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nil is false, whee

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* 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.
This commit is contained in:
Andy Wingo 2010-03-23 20:23:19 +01:00
parent 655aadf4b0
commit d38b431ace
3 changed files with 14 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

13
libguile/boolean.c
View file

@ -56,28 +56,27 @@ verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
SCM_DEFINE (scm_not, "not", 1, 0, 0, SCM_DEFINE (scm_not, "not", 1, 0, 0,
(SCM x), (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 #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 #undef FUNC_NAME
SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0, SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0,
(SCM obj), (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 #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 #undef FUNC_NAME
int int
scm_to_bool (SCM x) scm_to_bool (SCM x)
{ {
/* XXX Should this first test use scm_is_false_or_nil instead? */ if (scm_is_false (x))
if (scm_is_eq (x, SCM_BOOL_F))
return 0; return 0;
else if (scm_is_eq (x, SCM_BOOL_T)) else if (scm_is_eq (x, SCM_BOOL_T))
return 1; return 1;
@ -93,7 +92,7 @@ int
scm_is_bool (SCM obj) scm_is_bool (SCM obj)
{ {
/* This must match the macro definition of `scm_is_bool ()'. */ /* 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);
} }

11
libguile/boolean.h
View file

@ -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 #endif
#define scm_is_true_and_not_nil(x) (!scm_is_false_or_nil (x)) #define scm_is_true_and_not_nil(x) (!scm_is_false_or_nil (x))
/* XXX Should these macros treat %nil as false by default? */ /* %nil is false. */
#define scm_is_false(x) (scm_is_false_and_not_nil (x)) #define scm_is_false(x) (scm_is_false_or_nil (x))
#define scm_is_true(x) (!scm_is_false (x)) #define scm_is_true(x) (!scm_is_false (x))
/* /*
@ -90,8 +92,7 @@
SCM_API int scm_is_bool (SCM); 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_or_nil (x))
#define scm_is_bool(x) (scm_is_bool_and_not_nil (x))
#define scm_from_bool(x) ((x) ? SCM_BOOL_T : SCM_BOOL_F) #define scm_from_bool(x) ((x) ? SCM_BOOL_T : SCM_BOOL_F)
SCM_API int scm_to_bool (SCM x); SCM_API int scm_to_bool (SCM x);

4
libguile/vm-i-system.c
View file

@ -484,12 +484,12 @@ VM_DEFINE_INSTRUCTION (35, br, "br", 3, 0, 0)
VM_DEFINE_INSTRUCTION (36, br_if, "br-if", 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) 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) VM_DEFINE_INSTRUCTION (38, br_if_eq, "br-if-eq", 3, 0, 0)