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:
The idea for this library originates from ECLiPSe and came to SWI-Prolog through YAP.
- expand_maplist(+Callable, +Lists, -Goal) is det[private]
- Macro expansion for maplist/2 and higher arity.
- expand_apply(+GoalIn:callable, -GoalOut) is semidet[private]
- Macro expansion for `apply' predicates.
- expand_apply(+GoalIn:callable, -GoalOut, +PosIn, -PosOut) is semidet[private]
- Translation of simple meta calls to inline code while
maintaining position information. Note that
once(Goal)cannot be translated to(Goal->true)because this will break the compilation of(once(X) ; Y). A correct translation is to(Goal->true;fail). Abramo Bagnara suggested((Goal->true),true), which is both faster and avoids warning ifstyle_check(+var_branches)is used. - 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, [])). - dcg_extend(+Callable, +Pos0, -Goal, -Pos, +Xs0, ?Xs) is semidet[private]
- qcall_instantiated(@Term) is semidet[private]
- True if Term is instantiated sufficiently to call it.
Undocumented predicates
The following predicates are exported, but not or incorrectly documented.