\doc{Signatures}
\ref{signatures}
\ref{domain}
\ref{range}

The \def{signature} of an operator specifies its domain and range sorts.

\head{2}{Syntax}
\begin{verbatim}
\sd{signature} ::= \s{domain} \f{->} \s{range}
\sd{domain}    ::= \slink{sort}{sort}*,
\sd{range}     ::= \slink{sort}{sort}
\end{verbatim}


\head{2}{Examples}
\begin{quote}
\begin{description}
\dt \f{->Nat}                      
\dd
Signature for a nullary operator (constant) of sort \f{Nat}
\p
\dt \f{Bool->Bool}              
\dd
Signature for a unary operator from sort \f{Bool} to sort \f{Bool}
\p
\dt \f{Nat,Nat->Nat}  
\dd        
Signature for a binary operator from sort \f{Nat} to sort \f{Nat}
\p
\dt \f{Element,Set->Set}    
\dd 
Signature for a binary operator from sorts \f{Element} and \f{Set} to sort
\f{Set}
\end{description}
\end{quote}
 
\head{2}{Usage}

Signatures appear in \dlink{../commands/declare}{declarations} and
qualifications for \dlink{operator}{operators}.