[m-dev.] For review: minor additions to list.m and string.m

[Ralph Becket]

Estimated hours taken: 0.25

Small additions to list and string.

library/list.m:
	Added func ++/2 as a synonym for list__append/2.
	Added func '..'/1 to generate ascending/descending integer range
lists.

library/string.m:
	Added func ++/2 as a synonym for string__append/2.

? 2000-09-07.diff
? 2000-09-07.log
Index: list.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/list.m,v
retrieving revision 1.92
diff -u -r1.92 list.m
--- list.m	2000/07/19 03:41:54	1.92
+++ list.m	2000/09/07 15:49:43
@@ -86,7 +86,11 @@
 	% to a rewrite rule.
 :- promise all [L,H,T] ( append([H], T, L) <=> L = [H|T] ).
 
+	% L1 ++ L2 = L :- list__append(L1, L2, L).
+	% 
+:- func list(T) ++ list(T) = list(T).
 
+
 	% list__remove_suffix(List, Suffix, Prefix):
 	%	The same as list__append(Prefix, Suffix, List) except that
 	%	this is semidet whereas list__append(out, in, in) is nondet.
@@ -500,6 +504,13 @@
 :- mode list__merge_and_remove_dups(pred(in, in, out) is det,
 	in, in, out) is det.
 
+%
----------------------------------------------------------------------------
%
+
+	% N `..` M = [N, N + 1, N + 2, ..., M]	if N =< M
+	%          = [N, N - 1, N - 2, ..., M]	if M < N
+	%
+:- func int `..` int = list(int).
+
 
%---------------------------------------------------------------------------
--%
 
%---------------------------------------------------------------------------
--%
 
@@ -1321,3 +1332,23 @@
 	P = ( pred(X::in, Y::in, Z::out) is det :- Z = F(X, Y) ),
 	list__merge_and_remove_dups(P, Xs, Ys, Zs).
 
+%
----------------------------------------------------------------------------
%
+
+L1 ++ L2 = list__append(L1, L2).
+
+%
----------------------------------------------------------------------------
%
+
+N `..` M = int_series(N, M, [], ( if N =< M then plus(-1) else plus(1) )).
+
+%
----------------------------------------------------------------------------
%
+
+	% Construct the series [F^n(M), F^(n-1)(M), ..., F(M), M]
+	% where F^n(M) = N
+	%
+:- func int_series(int, int, list(int), func(int) = int) = list(int).
+
+int_series(N, M, Acc, F) =
+	( if N = M then [N | Acc] else int_series(N, F(M), [M | Acc], F) ).
+
+%
----------------------------------------------------------------------------
%
+%
----------------------------------------------------------------------------
%
Index: string.m
===================================================================
RCS file: /home/mercury1/repository/mercury/library/string.m,v
retrieving revision 1.127
diff -u -r1.127 string.m
--- string.m	2000/08/17 09:58:05	1.127
+++ string.m	2000/09/07 15:49:48
@@ -34,6 +34,11 @@
 %       that it is semidet.  Use string__remove_suffix instead.
 % :- mode string__append(out, in, in) is semidet.
 
+:- func string ++ string = string.
+%	S1 ++ S2 = S :- string__append(S1, S2, S).
+%
+%	Nicer syntax.
+
 :- pred string__remove_suffix(string, string, string).
 :- mode string__remove_suffix(in, in, out) is semidet.
 %	string__remove_suffix(String, Suffix, Prefix):
@@ -1874,6 +1879,10 @@
 	  else
 		preceding_boundary(SepP, String, I - 1)
 	).
+
+%
----------------------------------------------------------------------------
%
+
+S1 ++ S2 = string__append(S1, S2).
 
 %
----------------------------------------------------------------------------
%
 %
----------------------------------------------------------------------------
%

--
Ralph Becket      |      MSR Cambridge      |      rbeck at microsoft.com 
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