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authorAndy Wingo <wingo@pobox.com>2010-03-23 20:23:19 +0100
committerAndy Wingo <wingo@pobox.com>2010-03-30 10:31:27 +0200
commitd38b431ace4b01e5da9cb09bb6341277f2974160 (patch)
tree745db83549f083455e0ac4e96058da3e67acbba7
parent655aadf4b09c40f4c7854e4325e8809fcb7cb36b (diff)
downloadguile-d38b431ace4b01e5da9cb09bb6341277f2974160.tar.gz
nil is false, whee
* libguile/boolean.h (scm_is_false): Recognize nil as false, by default. (scm_is_bool): Recognize nil as a boolean. * libguile/boolean.c (scm_not, scm_boolean, scm_to_bool, scm_is_bool): Adapt to treat nil as false. * libguile/vm-i-system.c (br-if, br-if-not): Just use scm_is_false instead of specifically mentioning nil.
-rw-r--r--libguile/boolean.c13
-rw-r--r--libguile/boolean.h11
-rw-r--r--libguile/vm-i-system.c4
3 files changed, 14 insertions, 14 deletions
diff --git a/libguile/boolean.c b/libguile/boolean.c
index 3391d6ce5..7d58582a2 100644
--- a/libguile/boolean.c
+++ b/libguile/boolean.c
@@ -56,28 +56,27 @@ verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
SCM_DEFINE (scm_not, "not", 1, 0, 0,
(SCM x),
- "Return @code{#t} iff @var{x} is @code{#f}, else return @code{#f}.")
+ "Return @code{#t} iff @var{x} is false, else return @code{#f}.")
#define FUNC_NAME s_scm_not
{
- return scm_from_bool (scm_is_false_or_nil (x));
+ return scm_from_bool (scm_is_false (x));
}
#undef FUNC_NAME
SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0,
(SCM obj),
- "Return @code{#t} iff @var{obj} is either @code{#t} or @code{#f}.")
+ "Return @code{#t} iff @var{obj} is @code{#t} or false.")
#define FUNC_NAME s_scm_boolean_p
{
- return scm_from_bool (scm_is_bool_or_nil (obj));
+ return scm_from_bool (scm_is_bool (obj));
}
#undef FUNC_NAME
int
scm_to_bool (SCM x)
{
- /* XXX Should this first test use scm_is_false_or_nil instead? */
- if (scm_is_eq (x, SCM_BOOL_F))
+ if (scm_is_false (x))
return 0;
else if (scm_is_eq (x, SCM_BOOL_T))
return 1;
@@ -93,7 +92,7 @@ int
scm_is_bool (SCM obj)
{
/* This must match the macro definition of `scm_is_bool ()'. */
- return scm_is_bool_and_not_nil (obj);
+ return scm_is_bool_or_nil (obj);
}
diff --git a/libguile/boolean.h b/libguile/boolean.h
index bc108f5c3..007500e10 100644
--- a/libguile/boolean.h
+++ b/libguile/boolean.h
@@ -27,7 +27,9 @@
-/* Boolean Values
+/* Boolean Values. Obviously there are #t and #f, but there is also nil to deal
+ * with. We choose to treat nil as a false boolean. All options might silently
+ * break existing code, but this one seems most responsible.
*
*/
@@ -58,8 +60,8 @@
#endif
#define scm_is_true_and_not_nil(x) (!scm_is_false_or_nil (x))
-/* XXX Should these macros treat %nil as false by default? */
-#define scm_is_false(x) (scm_is_false_and_not_nil (x))
+/* %nil is false. */
+#define scm_is_false(x) (scm_is_false_or_nil (x))
#define scm_is_true(x) (!scm_is_false (x))
/*
@@ -90,8 +92,7 @@
SCM_API int scm_is_bool (SCM);
-/* XXX Should scm_is_bool treat %nil as a boolean? */
-#define scm_is_bool(x) (scm_is_bool_and_not_nil (x))
+#define scm_is_bool(x) (scm_is_bool_or_nil (x))
#define scm_from_bool(x) ((x) ? SCM_BOOL_T : SCM_BOOL_F)
SCM_API int scm_to_bool (SCM x);
diff --git a/libguile/vm-i-system.c b/libguile/vm-i-system.c
index 27c6c3374..76ae0691d 100644
--- a/libguile/vm-i-system.c
+++ b/libguile/vm-i-system.c
@@ -484,12 +484,12 @@ VM_DEFINE_INSTRUCTION (35, br, "br", 3, 0, 0)
VM_DEFINE_INSTRUCTION (36, br_if, "br-if", 3, 0, 0)
{
- BR (scm_is_true_and_not_nil (*sp));
+ BR (scm_is_true (*sp));
}
VM_DEFINE_INSTRUCTION (37, br_if_not, "br-if-not", 3, 0, 0)
{
- BR (scm_is_false_or_nil (*sp));
+ BR (scm_is_false (*sp));
}
VM_DEFINE_INSTRUCTION (38, br_if_eq, "br-if-eq", 3, 0, 0)