src/Pure/Syntax/README

added constdefs section

                              Pure/Syntax/

This directory contains the source files for Isabelle's syntax module, which
includes a lexer, parser, pretty printer and macro system. Note that only the
following structures are supposed to be exported:

  Pretty        (generic pretty printing module)
  Scanner       (generic scanner toolbox)

  Syntax        (interface to the syntax module)
  BasicSyntax   (part of Syntax made pervasive)

There is no Makefile to compile these files separately; they are compiled as
part of Pure Isabelle.