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S/SL programming language
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<p>The Syntax/Semantic Language (S/SL) is an executable <a href="/facts/High-level_programming_language/smjECUhx">high level</a> <a href="/facts/Specification_language/vqNInfdh">specification language</a> for <a href="/facts/Recursive_descent_parser/ARhcuAv1">recursive descent parsers</a>, semantic analyzers and code generators developed by <a href="/facts/James_Cordy/0a9AhkBk">James Cordy</a>, <a href="/facts/Ric_Holt/xnfcaVbF">Ric Holt</a> and David Wortman at the <a href="/facts/University_of_Toronto/FpGjQNm9">University of Toronto</a> in 1980. </p><p>S/SL is a small <a href="/facts/Programming_language/cWTYbgWa">programming language</a> that supports cheap <a href="/facts/Recursion/CxSKxJoW">recursion</a> and defines input, output, and error token names (& values), semantic mechanisms (class interfaces whose methods are really escapes to routines in a host programming language but allow good abstraction in the <a href="/facts/Pseudocode/XgN19duK">pseudocode</a>) and a pseudocode program that defines the <a href="/facts/Syntax/6PxSV98p">syntax</a> of the input language by the token stream the program accepts. Alternation, control flow and one-symbol look-ahead constructs are part of the language. </p><p>The S/SL processor <a href="/facts/Compiler/WNfCDFJe">compiles</a> this pseudocode into a table (byte-codes) that is interpreted by the S/SL table-walker (<a href="/facts/Interpreter_(computing)/JB85fbyb">interpreter</a>). The pseudocode language processes the input language in <a href="/facts/LL(1)/ot65DwYm">LL(1)</a> <a href="/facts/Recursive_descent/ARhcuAv1">recursive descent</a> style but extensions allow it to process any <a href="/facts/LR_parser/bpMod8K0">LR(k)</a> language relatively easily. S/SL is designed to provide excellent syntax error recovery and repair. It is more powerful and transparent than <a href="/facts/Yacc/sXp5I7Tw">Yacc</a> but can be slower. </p><p>S/SL's "semantic mechanisms" extend its capabilities to all phases of compiling, and it has been used to implement all phases of compilation, including <a href="/facts/Lexical_analysis/T1JYWpIf">scanners</a>, <a href="/facts/Parser/nRKB01S3">parsers</a>, <a href="/facts/Semantic_analysis_(compilers)/uVGz8wBw">semantic analyzers</a>, <a href="/facts/Code_generation_(compiler)/6Ce9gjPs">code generators</a> and <a href="/facts/Virtual_machine/BLevU3sx">virtual machine</a> interpreters in multi-pass language processors. </p><p>S/SL has been used to implement production commercial <a href="/facts/Compiler/WNfCDFJe">compilers</a> for languages such as <a href="/facts/PL%2fI/469mVYgd">PL/I</a>, <a href="/facts/Euclid_(programming_language)/juXVgqbg">Euclid</a>, <a href="/facts/Turing_(programming_language)/Dskr312J">Turing</a>, <a href="/facts/Ada_(programming_language)/Y2yHel4l">Ada</a>, and <a href="/facts/COBOL/wVnhqs0k">COBOL</a>, as well as interpreters, command processors, and domain specific languages of many kinds. It is the primary technology used in <a href="/facts/IBM/QszA7nwd">IBM</a>'s ILE/400 COBOL compiler, and the <a href="/facts/ZMailer/cbqrrh6c">ZMailer</a> <a href="/facts/Mail_transfer_agent/9SJG5sbb">mail transfer agent</a> uses S/SL for defining both its mail router processing language and its RFC 822 email address validation. </p>