CHR Built-In Predicates

There are some built-in predicates to compile chr files, for debugging, built-in labeling and to inspect the constraint store and remove its constraints:

• chr2pl(File)  compiles ``File'' from a chr to pl file.
• chr(File)  compiles ``File'' from a chr to pl file and loads the pl file.
• chr_trace  activates the standard debugger and shows constraint handling.
• chr_notrace  stops either debugger.
• chr_labeling  provides built-in labeling (see corresponding subsection).
• chr_label_with(Constraint)  checks if ``Constraint'' satisfies a label_with declaration (used for built-in labeling).
• chr_resolve(Constraint)  uses the ECLiPSe clauses to solve a constraint (used for built-in labeling).
• chr_get_constraint(Constraint)  gets a constraint unifying with ``Constraint'' from the constraint store and removes it, gets another constraint on backtracking.
• chr_get_constraint(Variable,Constraint)  is the same as chr_get_constraint/1 except that the constraint constrains the variable ``Variable''.