lib(ech)

   This library allows the user to write constraint handling rules (CHR) in 
   their ECLiPSe programs. CHR is a high-level language extension for writing
   user-defined constraints, allowing for rapid prototyping of constraints.

   This library provides some extensions over the older chr library: 

     support for multi (>2) headed simplification and simpagation rules

     cleanup of semantics and syntax of CHRs

     faster execution

     more convenient compilation and mixing with ECLiPSe code

   CHRs are compiled by source-to-source transformation into ECLiPSe code that
   make calls to many ech library predicates that implements the CHR 
   functionality. Thus, most exported predicates predicates  are not intended
   to be used by the user directly, and are not documented.


