bug#21915: write inconsistent about #nil
Taylan Kammer <[email protected]>
| Newsgroups | gmane.lisp.guile.bugs |
|---|---|
| Message-ID | <[email protected]> |
On 14.05.2021 15:34, Taylan Kammer wrote: > > It might also be good, in addition, to make the Scheme writer > write (foo . #nil) as (foo . #nil). The positive is that it > would make bugs in Elisp compatibility easier to see by not > masking the fact that one has #nil instead of () at the end > of a list. The only negative I can think of is that it would > be mildly annoying to see (foo bar . #nil) where you expected > to see (foo bar), but I don't think that's ever really harmful. > FWIW here's a tiny patch that realizes this change. - Taylan
0001-Don-t-write-foo-.-nil-as-foo.patch
(text/plain, 1 KB)
From 264b0f3eaead2e6460d32c6cd7f00868656ad891 Mon Sep 17 00:00:00 2001 From: Taylan Kammer <[email protected]> Date: Fri, 14 May 2021 23:26:16 +0200 Subject: [PATCH] Don't write (foo . #nil) as (foo). Elisp needs its own writer that produced output that will be understood by Elisp's read. Scheme's write shouldn't hide away a #nil terminating a list, as this might make some bugs harder to find. * libguile/print.c (scm_iprlist): Use scm_is_null_and_not_nil in place of SCM_NULL_OR_NIL_P. --- libguile/print.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libguile/print.c b/libguile/print.c index b10f0f8a8..2bdf1760b 100644 --- a/libguile/print.c +++ b/libguile/print.c @@ -1018,7 +1018,7 @@ scm_iprlist (char *hdr, SCM exp, int tlr, SCM port, scm_print_state *pstate) /* CHECK_INTS; */ scm_iprin1 (SCM_CAR (exp), port, pstate); } - if (!SCM_NULL_OR_NIL_P (exp)) + if (!scm_is_null_and_not_nil (exp)) { scm_puts (" . ", port); scm_iprin1 (exp, port, pstate); -- 2.30.2