apply_macros.pl -- Goal expansion rules to avoid meta-calling

This module defines goal_expansion/2 rules to deal with commonly used, but fundamentally slow meta-predicates. Notable maplist/2... defines a useful set of predicates, but its execution is considerable slower than a traditional Prolog loop. Using this library calls to maplist/2... are translated into an call to a generated auxiliary predicate that is compiled using compile_aux_clauses/1. Currently this module supports:

• maplist/2..
• forall/2
• once/1
• ignore/1
• phrase/2
• phrase/3
• call_dcg/2
• call_dcg/3

The idea for this library originates from ECLiPSe and came to SWI-Prolog through YAP.

author

- Jan Wielemaker

To be done

- Support more predicates

 expand_phrase(+PhraseGoal, -Goal) is semidet

 expand_phrase(+PhraseGoal, +Pos0, -Goal, -Pos) is semidet

Provide goal-expansion for PhraseGoal. PhraseGoal is either phrase/2,3 or call_dcg/2,3. The current version does not translate control structures, but only simple terminals and non-terminals.

For example:

?- expand_phrase(phrase(("ab", rule)), List), Goal).
Goal = (List=[97, 98|_G121], rule(_G121, [])).

throws

- Re-throws errors from dcg_translate_rule/2

 apply_macros_sentinel

Used to detect that library(apply_macros) is loaded into the current context explicitly. This test is used if the Prolog flag apply_macros is set to imported.

Re-exported predicates

The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.

 expand_phrase(+PhraseGoal, -Goal) is semidet

 expand_phrase(+PhraseGoal, +Pos0, -Goal, -Pos) is semidet

Provide goal-expansion for PhraseGoal. PhraseGoal is either phrase/2,3 or call_dcg/2,3. The current version does not translate control structures, but only simple terminals and non-terminals.

For example:

?- expand_phrase(phrase(("ab", rule)), List), Goal).
Goal = (List=[97, 98|_G121], rule(_G121, [])).

throws

- Re-throws errors from dcg_translate_rule/2