Moved spec

doc/spec/03.01.lexical_structure.tex

@@ -1,113 +0,0 @@
-\section{Lexical Structure}
-\label{sec:lexical_structure}
-
-The character set for the language is \textsc{ASCII}, case-sensitive. In the following lexical description we will use
-the GNU Regexp syntax~\cite{GNULib} in lexical definitions.
-
-\subsection{Whitespaces and Comments}
-
-Whitespaces and comments are \textsc{ASCII} sequences which serve as delimiters for other tokens but otherwise are
-ignored.
-
-The following characters are treated as whitespaces:
-
-\begin{itemize}
-\item blank character "\texttt{ }";
-\item newline character "\texttt{\textbackslash n}";
-\item carriage return character "\texttt{\textbackslash r}";
-\item tabulation character "\texttt{\textbackslash t}".
-\end{itemize}
-
-Additionally, two kinds of comments are recognized:
-
-\begin{itemize}
-\item end-of-line comment "\texttt{--}" escapes the rest of the line, including itself;
-\item block comment "\texttt{(*} ... \texttt{*)}" escapes all the text between
-  "\texttt{(*}" and "\texttt{*)}".
-\end{itemize}
-
-There is a number of specific cases which have to be considered explicitly.
-
-First, block comments can be properly nested. Then, the occurrences of comment symbols inside string literals (see below) are not
-considered as comments.
-
-End-of-line comment encountered \emph{outside} of a block comment escapes block comment symbols:
-
-\begin{lstlisting}
-    -- the following symbols are not considered as a block comment: (*
-    -- same here: *)
-\end{lstlisting}
-
-Similarly, an end-of-line comment encountered inside a block comment is escaped:
-
-\begin{lstlisting}
-    (* Block comment starts here ...
-       -- and ends here: *)
-\end{lstlisting}
-
-\subsection{Identifiers and Constants}
-
-The language distinguishes identifiers, signed decimal literals, string and character literals (see Fig.~\ref{idents_and_consts}). There are
-two kinds of identifiers: those beginning with uppercase characters (\token{UIDENT}) and lowercase characters (\token{LIDENT}).
-
-String literals cannot span multiple lines; a blockquote character (") inside a string literal has to be doubled to prevent from
-being considered as this literal's delimiter.
-
-Character literals as a rule are comprised of a single \textsc{ASCII} character; if this character is a quote (') it has to be doubled. Additionally
-two-character abbreviations "\textbackslash t" and "\textbackslash n" are recognized and converted into a single-character representation.
-
-\begin{figure}[t]
-  \[
-  \begin{array}{rcl}
-    \token{UIDENT} & = &\mbox{\texttt{[A-Z][a-zA-Z\_0-9]*}}\\
-    \token{LIDENT} & = &\mbox{\texttt{[a-z][a-zA-Z\_0-9]*}}\\
-    \token{DECIMAL}& = &\mbox{\texttt{-?[0-9]+}}\\
-    \token{STRING} & = &\mbox{\texttt{"([\^{}\textbackslash"]|"")*"}}\\
-    \token{CHAR}   & = &\mbox{\texttt{'([\^{}']|''|\textbackslash n|\textbackslash t)'}}
-  \end{array}
-  \]
-  \caption{Identifiers and constants}
-  \label{idents_and_consts}
-\end{figure}
-
-
-\subsection{Keywords}
-
-The following identifiers are reserved for keywords:
-
-\begin{lstlisting}
-    after   array   at      before  boxed   case    do      elif    else
-    esac    eta     false   fi      for     fun     if      import  infix
-    infixl  infixr  lazy    length  local   od      of      public  repeat
-    return  sexp    skip    string  string  then    true    unboxed until
-    when    while
-\end{lstlisting}
-
-\subsection{Infix Operators}
-
-Infix operators defined as follows:
-
-\[
-\token{INFIX}=\mbox{\texttt{[+*/\%\$\#@!|\&\^{}~?<>:=\textbackslash-]+}}
-\]
-
-There is a predefined set of built-in infix operators (see Fig.~\ref{builtin_infixes}); additionally
-an end-used can define custom infix operators (see Section~\ref{sec:custom_infix}). Note, sometimes 
-additional whitespaces are required to disambiguate infix operator applications. For example, if a
-custom infix operator "\lstinline|+-|" is defined, then the expression "\lstinline|a +- b|" can no longer be
-recognized as "\lstinline|a +(-b)|". Note also that a custom operator containing "\lstinline|--|" can not be
-defined due to lexical conventions.
-
-\subsection{Delimiters}
-
-The following symbols are treated as delimiters:
-
-\begin{lstlisting}
-    .       ,         (        )        {        }
-    ;       #         ->
-\end{lstlisting}
-
-Despite custom infix operators can coincide with delimiters "\lstinline|#|" and "\lstinline|->|" they can
-never clash as neither of these delimiters can be encountered in expressions in infix operator position.
-
-