Changeset 4593 for trunk/library

Timestamp:

11/18/08 03:37:21 (7 weeks ago)

Author:

pmoura

Message:

Added predicates included/3, excluded/3, fold_left/4, and fold_right/4 to the library entities "metap" and "meta" (requested by Paul Crocker). Renamed the predicates filter/3 and succeeds/2 to included/3 and map/2, respectively (older names are still available using aliases in "meta").

Location:

trunk/library

Files:

• meta.lgt (modified) (4 diffs)
• metap.lgt (modified) (5 diffs)

trunk/library/meta.lgt

@@ -4 +4 @@
 
     :- info([
-        version is 2.2,
-        date is 2008/10/5,
+        version is 2.3,
+        date is 2008/11/18,
         author is 'Paulo Moura',
         comment is 'Some useful meta-predicates.']).
+
+    :- alias(metap, map/2, succeeds/2).
+    :- alias(metap, include/3, filter/3).
 
     callable(Term) :-
@@ -14 +17 @@
         atom(Functor).
 
-    :- meta_predicate(filter(1, *, *)).
-    filter(_, [], []) :- !.
-    filter(Closure, [Arg| Args], In) :-
+    :- meta_predicate(include(1, *, *)).
+    include(_, [], []) :- !.
+    include(Closure, [Arg| Args], Included) :-
         (   call(Closure, Arg) ->
-            In = [Arg| RIn]
-        ;   In = RIn
+            Included = [Arg| Rest]
+        ;   Included = Rest
         ),
-        filter(Closure, Args, RIn).
+        include(Closure, Args, Rest).
+
+    :- meta_predicate(exclude(1, *, *)).
+    exclude(_, [], []) :- !.
+    exclude(Closure, [Arg| Args], Excluded) :-
+        (   call(Closure, Arg) ->
+            Excluded = Rest
+        ;   Excluded = [Arg| Rest]
+        ),
+        exclude(Closure, Args, Rest).
 
     :- meta_predicate(partition(1, *, *, *)).
     partition(_, [], [], []) :- !.
-    partition(Closure, [Arg| Args], In, Out) :-
+    partition(Closure, [Arg| Args], Included, Excluded) :-
         (   call(Closure, Arg) ->
-            In = [Arg| RIn],
-            Out = ROut
-        ;   In = RIn,
-            Out = [Arg| ROut]
+            Included = [Arg| RestIncluded],
+            Excluded = RestExcluded
+        ;   Included = RestIncluded,
+            Excluded = [Arg| RestExcluded]
         ),
-        partition(Closure, Args, RIn, ROut).
+        partition(Closure, Args, RestIncluded, RestExcluded).
 
     :- meta_predicate(ignore(::)).
@@ -40 +52 @@
         ;   true
         ).
+
+    :- meta_predicate(fold_left(3, *, *, *)).
+    fold_left(_, Result, [], Result).
+    fold_left(Closure, Acc, [Arg| Args], Result) :-
+        call(Closure, Acc, Arg, Acc2),
+        fold_left(Closure, Acc2, Args, Result).
+
+    :- meta_predicate(fold_right(3, *, *, *)).
+    fold_right(_, Result, [], Result).
+    fold_right(Closure, Acc, [Arg| Args], Result) :-
+        fold_right(Closure, Acc, Args, Acc2),
+        call(Closure, Arg, Acc2, Result).
+
+    :- meta_predicate(map(1, *)).
+    map(_, []).
+    map(Closure, [Head| Tail]) :-
+        call(Closure, Head),
+        map(Closure, Tail).
 
     :- meta_predicate(map(2, *, *)).
@@ -59 +89 @@
         map(Closure, As, Bs, Cs, Ds).
 
-    :- meta_predicate(succeeds(1, *)).
-    succeeds(_, []).
-    succeeds(Closure, [Head| Tail]) :-
-        call(Closure, Head),
-        succeeds(Closure, Tail).
-
 :- end_object.

trunk/library/metap.lgt

@@ -3 +3 @@
 
     :- info([
-        version is 3.1,
-        date is 2008/10/5,
+        version is 3.2,
+        date is 2008/11/18,
         author is 'Paulo Moura',
         comment is 'Useful meta-predicates protocol.']).
@@ -14 +14 @@
         argnames is ['Term']]).
 
-    :- public(filter/3).
-    :- meta_predicate(filter(1, *, *)).
-    :- mode(filter(+callable, +list, -list), one).
-    :- info(filter/3, [
+    :- public(include/3).
+    :- meta_predicate(include(1, *, *)).
+    :- mode(include(+callable, +list, -list), one).
+    :- info(include/3, [
         comment is 'Returns a list of all list elements that satisfy a predicate.',
-        argnames is ['Closure', 'List', 'In']]).
+        argnames is ['Closure', 'List', 'Included']]).
+
+    :- public(exclude/3).
+    :- meta_predicate(exclude(1, *, *)).
+    :- mode(exclude(+callable, +list, -list), one).
+    :- info(exclude/3, [
+        comment is 'Returns a list of all list elements that fail to satisfy a predicate.',
+        argnames is ['Closure', 'List', 'Excluded']]).
 
     :- public(partition/4).
@@ -26 +33 @@
     :- info(partition/4, [
         comment is 'Partition a list of elements in two lists using a predicate.',
-        argnames is ['Closure', 'List', 'In', 'Out']]).
+        argnames is ['Closure', 'List', 'Included', 'Excluded']]).
 
     :- public(ignore/1).
@@ -34 +41 @@
         comment is 'Calls Goal once but always succeeds, even if Goal fails.',
         argnames is ['Goal']]).
+
+    :- public(fold_left/4).
+    :- meta_predicate(fold_left(3, *, *, *)).
+    :- mode(fold_left(+callable, ?term, +list, ?term), zero_or_more).
+    :- info(fold_left/4, [
+        comment is 'List folding (left associative).',
+        argnames is ['Closure', 'Accumulator', 'List', 'Result']]).
+
+    :- public(fold_right/4).
+    :- meta_predicate(fold_right(3, *, *, *)).
+    :- mode(fold_right(+callable, ?term, +list, ?term), zero_or_more).
+    :- info(fold_right/4, [
+        comment is 'List folding (right associative).',
+        argnames is ['Closure', 'Accumulator', 'List', 'Result']]).
+
+    :- public(map/2).
+    :- meta_predicate(map(1, *)).
+    :- mode(map(+callable, ?list), zero_or_more).
+    :- info(map/2, [
+        comment is 'True if the predicate succeeds for each list element.',
+        argnames is ['Closure', 'List']]).
 
     :- public(map/3).
@@ -56 +84 @@
         argnames is ['Closure', 'List1', 'List2', 'List3', 'List4']]).
 
-    :- public(succeeds/2).
-    :- meta_predicate(succeeds(1, *)).
-    :- mode(succeeds(+callable, +list), zero_or_more).
-    :- info(succeeds/2, [
-        comment is 'True if the predicate succeeds for each list element.',
-        argnames is ['Closure', 'List']]).
-
 :- end_protocol.