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doc/spec/03.concrete_syntax.tex
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\chapter{Concrete Syntax}
\begin{figure}[t]
\[
\begin{array}{rcl}
\defterm{compilationUnit} & : & \nonterm{import}^\star\s\nonterm{scopeExpression}\\
\defterm{import} & : & \term{import}\s\token{UIDENT}\s\term{;}
\end{array}
\]
\caption{Compilation unit concrete syntax}
\end{figure}
In this chapter we describe the concrete syntax of the language as it is recognized by the parser. In the
syntactic description we will use extended Backus-Naur form with the following conventions:
\begin{figure}[t]
\[
\begin{array}{rcll}
\defterm{expression} & : & \nonterm{basicExpression}\s(\s\term{;}\s\nonterm{expression}\s)&\\
\defterm{basicExpression} & : & \nonterm{binaryExpression}&\\
\defterm{binaryExpression} & : & \nonterm{binaryOperand}\s\token{INFIX}\s\nonterm{binaryOperand}&\alt\\
& & \nonterm{binaryOperand}&\\
\defterm{binaryOperand} & : & \nonterm{binaryExpression}&\alt\\
& & [\s\term{-}\s]\s\nonterm{postfixExpression}&\\
\defterm{postfixExpression} & : & \nonterm{primary}&\alt\\
& & \nonterm{postfixExpression}\s\term{(}\s[\s\nonterm{expression}\s(\s\term{,}\s\nonterm{expression}\s)^\star\s]\s\term{)}&\alt\\
& & \nonterm{postfixExpression}\s\term{[}\s\nonterm{expression}\s\term{]}&\alt\\
& & \nonterm{postfixExpression}\s\term{.}\s\term{length}&\alt\\
& & \nonterm{postfixExpression}\s\term{.}\s\term{string}&\\
\begin{itemize}
\item nonterminals are presented in \nonterm{italics};
\item concrete terminals are \term{grayed out};
\item classes of terminals are \token{CAPITALIZED};
\item a postfix ``$^\star$'' designates zero-or-more repetitions;
\item square brackets ``$[\dots]$'' designate zero-or-one repetition;
\item round brackets ``$(\dots)$'' are used for grouping;
\item alteration is denoted by ``$\alt$'', sequencing by juxaposition;
\item a colon ``$:$'' separates a nonterminal being defined from its definition.
\end{itemize}
\defterm{primary} & : & \token{DECIMAL}&\alt\\
& & \token{STRING}&\alt\\
& & \token{CHAR}&\alt\\
& & \token{LIDENT}&\alt\\
& & \term{true}&\alt\\
& & \term{false}&\alt\\
& & \term{infix}\s\token{INFIX}&\alt\\
& & \term{skip}&\alt\\
& & \term{fun}\s\term{(}\s\nonterm{functionArguments}\s\term{)}\s\nonterm{functionBody}&\alt\\
& & \term{\{}\s\nonterm{scopeExpression}\s\term{\}}&\alt\\
& & \nonterm{listExpression}&\alt\\
& & \nonterm{arrayExpression}&\alt\\
& & \nonterm{S-expression}&\alt\\
& & \nonterm{ifExpression}&\alt\\
& & \nonterm{whileExpression}&\alt\\
& & \nonterm{repeatExpression}&\alt\\
& & \nonterm{forExpression}&\alt\\
& & \nonterm{caseExpression}&\alt\\
& & \term{(}\s\nonterm{expression}\s\term{)}&
\end{array}
\]
\caption{Expression concrete syntax}
\end{figure}
\begin{figure}[t]
\[
\begin{array}{rcl}
\defterm{scopeExpression} & : & \nonterm{definition}^\star\s\nonterm{expression}\\
\defterm{definition} & : & \nonterm{variableDefinition}\alt\nonterm{functionDefinition}\alt\nonterm{infixDefinition}\\
\defterm{variableDefinition} & : & (\s\term{local}\alt\term{public}\s)\s\nonterm{variableDefinitionSequence}\s\term{;}\\
\defterm{variableDefinitionSequence} & : & \nonterm{variableDefinitionSequenceItem}\s(\s\term{,}\s\nonterm{variableDefinitionSequenceItem}\s)^\star\\
\defterm{variableDefinitionSequenceItem} & : & \token{LIDENT}\s[\s\term{=}\s\nonterm{basicExpression}\s]\\
\defterm{functionDefinition} & : & [\s\term{public}\s]\s\term{fun}\s\token{LIDENT}\s\term{(}\s\nonterm{functionArguments}\s\term{)}\s\nonterm{functionBody}\\
\defterm{functionArguments} & : & [\s\token{LIDENT}\s(\s\term{,}\s\token{LIDENT}\s)^\star\s]\\
\defterm{functionBody} & : & \term{\{}\s\nonterm{scopeExpression}\s\term{\}}
\end{array}
\]
\caption{Scope expression concrete syntax}
\end{figure}
In the description below we will take an in-line code samples in blockquotes "..." which are not considered as a
part of concrete syntax.
\input{03.01.lexical_structure}
\input{03.02.compilation_units}
\input{03.03.scope_expressions}
\input{03.04.expressions}
\begin{figure}[t]
\[