quote single dots only

src/prolog/heap_print.rs

@@ -442,7 +442,9 @@ fn non_quoted_token<Iter: Iterator<Item = char>>(mut iter: Iter) -> bool {
     if let Some(c) = iter.next() {
         if small_letter_char!(c) {
             iter.all(|c| alpha_numeric_char!(c))
-        } else if c != '.' && graphic_token_char!(c) {
+        } else if c == '.' {
+            iter.next().is_some()
+        } else if graphic_token_char!(c) {
             non_quoted_graphic_token(iter, c)
         } else if semicolon_char!(c) {
             iter.next().is_none()

src/prolog/toplevel.pl

@@ -123,7 +123,7 @@
     atom(Value),
     atom_chars(Value, ValueChars),
     '$list_last_item'(ValueChars, Char),
-    Char \== '.',
+    ValueChars \== ['.'],
     '$graphic_token_char'(Char).
 
 '$write_eqs_and_read_input'(B, VarList) :-