From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 24 Feb 2019 22:15:00 +0000 (-0700)
Subject: make better use of can_be in between library
X-Git-Tag: v0.8.110~225
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=7f8c6eb3f5e862ce3d2a8e5b5a0825dc03ebf0d5;p=scryer-prolog.git

make better use of can_be in between library
---

diff --git a/src/prolog/lib/between.pl b/src/prolog/lib/between.pl
index 78aaf26f..60c2a99a 100644
--- a/src/prolog/lib/between.pl
+++ b/src/prolog/lib/between.pl
@@ -18,11 +18,10 @@ enumerate_nats(I0, N) :-
     enumerate_nats(I1, N).
 
 gen_nat(N) :-
-    integer(N), !, N >= 0.
-gen_nat(N) :-
-    var(N), !, enumerate_nats(0, N).
-gen_nat(N) :-
-    throw(error(type_error(integer, N), gen_nat/1)).
+    can_be(integer, N),
+    (   var(N) -> enumerate_nats(0, N)
+    ;   true
+    ).
 
 enumerate_ints(I, I).
 enumerate_ints(I0, N) :-
@@ -33,11 +32,10 @@ enumerate_ints(I0, N) :-
     enumerate_ints(I1, N).
 
 gen_int(N) :-
-    integer(N), !.
-gen_int(N) :-
-    var(N), !, enumerate_ints(0, N).
-gen_int(N) :-
-    throw(error(type_error(integer, N), gen_int/1)).
+    can_be(integer, N),
+    (   var(N) -> enumerate_ints(0, N)
+    ;   true
+    ).
 
 repeat_integer(N) :-
     N > 0.