Editing SNOBOL (section)

{{Short description|Text-string-oriented programming language}}
{{About|the programming language|the cleaning product|SnoBol (cleaner)}}

{{Infobox programming language
| name                   = SNOBOL
| paradigm               = [[imperative programming|Imperative]], [[Procedural programming|procedural]], [[unstructured programming|unstructured]]
| year                   = {{Start date and age|1962}}
| designer               = [[David J. Farber]], [[Ralph Griswold]] and [[Ivan P. Polonsky]]
| developer              = David J. Farber, Ralph E. Griswold, Ivan P. Polonsky, and [[Bell Labs]]
| latest release version = SNOBOL4
| latest release date    = {{Start date and age|1967}}
| implementations        = SNOBOL, [[SPITBOL]]
| influenced by          = [[COMIT]]
| influenced             = [[AWK]], SL5, [[Icon (programming language)|Icon]], [[bs (programming language)|bs]], [[Lua (programming language)|Lua]]<ref>{{Citation |last1=Ierusalimschy |first1=Roberto |last2=de Figueiredo |first2=Luiz Henrique |last3=Celes |first3=Waldemar |title=Proceedings of the third ACM SIGPLAN conference on History of programming languages |chapter=The evolution of Lua | date=2007 |url=https://www.lua.org/doc/hopl.pdf |volume= |issue= |pages=26 |doi=10.1145/1238844.1238846 |isbn=9781595937667 |s2cid=475143 |access-date=}}</ref>
| website                = https://www.regressive.org/snobol4/
}}

'''SNOBOL''' ("StriNg Oriented and symBOlic Language") is a series of [[programming language]]s developed between 1962 and 1967 at [[AT&T Corporation|AT&T]] [[Bell Laboratories]] by [[David J. Farber]], [[Ralph Griswold]] and Ivan P. Polonsky, culminating in SNOBOL4. It was one of a number of [[String (computer science)|text-string]]-oriented languages developed during the 1950s and 1960s; others included [[COMIT]] and [[TRAC (programming language)|TRAC]]. Despite the similar name, it is entirely unlike [[COBOL]].

SNOBOL4 stands apart from most programming languages of its era by having patterns as a [[first-class object|first-class data type]], a data type whose values can be manipulated in all ways permitted to any other data type in the programming language, and by providing operators for pattern [[concatenation]] and [[alternation (formal language theory)|alternation]]. SNOBOL4 patterns are a type of object and admit various manipulations, much like later [[object-oriented language]]s such as [[JavaScript]] whose patterns are known as [[regular expression]]s. In addition SNOBOL4 strings generated during execution can be treated as programs and either interpreted or compiled and executed (as in the [[eval]] function of other languages).

SNOBOL4 was quite widely taught in larger U.S. universities in the late 1960s and early 1970s and was widely used in the 1970s and 1980s as a text manipulation language in the [[humanities]].

In the 1980s and 1990s, its use faded as newer languages such as [[AWK]] and [[Perl]] made string manipulation by means of [[regular expression]]s fashionable. SNOBOL4 patterns include a way to express [[Backus–Naur Form|BNF]] grammars, which are equivalent to [[context-free grammar]]s and more powerful than regular expressions.<ref>{{cite journal |author=Gimpel, J. F. |title=A theory of discrete patterns and their implementation in SNOBOL4 |journal=Communications of the ACM |volume=16 |issue=2 |date=February 1973 |pages=91–100 |doi=10.1145/361952.361960|s2cid=17059429 |doi-access=free }}</ref> 
The "regular expressions" in current versions of AWK and Perl are in fact extensions of regular expressions in the [[Regular language|traditional sense]], but regular expressions, unlike SNOBOL4 patterns, are not recursive, which gives a distinct computational advantage to SNOBOL4 patterns.<ref>{{cite web|url=http://www.drdobbs.com/architecture-and-design/programs-that-transform-their-own-source/228701469 |title=Dr. Dobb's: Programs That Transform Their Own Source Code; or: the Snobol Foot Joke |publisher=Dobbscodetalk.com |access-date=2011-12-04}}</ref> (Recursive expressions did appear in [[Perl 5 version history|Perl 5.10]], though, released in December 2007.<ref>{{cite web|author=Contact details |url=http://perldoc.perl.org/5.10.0/perlre.html#Extended-Patterns |title=perlre |publisher=perldoc.perl.org |access-date=2011-12-04}}</ref><ref>{{cite web|url=http://www.rexegg.com/regex-recursion.html|title=Recursive Regex Tutorial|access-date=2017-03-19}}</ref>)

The later SL5 (1977)<ref>{{cite journal |first1=Ralph E. |last1=Griswold |first2=David R. |last2=Hanson |title=An Overview of SL5 |journal=ACM SIGPLAN Notices |volume=12 |issue=4 |pages=40–50 |date=April 1977 |doi=10.1145/954654.954658 |s2cid=38692673 |url=|doi-access=free }}</ref> and [[Icon (programming language)|Icon]] (1978) languages were designed by Griswold to combine the backtracking of SNOBOL4 pattern matching with more standard [[ALGOL]]-like structuring.