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- <meta name="author" content="Ferruccio Guidi" />
- <meta name="description" content="\lambda\delta home page: Open Symbolic Notation" />
- <title>\lambda\delta home page: Open Symbolic Notation</title>
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- <a href="http://lambdadelta.info/osn/">
- <img class="w3c" alt="[Open Symbolic Notation logo]" title="OSN: Open Symbolic Notation" src="http://lambdadelta.info/images/osn_label.png" />
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- </div>
- <div class="head1">Open Symbolic Notation</div>
- <div class="spacer">
- <img class="rule" alt="[Spacer]" title="\lambda\delta rainbow rule" src="http://lambdadelta.info/images/rainbow.png" />
- </div>
- <div xmlns:ld="http://lambdadelta.info/" class="text">
- Open Symbolic Notation, abbreviated OSN,
- is an easy and flexible data-interchange text format
- intended for the lightweight representation of
- generic abstract syntax trees in the domain of formal languages.
- In order to meet these design goals, OSN pursues the following features.
- </div>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="red-mark">
- <span class="alpha">
- <a href="https://en.wikipedia.org/wiki/S-expression">Symbolic expressions</a>
- based on widely accepted syntactical conventions
- provide for a <span class="emph ">lightweight</span> and <span class="emph ">generic</span> grammar,
- which is both <span class="emph ">easy for machines to process</span>,
- and <span class="emph ">easy for humans to understand</span>.
- As a mean to support <span class="emph ">efficient</span> information processing,
- OSN aims at an economic representation of data
- contrary to <a href="http://www.w3.org/TR/2008/REC-xml-20081126/#sec-origin-goals">XML design goal 10</a>.
- Compared to other data-interchange formats based on symbolic expressions,
- like <a href="http://people.csail.mit.edu/rivest/Sexp.txt">canonical symbolic expressions</a>,
- representing arbitrary data in binary format is a secondary concern in the design of OSN,
- as well as the support for canonicalization.
- Apparently, these features fall outside the scope of OSN,
- which targets the data structures of <span class="emph ">formal languages</span>.
- </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="blue-mark">
- <span class="alpha">
- Optionally <a href="https://en.wikipedia.org/wiki/Namespace">qualified</a> symbolic expressions
- allow OSN texts to mix data from different domains preserving their own semantics
- because name conflicts can be avoided.
- As a consequence OSN documents are <span class="emph ">easy to extend</span> in that
- domain-specific OSN applications can work as expected even if
- data from different domains is added to the text they process.
- </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="green-mark">
- <span class="alpha">
- The <a href="https://en.wikipedia.org/wiki/ASCII">US-ASCII</a> character set,
- extended to <a href="http://www.utf-8.com/">UTF-8</a> in
- free-form text strings for the convenience of human readers,
- makes OSN documents <span class="emph ">easy to visualize and transport</span> over communication media.
- OSN design aims at supporting <span class="emph ">application-independent</span> standard encodings.
- </span>
- </li>
- </ul>
- <div xmlns:ld="http://lambdadelta.info/" class="head2dx" id="grammar">Grammar <img class="icon37" alt="[butterfly]" title="\lambda\delta butterfly" src="http://lambdadelta.info/images/b6.png" />
- </div>
- <div xmlns:ld="http://lambdadelta.info/" class="text">
- An OSN text uses the <a href="http://www.utf-8.com/">UTF-8</a> character set
- and contains the next seven tokens that we define in a very common EBNF variant.
- Characters not starting a token are not allowed.
- The ones in the range U+0021 ... U+007E are ! # $ % & * / ? @ \ ^ | ~
- and are available for extensions of OSN.
- </div>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token can represent the identifiers and the numerical constants of most programming languages:
- <br />
- <span class="emph ebnf">symbol = 1 * symbol-char ; <br />symbol-char = '+' | '-' | '.' | '0' | ... | '9' | 'A' | ... | 'Z' | '_' | '`' | 'a' | ... | 'z' ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token contains free-form text with commonly accepted escape sequences:
- <br />
- <span class="emph ebnf">string = '"' , * ( string-char | "'" | '\' escape ) , '"' ; <br />string-char = ( #0 | ... | #10FFFF ) - ( #0 | ... | #1F | "'" | '\' | '"' | #7F ) ; <br />escape = 1 * space | '"' | "'" | '(' | ')' | '0' | '\' | 'a' | 'b' | 'e' | 'f' | 'n' | 'r' | 't' | ( 'u' , 4 * 4 hex ) | 'v' | ( 'x' , 2 * 2 hex ) ; <br />space = #9 | ... | #D | #20 ; <br />hex = '0' | ... | '9' | 'A' | ... | 'F' | 'a' | ... | 'f' ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token is a widely used alternative of the former token:
- <br />
- <span class="emph ebnf">string-alt = "'" , * ( string-char | '"' | '\' escape ) , "'" ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token separates the qualifiers of a symbolic expression:
- <br />
- <span class="emph ebnf">sep = ':' ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token starts a compound symbolic expression:
- <br />
- <span class="emph ebnf">open = '(' | '<' | '[' | '{' ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token ends a compound symbolic expression:
- <br />
- <span class="emph ebnf">close = ')' | '>' | ']' | '}' ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- This token is ignored and separates the other tokens:
- <br />
- <span class="emph ebnf">gap = space | ',' | ';' | '=' ; </span>
- </li>
- </ul>
- <div xmlns:ld="http://lambdadelta.info/" class="text">
- The grammar of OSN is very liberal by design.
- Spaces of the form <span class="emph ebnf">1 * gap </span> can appear between any pair of tokens.
- </div>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- An OSN text:
- <br />
- <span class="emph ebnf">text = * q-expr ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- A qualified symbolic expression:
- <br />
- <span class="emph ebnf">q-expr = * ( symbol , 1 * sep ) , expr ; </span>
- </li>
- </ul>
- <ul xmlns:ld="http://lambdadelta.info/">
- <li class="">
- An unqualified symbolic expression:
- <br />
- <span class="emph ebnf">expr = symbol | string | string-alt | ( open , text , close ) ; </span>
- </li>
- </ul>
- <div xmlns:ld="http://lambdadelta.info/" class="head2dx" id="semantics">Semantics <img class="icon37" alt="[butterfly]" title="\lambda\delta butterfly" src="http://lambdadelta.info/images/b1.png" />
- </div>
- <div xmlns:ld="http://lambdadelta.info/" class="text">
- Forthcoming ...
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- <!--
- morover, the escape sequences \x <two hexadecimal digits> and \u <four hexadecimal digits>
- allow to specify a character by its code point <newline/>
- finally the escape sequences \( for U+0002 and \) for U+0003 are available
--->
- <div xmlns:ld="http://lambdadelta.info/" class="head2dx" id="implementation">Implementation <img class="icon37" alt="[butterfly]" title="\lambda\delta butterfly" src="http://lambdadelta.info/images/b5.png" />
- </div>
- <div xmlns:ld="http://lambdadelta.info/" class="text">
- Forthcoming ...
- </div>
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- <img class="rule" alt="[Spacer]" title="\lambda\delta rainbow rule" src="http://lambdadelta.info/images/rainbow.png" />
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- <div xmlns:ld="http://lambdadelta.info/" class="spacer">Last update: Fri, 24 Nov 2017 21:00:00 +0100</div>
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projects / helm.git / blobdiff