From: Mark Thom <markjordanthom@gmail.com>
Date: Mon, 4 Mar 2019 00:36:20 +0000 (-0700)
Subject: condense reverse even further
X-Git-Tag: v0.8.110~215
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=f35008cbd64590b281a240f9f5cec63fddc58bee;p=scryer-prolog.git

condense reverse even further
---

diff --git a/src/prolog/lib/dif.pl b/src/prolog/lib/dif.pl
index e830a206..72101b82 100644
--- a/src/prolog/lib/dif.pl
+++ b/src/prolog/lib/dif.pl
@@ -37,7 +37,8 @@ verify_attributes(Var, Value, Goals) :-
 % suggestions for improvement.
 
 dif(X, Y) :- X \== Y,
-             (   term_variables(X, XVars), term_variables(Y, YVars),
+             (   X \= Y -> true
+	     ;   term_variables(X, XVars), term_variables(Y, YVars),
 	         dif_set_variables(XVars, X, Y),
 		 dif_set_variables(YVars, X, Y)
 	     ).
diff --git a/src/prolog/lib/lists.pl b/src/prolog/lib/lists.pl
index 7382a144..b058b2c5 100644
--- a/src/prolog/lib/lists.pl
+++ b/src/prolog/lib/lists.pl
@@ -42,13 +42,13 @@ append([X|L], R, [X|S]) :- append(L, R, S).
 memberchk(X, Xs) :- member(X, Xs), !.
 
 reverse(Xs, Ys) :-
-    (  var(Ys) -> reverse(Xs, Ys, [], [], Xs)
-    ;  reverse(Ys, Xs, [], [], Ys)
+    (  var(Ys) -> reverse(Xs, Ys, [], Xs)
+    ;  reverse(Ys, Xs, [], Ys)
     ).
 
-reverse([], [], XsRev, YsRev, YsRev).
-reverse([X1|Xs], [Y1|Ys], XsPreludeRev, YsPreludeRev, Xss) :-
-    reverse(Xs, Ys, [X1|XsPreludeRev], [Y1|YsPreludeRev], Xss).
+reverse([], [], YsRev, YsRev).
+reverse([X1|Xs], [Y1|Ys], YsPreludeRev, Xss) :-
+    reverse(Xs, Ys, [Y1|YsPreludeRev], Xss).
 
 maplist(_, []).
 maplist(Cont1, [E1|E1s]) :-