[m-rev.] diff: add list.foldl_corresponding3/6 etc

[Julien Fischer]

I've found a need for the following while converting more of the HLDS
to use proc_arg_vectors instead of lists.

Estimated hours taken: 0.5
Branches: main

library/list.m:
 	Add several new higher-order predicates for performing folds
 	over three corresponding lists: list.foldl_corresponding3/6,
 	list.foldl2_corresponding3/8 and list.foldl3_corresponding3/10.

 	Fix a comment.

NEWS:
 	Merge the existing entries for the list module into a single entry.

 	Mention the new predicates.

Julien.

Index: NEWS
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/NEWS,v
retrieving revision 1.434
diff -u -r1.434 NEWS
--- NEWS	2 Jan 2007 07:37:54 -0000	1.434
+++ NEWS	4 Jan 2007 04:01:07 -0000
@@ -15,18 +15,21 @@

  Changes to the Mercury standard library:

-* We have added list.map_corresponding/4, a predicate version of 
-  list.map_corresponding/3.
+* The following predicates have been added to the list module:
+	list.map_corresponding/4
+	list.map2_foldl3/10
+	list.map_corresponding_foldl/6
+	list.map_corresponding3_foldl/7
+	list.foldl_corresponding3/6
+	list.foldl2_corresponding3/8
+	list.foldl3_corresponding3/10

-* We have added versions of list.foldl/4 and list.foldr/4 that have 
-  determinism multi.
+   We have also added versions of list.foldl/4 and list.foldr/4 that have
+   determinism multi.

  * We have changed the interface of the ops module to make lookups of operators
    more efficient.

-* We have added list.map2_foldl3/10, list.map_corresponding_foldl/6 and
-  list.map_corresponding3_foldl/7 
-
  * We have added io.update_globals/3 which allows for atomic updates to
    the globals field in the I/O state in the presence of multiple threads.

Index: library/list.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/library/list.m,v
retrieving revision 1.158
diff -u -r1.158 list.m
--- library/list.m	2 Jan 2007 07:37:54 -0000	1.158
+++ library/list.m	4 Jan 2007 03:55:58 -0000
@@ -634,7 +634,7 @@
  :- mode list.map_corresponding_foldl(pred(in, in, out, di, uo) is det,
      in, in, out, di, uo) is det.

-    % list.map_corresponding3_foldl7 is like list.map_corresponding3 except
+    % list.map_corresponding3_foldl/7 is like list.map_corresponding3 except
      % that it has an accumulator threaded through it.
      %
  :- pred list.map_corresponding3_foldl(pred(A, B, C, D, E, E),
@@ -833,6 +833,47 @@
  :- mode list.foldl2_corresponding(pred(in, in, in, out, di, uo) is cc_multi,
      in, in, in, out, di, uo) is cc_multi.

+    % list.foldl_corresponding3(P, As, Bs, Cs, !Acc):
+    % Like list.foldl_corresponding but folds over three corresponding
+    % lists.
+    %
+:- pred list.foldl_corresponding3(pred(A, B, C, D, D),
+    list(A), list(B), list(C), D, D).
+:- mode list.foldl_corresponding3(pred(in, in, in, in, out) is det,
+    in, in, in, in, out) is det.
+:- mode list.foldl_corresponding3(pred(in, in, in, di, uo) is det,
+    in, in, in, di, uo) is det.
+:- mode list.foldl_corresponding3(pred(in, in, in, in, out) is semidet,
+    in, in, in, in, out) is semidet.
+
+    % list.foldl2_corresponding3(P, As, Bs, Cs, !Acc1, !Acc2):
+    % like list.foldl_corresponding3 but with two accumulators.
+    %
+:- pred list.foldl2_corresponding3(pred(A, B, C, D, D, E, E),
+    list(A), list(B), list(C), D, D, E, E).
+:- mode list.foldl2_corresponding3(pred(in, in, in, in, out, in, out) is det,
+    in, in, in, in, out, in, out) is det.
+:- mode list.foldl2_corresponding3(pred(in, in, in, in, out, di, uo) is det,
+    in, in, in, in, out, di, uo) is det.
+:- mode list.foldl2_corresponding3(
+    pred(in, in, in, in, out, in, out) is semidet,
+    in, in, in, in, out, in, out) is semidet.
+
+    % list.foldl3_corresponding3(P, As, Bs, Cs, !Acc1, !Acc2, !Acc3):
+    % like list.foldl_corresponding3 but with three accumulators.
+    %
+:- pred list.foldl3_corresponding3(pred(A, B, C, D, D, E, E, F, F),
+    list(A), list(B), list(C), D, D, E, E, F, F).
+:- mode list.foldl3_corresponding3(
+    pred(in, in, in, in, out, in, out, in, out) is det,
+    in, in, in, in, out, in, out, in, out) is det.
+:- mode list.foldl3_corresponding3(
+    pred(in, in, in, in, out, in, out, di, uo) is det,
+    in, in, in, in, out, in, out, di, uo) is det.
+:- mode list.foldl3_corresponding3(
+    pred(in, in, in, in, out, in, out, in, out) is semidet,
+    in, in, in, in, out, in, out, in, out) is semidet.
+
      % list.map_foldl(Pred, InList, OutList, Start, End) calls Pred
      % with an accumulator (with the initial value of Start) on
      % each element of InList (working left-to-right) to transform
@@ -1947,6 +1988,59 @@
      P(A, B, !Acc1, !Acc2),
      list.foldl2_corresponding(P, As, Bs, !Acc1, !Acc2).

+list.foldl_corresponding3(_, [], [], [], !Acc).
+list.foldl_corresponding3(_, [_ | _], [], [], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(_, [], [_ | _], [], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(_, [], [], [_ | _], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(_, [], [_ | _], [_ | _], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(_, [_ | _], [], [_ | _], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(_, [_ | _], [_ | _], [], _, _) :-
+    error("list.foldl_corresponding3/6: mismatched list arguments").
+list.foldl_corresponding3(P, [ A | As ], [ B | Bs ], [ C | Cs], !Acc) :-
+    P(A, B, C, !Acc),
+    list.foldl_corresponding3(P, As, Bs, Cs, !Acc).
+
+list.foldl2_corresponding3(_, [], [], [], !Acc1, !Acc2).
+list.foldl2_corresponding3(_, [_ | _], [], [], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(_, [], [_ | _], [], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(_, [], [], [_ | _], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(_, [], [_ | _], [_ | _], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(_, [_ | _], [], [_ | _], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(_, [_ | _], [_ | _], [], _, _, _, _) :-
+    error("list.foldl2_corresponding3/8: mismatched list arguments").
+list.foldl2_corresponding3(P, [ A | As ], [ B | Bs ], [ C | Cs],
+        !Acc1, !Acc2) :-
+    P(A, B, C, !Acc1, !Acc2),
+    list.foldl2_corresponding3(P, As, Bs, Cs, !Acc1, !Acc2).
+
+list.foldl3_corresponding3(_, [], [], [], !Acc1, !Acc2, !Acc3).
+list.foldl3_corresponding3(_, [_ | _], [], [], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(_, [], [_ | _], [], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(_, [], [], [_ | _], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(_, [], [_ | _], [_ | _], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(_, [_ | _], [], [_ | _], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(_, [_ | _], [_ | _], [], _, _, _, _, _, _) :-
+    error("list.foldl3_corresponding3/10: mismatched list arguments").
+list.foldl3_corresponding3(P, [ A | As ], [ B | Bs ], [ C | Cs],
+        !Acc1, !Acc2, !Acc3) :-
+    P(A, B, C, !Acc1, !Acc2, !Acc3),
+    list.foldl3_corresponding3(P, As, Bs, Cs, !Acc1, !Acc2, !Acc3).
+
  list.map_foldl(_, [], [], !A).
  list.map_foldl(P, [H0 | T0], [H | T], !A) :-
      P(H0, H, !A),

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