCHES   ,,LEN"<;N">  ANY
;N CHARACTERS   ,,SPAN"<8#JABCDEFGHI0"> 
A RUN OF DIGITS  LONGEST POSSIBLE  
,,BREAK"<0 40">  EVERYTHING UP TO A
SPACE OR PERIOD   ,,ANY"<8AEIOU0"> 
EXACTLY ONE VOWEL   ,,NOTANY"<8#JAB0"> 
ONE CHARACTER THAT IS NOT A DIGIT  
,,ARB  ANYTHING  THE RELUCTANT WILDCARD 
,,REM  THE REMAINDER OF THE STRING  
,,POS"<#J">1 ,,RPOS"<#J">  ANCHORED3
START _/ END OF SUBJECT  
,,BAL"<0"<">0">  A BALANCED-PARENTHESES
EXPRESSION  THE SHOWCASE RECURSIVE
PRIMITIVE   ,,FAIL1 ,,SUCCEED1 ,,ABORT 
CONTROL THE MATCH ENGINE ITSELF ,,BAL
DESERVES THE SPOTLIGHT IT ALWAYS GETS3
MATCHING BALANCED DELIMITERS IS THE
CANONICAL PROBLEM THAT BREAKS REGULAR
EXPRESSIONS1 AND ,,SNOBOL#D SHIPPED IT
AS A BUILTIN4 ,COMBINED WITH CONDITIONAL
CAPTURES  PATTERN 4 VARIABLE BINDS TEXT
ON SUCCESS1 PATTERN @S VARIABLE BINDS
CURSOR POSITION  AND THE
ALTERNATION_/CONCATENATION OPERATORS1
THE VOCABULARY SCALES FROM TOKENIZING A
LINE TO PARSING A LANGUAGE4 ,PATTERNS
BEING DATA1 A PROGRAM COULD STORE A
LIBRARY OF GRAMMAR FRAGMENTS IN A TABLE
AND COMPOSE FULL PARSERS AT RUNTIME3
,,DIGIT   "7  ,,ANY"<8#JABCDEFGHI0">    
,,INT     "7  ,,POS"<#J">
,,SPAN"<8#JABCDEFGHI0"> ,,RPOS"<#J">    
,,INPUT   8#DJIF0  ,,INT                
3;,S"<,,ISINT">         ,,OUTPUT  "7
8NOT AN INTEGER0                        
3"<,,END"> ,,ISINT   ,,OUTPUT  "7
8INTEGER60 ,,END
,SCALE THAT SAME TECHNIQUE TO A REAL
GRAMMAR AND THE MACHINERY SHOWS ITS
MUSCLE4 ,A DATE PARSER  8#BE ,DECEMBER
#AGDE0  IS A HANDFUL OF PATTERN
DEFINITIONS1 EACH READABLE AS WHAT IT
DESCRIBES3
,,DIGITS  "7  8#JABCDEFGHI0        
,,DAY     "7  ,,POS"<#J">
,,SPAN"<,,DIGITS"> 4 ;,N  ,7 ,7        
,,MONTHS  "7  8,JANUARY0 _\ 8,FEBRUARY0
_\ 8,MARCH0 _\ 8,APRIL0 "6              
_\  8,MAY0 _\ 8,JUNE0 _\ 8,JULY0 _\
8,AUGUST0 "6               _\ 
8,SEPTEMBER0 _\ 8,OCTOBER0 _\
8,NOVEMBER0 _\ 8,DECEMBER0        
,,DATE    "7  ,,DAY  ,,MONTHS 4 ;,M  ,7
,7  ,,SPAN"<,,DIGITS"> 4 ;,Y 
,,RPOS"<#J">
,,INPUT   ,,DATE                        
3;,S"<,,OK">         ,,OUTPUT  "7 8NOT A
DATE0                            
3"<,,END"> ,,OK      ,,OUTPUT  "7 ;,N ,7
OF ,7 ;,M ,71 ,7 ;,Y ,,END
"6 CONTINUES A DEFINITION ON THE NEXT
LINE4 ,THE WHOLE THING  GRAMMAR
DEFINITION1 MATCH1 CAPTURE1 AND
FORMATTED OUTPUT  FITS IN A DOZEN LINES1
AND THE PATTERN ,,DATE IS ITSELF A VALUE
THAT COULD BE STORED1 COMBINED1 OR
PASSED ELSEWHERE4 ,THIS IS THE
DIFFERENCE A FIRST-CLASS PATTERN TYPE
MAKES3 A REGEX SOLUTION EMBEDS THE SAME
LOGIC AS ONE UNREADABLE STRING2 THE
,,SNOBOL VERSION IS A GRAMMAR1 COMPOSED
LIKE A GRAMMAR1 DEBUGGED LIKE DATA4
,TEXT PROCESSING LANGUAGES
,,SNOBOL#D BECAME THE CANONICAL
TEXT-PROCESSING LANGUAGE  THE TOOL FOR
THE JOBS THE NUMERIC LANGUAGES COULDN'T
SEE4 ,THE PATTERN FIT A NICHE THAT WAS
EXPLODING IN THE #AIGJ;S3 THE DIGITAL
HUMANITIES1 BEFORE THE FIELD HAD THAT
NAME4 ,HUMANISTS NEEDED TO INDEX1
COLLATE1 TRANSLATE1 AND TRANSFORM TEXT
AT SCALE  CONCORDANCES1 STYLISTIC
ANALYSIS1 MACHINE-TRANSLATION
EXPERIMENTS1 CATALOGUES  AND ,,SNOBOL#D
WAS ESSENTIALLY THE ONLY SERIOUS
INSTRUMENT4 ,IT WAS TAUGHT WIDELY AT
,AMERICAN UNIVERSITIES IN THE LATE
#AIFJ;S AND EARLY #AIGJ;S1 AND USED
THROUGH THE #AIGJ;S AND #HJ;S2 ,SUSAN
,HOCKEY'S ,,SNOBOL ,PROGRAMMING FOR THE
,HUMANITIES "<,CLARENDON ,PRESS1 #AIHE">
IS THE PERIOD'S STANDARD TEXTBOOK4
,ITS SECOND HOME WAS LANGUAGE RESEARCH
ITSELF3 COMPILERS1 FORMAL GRAMMARS1 AND
EARLY ARTIFICIAL INTELLIGENCE 
ESPECIALLY MACHINE TRANSLATION AND
NATURAL-LANGUAGE COMPREHENSION1 WHOSE
RESEARCH COMMUNITY RAN ON THE ,,PDP-#AJ
MACHINES WHERE ,,SNOBOL#D LIVED
COMFORTABLY4 ,THE FILE EDITOR OF THE
,MICHIGAN ,TERMINAL ,SYSTEM ADOPTED
,,SNOBOL#D PATTERNS AS ITS SEARCH
LANGUAGE  AN EDITOR WHOSE REGEX
EQUIVALENT WAS A FULL GRAMMAR ENGINE4
,THE TEACHING FOOTPRINT MATTERED AS MUCH
AS THE RESEARCH ONE4 ,A GENERATION OF
STUDENTS MET SERIOUS STRING HANDLING
THROUGH ,,SNOBOL#D IN THE LATE #AIFJ;S
AND EARLY #GJ;S  THE SAME YEARS THEIR
ENGINEERING CLASSMATES WERE MEETING
,,FORTRAN4 ,THREE BOOKS DID THE
CARRYING3 THE 8GREEN BOOK0 ITSELF
"<,GRISWOLD1 ,POAGE @& ,POLONSKY'S ,THE
,,SNOBOL#D ,PROGRAMMING ,LANGUAGE1
#AIFH1 WITH ITS FAMOUSLY
RIGOROUS-BUT-READABLE EXPOSITION">1
,GRISWOLD'S OWN ,MACRO ,IMPLEMENTATION
"<#AIGB"> FOR THE INTERNALS-CURIOUS1 AND
,GIMPEL'S ,ALGORITHMS IN ,,SNOBOL#D
"<#AIGF">1 A GENUINE ALGORITHMS TEXT
THAT HAPPENED TO BE WRITTEN IN A PATTERN
LANGUAGE4 ,EMMER'S ,,SNOBOL#D"6
"<#AIHE"> CARRIED THE LANGUAGE ONTO
PERSONAL COMPUTERS1 AND ,HOCKEY'S
HUMANITIES TEXT INTO SEMINAR ROOMS WHERE
THE MACHINE HAD PREVIOUSLY BEEN A
PUNCH-CARD CURIOSITY4 ,FOR A NICHE
LANGUAGE1 ,,SNOBOL#D WAS UNUSUALLY
WELL-DOCUMENTED  ONE REASON IT STILL
READS WELL TODAY4
,THE GENRE ,,SNOBOL#D DEFINED HAS A
RECOGNIZABLE GENEALOGY AFTERWARD3 ,,AWK
"<#AIGG1 ALSO FROM ,BELL ,LABS">
STREAMLINED THE MATCH-AND-ACT MODEL FOR
LINE-AT-A-TIME FILES2 ,PERL "<#AIHG">
FUSED IT WITH REGEX AND SHELL
CONVENIENCE INTO THE WEB-ERA GLUE
LANGUAGE2 AND EVERY MODERN 8TEXT
MANIPULATION0 FACILITY  SED1 GREP1
,PYTHON'S RE1 ,JAVA,SCRIPT'S REGEXES1 JQ
LIVES SOMEWHERE ON THE SPECTRUM
,,SNOBOL#D STAKED OUT4
,WHY THE BETTER TOOL LOST
,IT IS WORTH ASKING PLAINLY WHY
,,SNOBOL#D FADED WHILE OBJECTIVELY
WEAKER TOOLS PROSPERED1 BECAUSE THE
ANSWER IS A STANDING LESSON IN LANGUAGE
HISTORY3
"9 ,SYNTAX CARRIED THE ERA'S
FINGERPRINTS4 ,COLUMN LAYOUT AND
LABEL-BRANCH FLOW BELONGED TO PUNCHED
CARDS2 ONCE IF_/THEN_/WHILE BECAME THE
INDUSTRY'S MUSCLE MEMORY1 ,,SNOBOL'S
TRANSFER COLUMN READ LIKE ASSEMBLY4 "9
,REGULAR EXPRESSIONS WERE SMALLER4 ,FOR
#IJ.0 OF REAL WORK  FIND THIS STRING1
SPLIT THIS LINE  A COMPACT NOTATION THAT
FIT INSIDE AN EDITOR BEAT A GRAMMAR
ENGINE4 ,THE MARKET FOR 8A COMPLETE NAME
AND INTERNATIONAL POSTAL MAILING
ADDRESS0 WAS REAL BUT NARROW4 "9 ,,AWK
AND ,PERL WERE FREE AND ON THE MACHINE
YOU ALREADY HAD4 ,UNIX MADE THEM
AMBIENT2 ,,SNOBOL#D REMAINED A LANGUAGE
YOU INSTALLED DELIBERATELY4 "9 ,NO
CHAMPION SURVIVED4 ,WHEN ,GRISWOLD'S
GROUP MOVED ON TO ,ICON1 ,,SNOBOL LOST
ITS RESEARCH ENGINE4 ,PERL HAD ,LARRY
,WALL WRITING ANNUAL ,STATE OF THE
,ONION ADDRESSES2 ,,SNOBOL HAD A LIBRARY
OF EXCELLENT BOOKS AND NO MARKETING
DEPARTMENT4
,THE PATTERN RECURS THROUGHOUT THIS
ENCYCLOPEDIA3 TECHNICAL SUPERIORITY
LOSES TO DISTRIBUTION1 CONVENTION1 AND
LUCK  WHICH IS EXACTLY WHY PRESERVING
THE KNOWLEDGE MATTERS4 ,THE BETTER TOOL
DIDN'T DISAPPEAR2 IT JUST STOPPED BEING
LOOKED AT4
.<FIGURE3 ,AN ,,IBM #GJIJ  THE MACHINE
,,SNOBOL#A RAN ON AT ,BELL ,LABS IN
#AIFB#FC "<,,NASA PHOTO">.>
,IMPLEMENTATIONS AND DIALECTS
,THE CLASSIC ,,SNOBOL#D RAN ON THE
,,PDP-#AJ  SLOWLY1 BECAUSE A PORTABLE
INTERPRETER PAYS IN CYCLES4 ,JAMES
,GIMPEL FIXED THAT TWICE4 ,IN #AIGB1 AT
,BELL ,LABS ,HOLMDEL1 HE DESIGNED
,,SITBOL1 A NATIVE ,,PDP-#AJ
IMPLEMENTATION1 AND USED IT AS THE
SEMESTER PROJECT FOR A STRING-PROCESSING
COURSE AT ,STEVENS ,INSTITUTE OF
,TECHNOLOGY "<THE 8,,ST0 IN THE NAME">3
STUDENTS EACH IMPLEMENTED A SLICE IN
,,PDP-#AJ ASSEMBLER1 AND THE FINISHED
INTERPRETER WAS A FULL-FEATURED1
HIGH-PERFORMANCE ,,SNOBOL#D4 ,GIMPEL'S
GREATER WORK WAS ,,SPITBOL  THE COMPILED
IMPLEMENTATION THAT GAVE ,,SNOBOL#D
NEAR-NATIVE SPEED AND BECAME THE
REFERENCE IMPLEMENTATION FOR DECADES2
AFTER YEARS AS A COMMERCIAL ,CATSPAW
PRODUCT1 ,,SPITBOL WAS RELEASED AS FREE
SOFTWARE UNDER THE ,,GNU ,,GPL IN ,APRIL
#BJJI4.<CITE3 ,GIMPEL'S ,,SITBOL COURSE
IMPLEMENTATION "<#AIGB1 ,STEVENS
,INSTITUTE OF ,TECHNOLOGY"> AND
,,SPITBOL'S HISTORY THROUGH ITS .<#BJJI
,,GPL RELEASE4.>.>
,THE ECOSYSTEM PRODUCED ITS OWN ODD
CHILDREN4 ,SNOSTORM "<#AIGJ;S1 ,FRED
,SWARTZ1 ,UNIVERSITY OF ,MICHIGAN"> WAS
A PREPROCESSOR ADDING
STRUCTURED-PROGRAMMING CONSTRUCTS TO
,,SNOBOL FOR ,,MTS SITES4 ,SNOCONE
"<,ANDREW ,KOENIG1 #AIHE"> WENT FURTHER 
A SELF-CONTAINED BLOCK-STRUCTURED
LANGUAGE ON ,,SNOBOL SEMANTICS4
,MINNESOTA ,,SNOBOL#D BY ,VIKTORS
,BERSTIS REPRODUCED THE ,,IBM MAINFRAME
ORIGINAL MOST FAITHFULLY ON ,P,CS1 DOWN
TO ,FORTRAN-STYLE ,,FORMAT SUPPORT4
,CATSPAW1 ,INC4 SOLD COMMERCIAL PORTS
FOR ,,DOS1 ,MACINTOSH1 ,SUN AND
,,RS_/#FJJJ  ALL NOW FREE4 ,,GNU'S ,ADA
COMPILER CARRIES ,,GNAT4,SPITBOL1 THE
,,SPITBOL STRING SEMANTICS CALLABLE FROM
,ADA4 ,AND THE LANGUAGE RUNS TODAY3
,MACRO ,,SNOBOL#D BY ,PHIL ,BUDNE AND
THE ,,BSD-LICENSED ,,CSNOBOL#D PORT KEEP
THE ORIGINAL ,BELL ,LABS IMPLEMENTATION
COMPILING WHEREVER ;,C EXISTS4
.<FIGURE3 ,,,A DEC PDP,'-#AJ  THE
CLASSIC ,,SNOBOL#D MACHINE1 AND THE
PLATFORM OF THE ,,AI AND LANGUAGE
RESEARCH COMMUNITY "<PHOTO3 ,WIKIMEDIA
,COMMONS1 ,,CC ,,BY-,,SA">.>
,GRISWOLD GOES WEST3 ,,SL#E
,IN ,AUGUST #AIGA1 ,RALPH ,GRISWOLD LEFT
,BELL ,LABS FOR A PROFESSORSHIP AT THE
,UNIVERSITY OF ,ARIZONA1 BRINGING
,,SNOBOL#D WITH HIM  AND ,NATIONAL
,SCIENCE ,FOUNDATION SUPPORT TO KEEP
EVOLVING IT4 ,BY THEN THE LANGUAGE'S
DESIGN DEBTS WERE OBVIOUS4 ,ITS COLUMN
FORMAT AND LABEL-DRIVEN BRANCHING
BELONGED TO THE PUNCHED-CARD AGE2
STRUCTURED PROGRAMMING  IF_/THEN1 WHILE1
BLOCKS  HAD BECOME TABLE STAKES SINCE
,,ALGOL #FJ4 ,,SNOBOL#D'S SEMANTICS WERE
BRILLIANT AND ITS SYNTAX WAS DEAD4
,GRISWOLD'S FIRST ATTEMPT AT A
SUCCESSOR1 ,,SL#E "<8,,SNOBOL ,LANGUAGE
#E10 #AIGG">1 TRIED TO GRAFT THE
SUCCESS_/FAILURE MACHINERY ONTO
CONVENTIONAL CONTROL STRUCTURES4 ,HE
JUDGED THE RESULT A FAILURE  THE
MECHANISMS FOUGHT EACH OTHER4 ,IN #AIGG
HE WENT BACK TO FIRST PRINCIPLES AND SET
THE CONSTRAINTS FOR THE REAL SUCCESSOR3
KEEP ,,SNOBOL#D'S PHILOSOPHICAL AND
SEMANTIC BASIS2 TAKE ,,SL#E'S SYNTAX AND
ITS FEATURES2 DROP THE OVER-GENERAL
PROCEDURE MECHANISM4.<CITE3 ,RALPH ;,E4
,GRISWOLD AND ,DAVID ;,R4 ,HANSON1
.<8,AN ,OVERVIEW OF ,,SL#E01 ,,ACM
,,SIGPLAN ,NOTICES #AB3#D "<,APRIL
#AIGG">1 AND ,GRISWOLD @& ,GRISWOLD1
,THE ,ICON ,PROGRAMMING ,LANGUAGE1 #CRD
ED4  ON ,,SL#E'S LESSONS AND ,ICON'S
DESIGN CONSTRAINTS4.>.>
,THE NEW LANGUAGE WAS ,,SNOBOL#E FOR A
WHILE1 BUT IT HAD DRIFTED TOO FAR FROM
THE NAME4 ,THEY CONSIDERED ;S  AN HOMAGE
TO ;C1 A SIBLING TRIBUTE TO ;,C  AND
ABANDONED IT AS UNTYPESETTABLE4 ,IRVING
AND BARD WERE PROPOSED AND DROPPED2
8,,TL0  8,THE ,LANGUAGE0  WAS TOO COY4
,THEN ,XEROX ,,PARC'S
GRAPHICAL-INTERFACE WORK PUT THE WORD
ICON INTO THE COMPUTER LEXICON1 AND THE
NAME WAS CHOSEN  A DECISION ,GRISWOLD
LATER REGRETTED1 SINCE 8ICON0 HAD NO
GRAPHICAL FEATURES WHATEVER AND THE NAME
CONFUSED EVERYONE IT ATTRACTED4
,ICON
,ICON "<#AIGH"> IS THE IDEA OF ,,SNOBOL
REBUILT FOR THE STRUCTURED-PROGRAMMING
ERA3 ,PASCAL-FLAVORED SYNTAX "<3"71
PROCEDURE1 END"> WITH ,C'S BRACES AND A
MAIN PROCEDURE1 DYNAMICALLY TYPED1 NO
DECLARATIONS1 AUTOMATIC CONVERSION
BETWEEN NUMBERS AND STRINGS4 ,ON THE
SURFACE IT LOOKS LIKE A PLEASANT
SCRIPTING LANGUAGE OF ITS DECADE4
,UNDERNEATH IT RUNS THE STRANGEST AND
MOST ELEGANT CONTROL MODEL ANY
MAINSTREAM-ADJACENT LANGUAGE HAS EVER
SHIPPED4
,GOAL-DIRECTED PROGRAMMING
,IN CONVENTIONAL LANGUAGES A LOOKUP THAT
FINDS NOTHING RETURNS A SENTINEL  -#A1
NULL1 ,,EOF  AND THE PROGRAMMER WRITES
TESTS EVERYWHERE3 IF "<POS "7"7 -#A">1
WHILE "<"<;C "7 READ"<">"> 6"7 ,,EOF">4
,IN ,,SNOBOL1 AN OPERATION THAT COULDN'T
PRODUCE A RESULT FAILED1 AND THE
3;,S"<444">_/3;,F"<444"> TRANSFERS
STEERED EXECUTION BY IT4 ,ICON KEEPS THE
SEMANTIC  AN EXPRESSION SUCCEEDS WITH A
VALUE1 OR FAILS  AND WIRES IT INTO
ORDINARY STRUCTURED SYNTAX4 IF1 WHILE1
EVERY1 AND FRIENDS ARE ALL DRIVEN BY
SUCCESS AND FAILURE RATHER THAN BY
,BOOLEAN TESTS4
,THE PAYOFF IS CONCRETE4 ,FILE-COPYING
IN ,JAVA REQUIRES THE ,,EOF SENTINEL AND
AN EXPLICIT COMPARISON2 IN ,ICON IT IS3
WHILE WRITE"<READ"<">">
READ"<"> PRODUCES A LINE1 OR FAILS AT
END OF FILE2 FAILURE PROPAGATES THROUGH
WRITE INTO WHILE1 WHICH STOPS 
CORRECTLY1 SILENTLY1 BY DESIGN4
,COMPARISONS WORK THE SAME WAY3 A @< ;B
IS AN OPERATOR THAT SUCCEEDS AND RETURNS
;B1 OR FAILS  SO A @< ;B @< ;C DOES
EXACTLY WHAT IT LOOKS LIKE1 SINCE THE
FIRST COMPARISON HANDS ITS SECOND
OPERAND TO THE SECOND4 ,AND FAILURE IS
NOT AN EXCEPTION3 REACHING END OF FILE
IS AN EXPECTED OUTCOME1 NOT A THROWN
EMERGENCY4 ,ICON SIMPLY DECLINED THE
SENTINEL-AND-TEST INDUSTRY THAT OCCUPIED
EVERY OTHER LANGUAGE OF ITS GENERATION4
,BACKTRACKING COMPLETES THE PICTURE3
WHEN A BRANCH FAILS1 ,ICON CAN REWIND TO
AN EARLIER POINT AND TRY ANOTHER
ALTERNATIVE  AND REVERSIBLE ASSIGNMENT
"<@<-1 @<-@>"> EXISTS SO THAT VARIABLES
CHANGED INSIDE A FAILED COMPUTATION
RESTORE THEMSELVES1 A BUILT-IN ATOMICITY
THAT STRING SCANNING RELIES ON
CONSTANTLY3
_<   I @<- #AJ @&   ;J @<-
FIND"<PATTERN1 IN,STRING"> _>
,IF FIND FAILS1 THE BLOCK FAILS  AND I
@<- #AJ ROLLS ITSELF BACK1 LEAVING NO
PHANTOM ASSIGNMENT BEHIND4 ,IN A
LANGUAGE WITHOUT REVERSIBILITY1 A FAILED
PARSE ATTEMPT LEAVES THE CURSOR WHEREVER
THE ATTEMPT ABANDONED IT1 AND THE NEXT
ATTEMPT STARTS FROM A CORRUPT STATE4
,ICON'S SCAN EITHER COMMITS ITS CURSOR
MOVEMENT OR UNDOES IT1 WHICH IS EXACTLY
THE SEMANTICS A BACKTRACKING PARSER
WANTS AND EXACTLY WHAT EVERY
HAND-WRITTEN REGEX LOOP GETS SUBTLY
WRONG4
,ONE MORE CONTROL-FLOW SUBTLETY
SEPARATES ,ICON FROM EVERY NEIGHBOR3
EVERY AND WHILE LOOK ALIKE BUT ARE NOT4
WHILE ;E RE-EVALUATES ;E UNTIL IT FAILS 
ITS JOB IS REPETITION4 EVERY ;E DRIVES A
GENERATOR1 FETCHING THE NEXT RESULT ON
EACH PASS  ITS JOB IS ENUMERATION4 EVERY
WRITE"<I TO ;J"> AND WHILE ARE THE
DIFFERENCE BETWEEN 8GIVE ME EVERYTHING
THIS CAN PRODUCE0 AND 8KEEP DOING THIS
UNTIL IT STOPS WORKING40 ,THE
DISTINCTION MATTERS BECAUSE AN ,ICON
PROGRAMMER IS ALWAYS ASKING THE SAME
QUESTION3 DOES THIS EXPRESSION STILL
HAVE SOMETHING TO GIVE8
,GENERATORS
,IF GOAL-DIRECTED EXECUTION IS ,ICON'S
ENGINE1 THE GENERATOR IS ITS GREATEST
EXPORT4 ,IN ,ICON1 AN EXPRESSION DOESN'T
EVALUATE TO A VALUE  IT PRODUCES A
RESULT SEQUENCE3 EVERY VALUE IT COULD
PRODUCE1 YIELDED ONE AT A TIME TO
WHATEVER ASKED4 FIND"<8THE01 ;S">
DOESN'T RETURN THE FIRST POSITION OF
8THE0 AND STOP2 IT GENERATES POSITIONS 
#D1 THEN #BI  AND WHEN IT HAS NO MORE TO
GIVE1 IT FAILS4 ,THE EVERY CONSTRUCT
CONSUMES A SEQUENCE3
;S 3"7 8,ALL THE WORLD'S A STAGE4 ,AND
ALL THE MEN AND WOMEN MERELY PLAYERS0
EVERY WRITE"<FIND"<8THE01 ;S">">
,TWO LINES1 AND EVERY OCCURRENCE IS
PRINTED  NO INDEX VARIABLE1 NO -#A
SENTINEL1 NO LOOP BOOKKEEPING4 ,WHERE
OTHER LANGUAGES' INDEX,OF REQUIRES A
THREE-PARAMETER OVERLOAD AND A
HAND-ROLLED LOOP1 ,ICON'S GENERATOR
SIMPLY KEEPS ANSWERING UNTIL IT CAN'T4
,USER PROCEDURES BECOME GENERATORS WITH
SUSPEND1 WHICH YIELDS A VALUE AND PARKS
EXECUTION MID-PROCEDURE UNTIL RESUMPTION
A RETURN THAT DOESN'T DESTROY STATE3
PROCEDURE ,ITO,J"<I1 ;J">   WHILE I @<"7
;J DO _<     SUSPEND I     I "63"7 #A  
_>   FAIL END
,CALL ,ITO,J"<#A1 #E"> UNDER EVERY AND
IT YIELDS #A1 SUSPENDS2 RESUMES1 YIELDS
#B2 AND SO ON1 UNTIL FAIL ENDS THE
SEQUENCE4 ,ADD THE ALTERNATOR _\  WHICH
LOOKS LIKE OR BUT ACTUALLY GENERATES ITS
OPERANDS IN TURN  AND TO FOR INTEGER
RANGES1 AND ITERATION COLLAPSES TO
INTENT3
EVERY WRITE"<#A TO #AJ"> EVERY I 3"7
"<#A _\ #C _\ #D _\ #E _\ #AJ _\ #AA _\
#BC"> DO WRITE"<I"> EVERY ;X 3"7
,ITO,J"<#J1AJ"> @& ;X .0 #B "7"7 #J DO
WRITE"<;X">    _? EVENS ONLY
.<FIGURE3 ,HOW A GENERATOR DRIVES A
LOOP3 FIND"<"> YIELDS RESULTS ONE AT A
TIME2 EVERY CONSUMES THEM2 @&FAIL ENDS
THE LOOP CLEANLY.>
,IF THIS SOUNDS LIKE ,PYTHON'S YIELD1
THAT'S BECAUSE IT IS4 ,WHEN ,PYTHON
ADOPTED GENERATORS IN ,,PEP #BEE
"<#BJJA">1 ITS AUTHORS LISTED ,ICON
AMONG THE DIRECT INSPIRATIONS  THE
MECHANISM A GENERATION OF ,PYTHON
PROGRAMMERS KNOW AS LAZINESS WAS RUNNING
IN ,TUCSON TWO DECADES EARLIER4 ,THE
SAME ,,DNA SURFACES IN JQ'S STREAM
SEMANTICS AND THE ,ICON-DESCENDED
,GOALDI4 ,GENERATORS ARE NOW THE
STANDARD ANSWER TO 8ITERATE WITHOUT
MATERIALIZING02 ,ICON WAS THE PROOF OF
CONCEPT1 COMPLETE WITH THE COROUTINE
MACHINERY "<SUSPEND_/RESUME"> THAT
MODERN LANGUAGES STILL WRAP IN ITERATORS
AND ASYNC4.<CITE3 .<,,PEP #BEE NAMING
,ICON AS AN INSPIRATION FOR ,PYTHON'S
GENERATORS2 ,ICON'S SUSPEND_/RESUME AS
USER-LEVEL COROUTINES  ,GRISWOLD @&
,GRISWOLD #BJJB4.>.>
,STRING SCANNING
,ICON'S THIRD PILLAR IS THE STRING
SCANNING ENVIRONMENT3 ;S 8 EXPR BINDS ;S
AS THE SUBJECT FOR A BLOCK OF STRING
OPERATIONS1 WITH TWO IMPLICIT VARIABLES 
@&SUBJECT AND @&POS "<THE CURSOR"> 
DOING THE BOOKKEEPING THAT STRING
PARSING ALWAYS MAKES EXPLICIT4 ,INSIDE
81 FUNCTIONS LIKE TAB "<MOVE THE
CURSOR">1 MANY "<SKIP A RUN OF A
CHARACTER SET">1 UPTO "<FIND THE NEXT
MEMBER OF A SET">1 MATCH "<LITERAL
STRING AT CURSOR">1 AND POS "<TEST
CURSOR POSITION"> COMPOSE INTO PARSERS
OF STARTLING BREVITY4 ,WORDS FROM A
LINE3
;S 8 _<     WHILE NOT POS"<#J"> DO _<   
TAB"<MANY"<' '">">              _? SKIP
BLANKS         WORD 3"7 TAB"<UPTO"<' '">
_\ #J">  _? GRAB UP TO THE NEXT BLANK OR
END         WRITE"<WORD">     _> _>
,THE SAME MACHINERY THAT POWERED
,,SNOBOL#D PATTERNS  SUCCESS1 FAILURE1
CURSOR BACKTRACKING  IS ALL HERE1 JUST
RECAST IN FUNCTIONS ON AN IMPLICIT
SUBJECT INSTEAD OF A PATTERN DATATYPE4
,AN ,ICON STRING SCANNING BLOCK FOR A
REAL GRAMMAR "<THE CANONICAL EXAMPLE
PARSES DATE STRINGS LIKE 8,MON ,DEC #H0
WITH A TWENTY-LINE MATCHER"> IS THE
LINEAL DESCENDANT OF ,,SNOBOL'S
,,BNF-AS-PATTERN1 TRADED DOWN IN RAW
POWER FOR A LARGE GAIN IN READABILITY4
,THE PAYOFF SHOWS MOST CLEARLY IN THE
CLASSIC UTILITY PROGRAM  A
WORD-FREQUENCY COUNTER1 THE KIND OF
THING AWK PEOPLE WRITE TO SHOW OFF4 ,IN
,ICON THE WHOLE JOB IS TWENTY LINES AND
MOST OF IT IS THE SORTING3
PROCEDURE MAIN"<">     COUNTS 3"7
TABLE"<#J">                     _?
DEFAULT VALUE #J FOR NEW KEYS     EVERY
LINE 3"7 6@&INPUT DO _<             _?
GENERATOR READS THE STREAM         LINE
8 WHILE TAB"<UPTO"<@&LETTERS">"> DO _<  
COUNTS.<TAB"<MANY"<@&LETTERS">">.> "63"7
#A         _>     _>     PAIRS 3"7 .<.> 
EVERY WORD 3"7 KEY"<COUNTS"> DO
PUSH"<PAIRS1 .<WORD1 COUNTS.<WORD.>.>"> 
EVERY ;P 3"7 6PAIRS DO
WRITE"<RIGHT"<;P.<#B.>1#F">1 ,7  ,71
;P.<#A.>"> END
TABLE"<#J"> IS A MAP WHOSE MISSING KEYS
DEFAULT TO ZERO2 KEY GENERATES THE
TABLE'S KEYS2 THE SCANNING BLOCK WALKS
EACH LINE PULLING ALPHABETIC WORDS4 ,NO
REGEX LITERALS1 NO SPLIT_/JOIN CEREMONY 
THE SAME JOB THAT TAKES A PAGE IN MOST
LANGUAGES' STANDARD STYLE IS A PARAGRAPH
HERE1 AND THE PARAGRAPH IS STILL
READABLE4
,STRUCTURES AND STRINGS
,ICON'S COLLECTIONS WERE EQUALLY
PRESCIENT3 LISTS USABLE AS ARRAYS1
STACKS1 AND QUEUES2 TABLES  THE
ASSOCIATIVE ARRAYS ,MC,ILROY FORCED INTO
,,SNOBOL#D1 HERE A FIRST-CLASS CITIZEN2
SETS WITH UNION "6"61 INTERSECTION .*1
DIFFERENCE --2 AND CSETS"91 CHARACTER
SETS LIKE @&DIGITS1 @&LCASE1 AND
USER-DEFINED 'AEIOU'1 BUILT FOR THE
SCANNING OPERATIONS4 ,STRINGS ARE
INDEXABLE BETWEEN"9 CHARACTERS
"<POSITION #A IS BEFORE THE FIRST
CHARACTER1 POSITION #J AFTER THE LAST">1
SLICEABLE FROM EITHER END1 AND MUTABLE
THROUGH THEIR SUBSCRIPTS  ;S.<#B.> 3"7
8#ABC0 INSERTS INTO THE MIDDLE OF 8ABC04
,EVERYTHING ITERABLE IS A GENERATOR1
DOWN TO 6LIST PRODUCING A LIST'S
ELEMENTS AND 68,HELLO0 PRODUCING A
STRING'S CHARACTERS4 ,EVEN @&INPUT 
STANDARD INPUT  IS A GENERATOR3 EVERY
PUSH"<LINES1 6@&INPUT">.* READS A WHOLE
STREAM INTO A LIST IN ONE EXPRESSION4
,FOR COMPLETENESS1 ,ICON ALSO SHIPPED
CO-EXPRESSIONS  FIRST-CLASS COROUTINE
OBJECTS THAT CAPTURE A SUSPENDED
COMPUTATION AND CAN BE RESUMED
EXPLICITLY WITH @A4 ,GENERATORS GET
THEIR VALUES FOR FREE1 IN LEXICAL ORDER2
A CO-EXPRESSION GETS THEM ON DEMAND1
FROM WHEREVER YOU LIKE1 MAKING IT THE
GENERAL MECHANISM BENEATH SUSPEND AND
THE DIRECT ANCESTOR OF THE
COROUTINE_/YIELD MACHINERY MODERN
LANGUAGES EXPOSE DIRECTLY4 ,IT IS ONE
MORE CASE OF ,ICON QUIETLY SHIPPING IN
#AIGH WHAT OTHER LANGUAGES WOULD SPEND
THE NEXT FOUR DECADES REDISCOVERING
PIECEMEAL  FIRST AS ITERATORS1 THEN AS
GENERATORS1 THEN AS ASYNC4
,,SNOBOL#D AND ,ICON SIDE BY SIDE
,,SNOBOL#D "<#AIFG">  ,ICON "<#AIGH">  
,SURFACE  ,COLUMN-FORMAT1 LABELS AND
3,S_/3;,F TRANSFERS 
,,ALGOL_/,PASCAL-FLAVORED BLOCKS1
PROCEDURE1 3"7   ,CONTROL MODEL 
SUCCESS_/FAILURE BRANCHING 
SUCCESS_/FAILURE EVERYWHERE 
GOAL-DIRECTED   ,PATTERN FACILITY 
PATTERNS AS FIRST-CLASS DATA1 FULL
CONTEXT-FREE POWER  STRING SCANNING3 81
@&SUBJECT1 @&POS1 TAB_/MANY_/UPTO  
,ITERATION  MANUAL LOOPS VIA TRANSFERS 
GENERATORS  EVERY1 TO1   1 61 SUSPEND  
,DATA  STRINGS1 NUMBERS1 ARRAYS1 TABLES1
,,DATA RECORDS  LISTS1 TABLES1 SETS1
CSETS1 RECORDS1 CO-EXPRESSIONS   ,THE
TRADE  MAXIMUM EXPRESSIVE POWER  MOST OF
THE POWER1 DRESSED FOR THE
STRUCTURED-PROGRAMMING ERA ,THE TWO ARE
NOT RIVALS BUT STAGES OF ONE IDEA3
,,SNOBOL#D PROVED THAT MATCHING AND
FAILURE COULD BE A PROGRAMMING LANGUAGE2
,ICON PROVED THAT IDEA COULD WEAR THE
CLOTHES OF A NORMAL ONE4
,CRITICISMS
,AN HONEST ACCOUNT HAS TO INCLUDE WHAT
WENT WRONG4 ,LAURENCE ,TRATT'S #BJAJ
ANALYSIS OF ,ICON'S DESIGN IS THE
STANDARD CRITICAL TEXT1 AND ITS TWO MAIN
FINDINGS ARE INSTRUCTIVE4.<CITE3
,LAURENCE ,TRATT1 .<8,EXPERIENCES WITH
AN ,ICON-LIKE EXPRESSION EVALUATION
SYSTEM0 "<#BJAJ">  THE STANDARD DESIGN
CRITIQUE4.>.>
,FIRST1 THE DEFAULT-FAIL CONVENTION3 A
PROCEDURE THAT RUNS OFF ITS END RETURNS
@&FAIL4 ,ELEGANT FOR GENERATORS1 IT
MAKES ;X 3"7 ;F"<-#A"> A SILENT NO-OP 
;X KEEPS ITS OLD VALUE1 NO WARNING  AND
,TRATT FOUND THE VAST MAJORITY OF REAL
,ICON PROCEDURES ARE NOT GENERATORS1 SO
THE LANGUAGE'S DEFAULT BEHAVIOR
OPTIMIZES FOR THE MINORITY CASE WHILE
CREATING A SUBTLE TRAP IN THE MAJORITY4
,SECOND1 THE ABSENCE OF ,BOOLEAN LOGIC
CREATES EDGE CASES OF ITS OWN3 IF ;C
THEN 444 SUCCEEDS EVEN WHEN ;C WAS NEVER
ASSIGNED1 BECAUSE AN UNASSIGNED
VARIABLE'S VALUE "<@&NULL"> IS STILL A
VALUE  SO THE TEST MUST BE WRITTEN IF
_/C THEN 444 OR ;C "7"7"7 @&NULL4 ,ICON
TRADED ,BOOLEAN COMPLEXITY FOR FAILURE
PROPAGATION1 AND MOSTLY WON  BUT NOT
EVERYWHERE1 AND NOT FREE4
,THE FAIR SUMMARY IS THE ONE ,ICON'S OWN
COMMUNITY REACHES3 FOR THE DOMAIN IT WAS
BUILT FOR  STRINGS1 SCANNING1 SEARCH 
GOAL-DIRECTED CODE IS SHORTER1 CLEARER1
AND HARDER TO GET WRONG THAN ANYTHING
BEFORE OR SINCE4 ,FOR GENERAL-PURPOSE
PROGRAMMING1 THE SAME RULES OCCASIONALLY
SURPRISE4 ,THE IDEA WAS TOO GOOD FOR ITS
MEDIUM4
,UNICON AND TODAY
,ICON'S LINEAGE CONTINUES4 ,UNICON
"<FROM ,IDOL1 THE #AIIF OBJECT-ORIENTED
EXTENSION"> ADDS OBJECTS1 NETWORKING1
DATABASES1 AND CONCURRENCY TO THE CORE
LANGUAGE AND REMAINS ACTIVELY DEVELOPED4
,THE REFERENCE ,ICON IMPLEMENTATION
ITSELF IS STILL MAINTAINED  RELEASE
#I4E4BE;A SHIPPED IN ,SEPTEMBER #BJBE1
FORTY-SEVEN YEARS AFTER THE LANGUAGE WAS
DESIGNED4 ,,SNOBOL#D RUNS WHEREVER
,,CSNOBOL#D COMPILES2 ,GRISWOLD'S
IMPLEMENTATION AND BOOKS REMAIN
AVAILABLE2 AND THE ,UNIVERSITY OF
,ARIZONA KEEPS THE ,ICON PROJECT PAGES
THAT THE LANGUAGE'S RESEARCHERS BUILT4
,THESE LANGUAGES ARE NOT SPECIMENS UNDER
GLASS4 ,THEY COMPILE1 THEY RUN1 AND
THEIR MAINTAINERS STILL SHIP RELEASES4
,RUNNING IT TODAY
,EVERY IMPLEMENTATION MENTIONED HERE IS
FREE3
,,SNOBOL#D  ,,CSNOBOL#D "<,,BSD-LICENSED
PORT OF THE ,BELL ,LABS ORIGINAL1 BUILDS
ANYWHERE ;,C EXISTS">1 ,MACRO ,,SNOBOL#D
"<,PHIL ,BUDNE'S PORTABLE ;,C
IMPLEMENTATION">1 ,,SPITBOL "<,,GPL
SINCE #BJJI1 THE FASTEST BY FAR">1 AND
THE FAITHFUL ,MINNESOTA ,,SNOBOL#D"9 FOR
,,PC-ERA FIDELITY4 ,THE CLEARINGHOUSE IS
SNOBOL#D4ORG2 THE PRESERVATION MIRROR IS
REGRESSIVE4ORG_/SNOBOL#D4  ,ICON  THE
REFERENCE IMPLEMENTATION FROM THE
,UNIVERSITY OF ,ARIZONA ,ICON PROJECT
"<WWW4CS4ARIZONA4EDU_/ICON">1 PLUS ,JCON
FOR THE ,,JVM4 ,THE ,GRISWOLDS' ,THE
,ICON ,PROGRAMMING ,LANGUAGE"9 "<#CRD
ED41 #BJJB"> IS THE BOOK1 AND THE
,ARIZONA SITE HOSTS THE DOCUMENTATION
SET4 "9 ,UNICON  UNICON4ORG1 FOR ,ICON
WITH OBJECTS1 ,,POSIX FACILITIES1 AND A
STANDARD LIBRARY THE ORIGINAL NEVER
NEEDED4
,THE CLASSIC TEXTS REMAIN FINDABLE3 THE
8GREEN BOOK0  ,GRISWOLD1 ,POAGE @&
,POLONSKY1 ,THE ,,SNOBOL#D ,PROGRAMMING
,LANGUAGE "<#AIFH">  ,GRISWOLD'S ,THE
,MACRO ,IMPLEMENTATION OF ,,SNOBOL#D
"<#AIGB"> FOR THE VIRTUAL-MACHINE
INTERNALS1 ,GIMPEL'S ,ALGORITHMS IN
,,SNOBOL#D "<#AIGF">1 AND ,HOCKEY'S
,,SNOBOL ,PROGRAMMING FOR THE
,HUMANITIES "<#AIHE"> FOR THE PERIOD'S
APPLIED TRADITION4 ,GRISWOLD'S OWN 8,A
,HISTORY OF THE ,,SNOBOL ,PROGRAMMING
,LANGUAGES0 "<#AIGH"> AND THE ,,HOPL
VOLUME CHAPTER ARE THE PRIMARY-SOURCE
HISTORY  THIS ARTICLE LEANS ON THEM
THROUGHOUT4
,LANGUAGE HISTORY3 WHAT THE LINE TAUGHT
US
,PLACED END TO END1 THE ,,SNOBOL,ICON
STORY IS A COMPRESSED HISTORY OF HOW
PROGRAMMING-LANGUAGE IDEAS ACTUALLY
TRAVEL4 ,A CONCEPT APPEARS "<,,COMIT'S
REWRITE RULES">1 IS PERFECTED IN A FORM
THE MAINSTREAM CAN'T ABSORB
"<,,SNOBOL#D'S PATTERN DATATYPE ON A
#AIFG MAINFRAME">1 IS REDISCOVERED IN
DILUTED FORM BY FASHIONABLE SUCCESSORS
"<,,AWK'S PATTERNS1 ,PERL'S REGEXES">1
AND IS FINALLY RE-EMBEDDED SO QUIETLY
THAT ITS USERS NEVER LEARN WHERE IT CAME
FROM "<,PYTHON'S YIELD1 JQ'S STREAMS1
EVERY PARSER-COMBINATOR LIBRARY ON
,EARTH">4
,THERE IS A SUBTLER LESSON IN THE
LINEAGE1 TOO3 IDEAS PERSIST BETTER THAN
IMPLEMENTATIONS4 ,,SNOBOL#D THE ARTIFACT
IS A CURIOSITY  COLUMN-FORMAT1
MAINFRAME-BOUND1 ITS IDIOMS EXTINCT4
,BUT THE IDEA THE ARTIFACT CARRIED
TURNED OUT TO BE LOAD-BEARING4 ,IT
SURVIVED A SYNTAX CHANGE "<,ICON">1
SURVIVED BEING RENAMED "<GENERATORS">1
SURVIVED BEING DILUTED "<REGEX">1 AND
SURFACED AGAIN EVERY TIME THE INDUSTRY
REDISCOVERED THAT TEXT IS MOST OF WHAT
COMPUTERS ACTUALLY PROCESS4 ,WHEN ,LUA'S
DESIGNERS WROTE THEIR ,,HOPL HISTORY1
THEY LISTED ,,SNOBOL AMONG THEIR
LANGUAGE'S INFLUENCES  THE PATTERN
TRADITION REACHING EVEN THE
EMBEDDABLE-SCRIPTING NICHE BY WAY OF ITS
REPUTATION4 ,WHEN ,STEPHEN ,BOURNE
NEEDED A ,UNIX SHELL SCRIPTING LANGUAGE
IN THE SAME ,BELL ,LABS BUILDING WHERE
,,SNOBOL WAS MADE1 THE RESULT1 BS1
BORROWED ,,SNOBOL-FLAVORED FEATURES
OUTRIGHT4 ,THE FAMILY TOUCHES NEARLY
EVERY STRING-HANDLING IDIOM IN DAILY
USE4
,THREE OF THE MODERN PROGRAMMER'S DAILY
TOOLS DESCEND DIRECTLY FROM THIS FAMILY3
"9 ,PATTERN MATCHING  ,,SNOBOL#D DEFINED
THE PROBLEM SPACE REGULAR EXPRESSIONS
STILL OCCUPY1 AND ITS CONTEXT-FREE POWER
REMAINS BEYOND STOCK REGEX FORTY-FIVE
YEARS LATER4 "9 ,GENERATORS  ,ICON'S
SUSPEND_/RESUME IS ,PYTHON'S YIELD1 AND
THE LAZY SEQUENCE IS NOW HOW THE
INDUSTRY THINKS ABOUT ITERATION4 "9
,GOAL-DIRECTED EVALUATION 
SUCCESS_/FAILURE AS A CONTROL PRIMITIVE
PREVIEWS TODAY'S RESULT TYPES AND
EARLY-RETURN STYLES "<,RESULT IN ,RUST1
ERR "7"7 NIL IN ,GO">  THE SAME
INSTINCT3 MAKE FAILURE A VALUE1 AND LET
THE PROGRAM STEER BY IT4
,THE LANGUAGES THEMSELVES1 MEANWHILE1
SIMPLY PERSISTED  MAINTAINED1 PORTED1
FREE1 AND STILL TAUGHT TO ANYONE WILLING
TO LOOK BACK4 ,TEXT DIDN'T STOP NEEDING
PROCESSING IN #AIFG1 AND THE TOOLS ,BELL
,LABS AND ,TUCSON BUILT FOR IT HAVE
NEVER ACTUALLY BEEN IMPROVED UPON AT THE
THINGS THEY WERE BUILT FOR4
,AND ONE MORE THING PERSISTS3 THE RECORD
ITSELF4 ,GRISWOLD WROTE HIS HISTORY IN
#AIGH1 WHILE THE STORY WAS STILL WARM4
,THE GREEN BOOK IS STILL READABLE4 ,THE
,,SPITBOL SOURCE STILL COMPILES4 ,THE
,ARIZONA ,ICON PAGES STILL SERVE4
,,SNOBOL AND ,ICON ARE AMONG THE
BEST-PRESERVED LANGUAGES OF THEIR
GENERATION  DOCUMENTED BY THEIR OWN
AUTHORS1 IN THEIR OWN WORDS1 WITH THE
SOURCE STILL RUNNABLE4 ,THAT IS WHAT
PRESERVATION LOOKS LIKE WHEN IT WORKS4
,KNOWLEDGE IS ONLY EVER LOST WHEN THE
WORLD STOPS LOOKING  AND PAGES LIKE THIS
ONE EXIST TO MAKE SURE IT DOESN'T4
,SEE ALSO
"9 ,,FORTRAN  THE NUMERIC WORLD ,,SNOBOL
ANSWERED TO "9 ,ADA "<PROGRAMMING
LANGUAGE">  ,,GNAT4,SPITBOL CARRIES
,,SNOBOL#D'S SEMANTICS INTO ,ADA "9
,HISTORY OF ,PROGRAMMING  THE LARGER MAP
THIS LINEAGE BELONGS TO "9 ,CHEVALIER DE
,SAINT-,GEORGES  ON PRESERVING PEOPLE
HISTORY NEARLY LOST2 LANGUAGES DESERVE
THE SAME "9 ,,REBOL  THE MESSAGING
BRANCH OF THE SAME DATA-IS-CODE
TRADITION