From: Markus Triska <triska@metalevel.at>
Date: Sun, 15 Aug 2021 10:28:02 +0000 (+0200)
Subject: ENHANCED: Domain error non_empty_list for empty arguments, addressing #1024.
X-Git-Tag: v0.9.0~47^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=9e13f184638968da2b2762bb647209eac71deb5a;p=scryer-prolog.git

ENHANCED: Domain error non_empty_list for empty arguments, addressing #1024.

Example:

    ?- format("~d", []).
    %@ caught: error(domain_error(non_empty_list,[]),format_//2)
---

diff --git a/src/lib/format.pl b/src/lib/format.pl
index f5bb0b05..e8964304 100644
--- a/src/lib/format.pl
+++ b/src/lib/format.pl
@@ -284,9 +284,11 @@ cells([~|Fs0], Args0, Tab0, Es, VNs) -->
         { Tab is Tab0 + Num },
         cell(Tab0, Tab, Es),
         cells(Fs, Args, Tab, [], VNs).
-cells([~,C|_], _, _, _, _) -->
-        { atom_chars(A, [~,C]),
-          domain_error(format_string, A, format_//2) }.
+cells([~|Cs], Args, _, _, _) -->
+        (   { Args == [] } ->
+            { domain_error(non_empty_list, [], format_//2) }
+        ;   { domain_error(format_string, [~|Cs], format_//2) }
+        ).
 cells(Fs0, Args, Tab, Es, VNs) -->
         { phrase(upto_what(Fs1, ~), Fs0, Fs),
           Fs1 = [_|_] },