From: Mark Thom <markjordanthom@gmail.com>
Date: Wed, 19 Feb 2020 22:55:56 +0000 (-0700)
Subject: update between/3 to allow inf as upper bound
X-Git-Tag: v0.8.118~4
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=617f803355d1cf1c0b38712b76a3ac647267b3f4;p=scryer-prolog.git

update between/3 to allow inf as upper bound
---

diff --git a/src/prolog/lib/between.pl b/src/prolog/lib/between.pl
index 16c73145..a8e06882 100644
--- a/src/prolog/lib/between.pl
+++ b/src/prolog/lib/between.pl
@@ -6,10 +6,15 @@
 :- use_module(library(error)).
 
 between(Lower, Upper, X) :-
-    must_be(integer, Lower),
-    must_be(integer, Upper),
-    can_be(integer, X),
-    between_(Lower, Upper, X).
+    (  Upper == inf ->
+       must_be(integer, Lower),
+       can_be(integer, X),
+       enumerate_nats(Lower, X)
+    ;  must_be(integer, Lower),
+       must_be(integer, Upper),
+       can_be(integer, X),
+       between_(Lower, Upper, X)
+    ).
 
 between_(Lower, Upper, Lower) :-
     Lower =< Upper.