From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 24 Feb 2019 10:45:41 +0000 (-0700)
Subject: begin work on between library
X-Git-Tag: v0.8.110~229
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=767f98eaa369874991d54efc9408c34c41f978b7;p=scryer-prolog.git

begin work on between library
---

diff --git a/src/prolog/lib/between.pl b/src/prolog/lib/between.pl
index c6e203f0..e7167ca7 100644
--- a/src/prolog/lib/between.pl
+++ b/src/prolog/lib/between.pl
@@ -82,11 +82,12 @@ diag_ints(M, N) :-
     diag_ints(M0, N0, M, N).
 
 gen_ints(L, U) :-
-    integer(L), !, gen_int(U), L =< U.
-gen_ints(L, U) :-
-    integer(U), !, gen_int(L), L =< U.
-gen_ints(L, U) :-
-    diag_ints(L, U), L =< U.
+    (  integer(L), integer(U), !
+    ;  integer(L) -> gen_int(U)
+    ;  integer(U) -> gen_int(L)
+    ;  diag_ints(L, U)
+    ),
+    L =< U.
 
 numlist(Lower, Upper, List) :-
     gen_ints(Lower, Upper), findall(X, between(Lower, Upper, X), List).