KRB Syntax

This section describes the syntax for defining rules in KRB files.

Keywords

as	foreach	taking
assert	in	True
bc_extras	None	use
check	plan_extras	when
extending	python	with
False	step	without
fc_extras

Syntax of the Entire KRB File

file ::= [NL]

         ['extending' IDENTIFIER ['without' {IDENTIFIER,}] NL]

         [{fc_rule}
          ['fc_extras' NL INDENT
             {<python_statement> NL}
           DEINDENT]]

         [{bc_rule}
          ['bc_extras' NL INDENT
             {<python_statement> NL}
           DEINDENT]
          ['plan_extras' NL INDENT
             {<python_statement> NL}
           DEINDENT]]

The KRB file has three optional parts. It must contain at least one rule (either forward-chaining or backward-chaining).

The filename (minus the .krb extension) is the name of the rule base. This must be a legal Python identifier.

Extending clause

The optional extending clause, if used, is the first line of the file. This defines the parent rule base that this rule base inherits from. It may also specify a list of backward-chaining goal names to be excluded from this inheritance.

Forward-Chaining Section

If the krb file contains any forward-chaining rules, a Python source file will be created named <rb_name>_fc.py, where <rb_name> is the rule base name.

The syntax of a forward-chaining rule (fc_rule) is defined here.

The fc_extras may only be used if there are forward-chaining rules. This allows you to add other Python code (for example, import statements) to the generated Python source file.

Backward-Chaining Section

If the krb file contains any backward-chaining rules, a Python source file will be created named <rb_name>_bc.py, where <rb_name> is the rule base name.

The syntax of a backward-chaining rule (bc_rule) is defined here.

The bc_extras can only be used if there are backward-chaining rules. This allows you to add other Python code (for example, import statements) to the generated Python source file.

In addition, if any of the backward-chaining rules have plan code (a with clause or any subgoals in the when clause with a plan_spec), a Python source file will be created named <rb_name>_plans.py, where <rb_name> is the rule base name.