SWIProlog can't not emit '.'.

I would like the GNU Prolog and SWI Prolog versions to be compatible, if
possible.

SWI has bigints, GNU doesn't, so that's a wrinkle...

implementations/GNUProlog/parser.prolog

@@ -87,5 +87,5 @@ stdin_to_codes(Code, [Code|Codes]) :-
 :- initialization((
     stdin_to_codes(Codes),
     text_to_expression(Codes, Expr),
-    write_term(Expr, [quoted(true)]), print('\n')
+    write_term(Expr, [quoted(true)]), print('.\n')
     )).

implementations/GNUProlog/printer.prolog

@@ -17,7 +17,7 @@ codes_to_stream([Code|Codes], Stream) :-
 codes_to_stream([], _).
 
 :- initialization((
-    read_term(AST, [end_of_term(eof)]),
+    read_term(AST, []),
     format_joy_terms(AST, Codes, []),
     codes_to_stream(Codes, user_output), print('\n')
     )).

implementations/GNUProlog/thun.prolog

@@ -66,8 +66,8 @@ combo(loop, [list(B),  bool(true)|S], S, Ei, Eo) :- append(B, [list(B), symbol(l
 
 
 :- initialization((
-    read_term(AST, [end_of_term(eof)]),
+    read_term(AST, []),
     thun(AST, [], Stack),
-    write_term(Stack, [quoted(true)]), print('\n')
+    write_term(Stack, [quoted(true)]), print('.\n')
     )).