\begin{center}
\begin{tabular}{l l l}
  Syntax Class  & Purpose \\\hline
  \mod{fun/domain}     & Infer function domain types \\
  \mod{num/value}      & Evaluate a numeric expression \\
  \mod{pattern/groups} & Count regexp groups \\
  \mod{query/constr}   & Parse {\tt sql} queries \\
  \mod{schema/spec}    & Lift a schema value from syntax \\
  \mod{string/format}  & Parse format directives \\
  \mod{vector/length}  & Infer length from a vector spec. \\
\end{tabular}
\end{center}
