So, finally, here we go with these patches.
Mark H Weaver <m...@netris.org> writes:
> Attached are patches to optimize %nil handling, along with some fixes
> to %nil-handling bugs, as I outlined in my recent posts.
>
> Four patches are attached. The first.patch is the most important, and
> is a prerequisite for the others. In brief it does the following:
>
> * Renumbers the IFLAG constants.
>
> * Adds several macros related to boolean type tests, null tests, and
> boolean-truth testing (including lisp-style boolean-truth tests).
>
> * Adds compile-time checks to verify the necessary IFLAG numbering
> properties needed for the checks to work properly.
>
> * Changes some existing code to use the new optimized macros, without
> changing the semantics of the code at all (except that scm_is_bool
> is changed from a function to a macro).
>
> I added the following macros, whose names explicitly state how %nil
> should be handled. See the comments in the patch for more information
> about these.
>
> scm_is_false_assume_not_lisp_nil scm_is_true_assume_not_lisp_nil
> scm_is_false_and_not_lisp_nil scm_is_true_or_lisp_nil
> scm_is_false_or_lisp_nil scm_is_true_and_not_lisp_nil
>
> scm_is_lisp_false scm_is_lisp_true
>
> scm_is_null_assume_not_lisp_nil
> scm_is_null_and_not_lisp_nil
> scm_is_null_or_lisp_nil
>
> scm_is_bool_and_not_lisp_nil
> scm_is_bool_or_lisp_nil
>
> The following already-existing macros are defined as aliases, such
> that their semantics is unchanged (although scm_is_bool used to be a
> function and is now a macro).
>
> scm_is_null --> scm_is_null_and_not_lisp_nil
> scm_is_false --> scm_is_false_and_not_lisp_nil
> scm_is_true --> scm_is_true_or_lisp_nil
> scm_is_bool --> scm_is_bool_and_not_lisp_nil
>
> (I still believe that these should be changed to versions that handle
> %nil properly, but await approval on that point, so these patches do
> not make those changes)
>
> Also, if the preprocessor macro SCM_ENABLE_ELISP is not true (this
> macro already existed and was used in lang.h), all overheads
> associated with %nil handling are eliminated from the above macros.
>
>
> vm-fixes.patch changes semantics, by fixing %nil handling in the
> following instructions: br-if, br-if-not, br-if-null, br-if-not-null,
> not, not-not, null?, and not-null?
>
> srfi-1-fixes.patch changes semantics, by fixing %nil handling in
> several functions. Note that this patch (and several other large
> forthcoming patches) will be unnecessary if the scm_is_false,
> scm_is_true, and scm_is_null macros are changed to handle %nil as I
> proposed.
>
> non-essential.patch is the last and least important. It doesn't
> change any functionality or implementation. It changes two
> occurrences of scm_is_bool and scm_is_null, in which %nil must *not*
> be treated as a boolean or null, to use newly-added equivalent macros
> which are explicit about how nil should be handled. These changes
> will be needed if scm_is_null is changed as I proposed. It also adds
> a few comments related to %nil handling.
>
> I've run "make check" on recent git master (c4b681fd) with these
> patches applied, and everything seems to work.
>
> I haven't yet run any benchmarks, because I'm not sure how to best do
> that. I doubt the changes will make any noticeable difference except
> possibly in C code which does a lot of tests which include %nil.
>
> Comments and suggestions solicited.
>
> Best,
> Mark
>
> diff --git a/libguile/tags.h b/libguile/tags.h
> index 3294533..25aea09 100644
> --- a/libguile/tags.h
> +++ b/libguile/tags.h
> @@ -516,12 +516,47 @@ enum scm_tc8_tags
> #define SCM_MAKIFLAG(n) SCM_MAKE_ITAG8 ((n), scm_tc8_flag)
> #define SCM_IFLAGNUM(n) (SCM_ITAG8_DATA (n))
>
> +/*
> + * IMPORTANT NOTE regarding IFLAG numbering!!!
> + *
> + * Several macros depend upon careful IFLAG numbering of SCM_BOOL_F,
> + * SCM_BOOL_T, SCM_ELISP_NIL, SCM_EOL, and the two SCM_XXX_*_DONT_USE
> + * constants. In particular:
> + *
> + * - SCM_BOOL_F and SCM_BOOL_T must differ in exactly one bit position.
> + * (used to implement scm_is_bool_and_not_lisp_nil, aka scm_is_bool)
> + *
> + * - SCM_ELISP_NIL and SCM_BOOL_F must differ in exactly one bit position.
> + * (used to implement scm_is_false_or_lisp_nil and
> + * scm_is_true_and_not_lisp_nil)
> + *
> + * - SCM_ELISP_NIL and SCM_EOL must differ in exactly one bit position.
> + * (used to implement scm_is_null_or_lisp_nil)
> + *
> + * - SCM_ELISP_NIL, SCM_BOOL_F, SCM_EOL, SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE
> + * must all be equal except for two bit positions.
> + * (used to implement scm_is_lisp_false)
> + *
> + * - SCM_ELISP_NIL, SCM_BOOL_F, SCM_BOOL_T, SCM_XXX_ANOTHER_BOOLEAN_DONT_USE
> + * must all be equal except for two bit positions.
> + * (used to implement scm_is_bool_or_lisp_nil)
> + *
> + * These properties allow the aforementioned macros to be implemented
> + * by bitwise ANDing with a mask and then comparing with a constant,
> + * using as a common basis the macro SCM_MATCHES_BITS_IN_COMMON,
> + * defined below. The properties are checked at compile-time using
> + * `verify' macros near the top of boolean.c and pairs.c.
> + */
Appreciate the detailed comments.
> #define SCM_BOOL_F SCM_MAKIFLAG (0)
> -#define SCM_BOOL_T SCM_MAKIFLAG (1)
> -#define SCM_UNDEFINED SCM_MAKIFLAG (2)
> -#define SCM_EOF_VAL SCM_MAKIFLAG (3)
> -#define SCM_EOL SCM_MAKIFLAG (4)
> -#define SCM_UNSPECIFIED SCM_MAKIFLAG (5)
> +#define SCM_ELISP_NIL SCM_MAKIFLAG (1)
> +#define SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE SCM_MAKIFLAG (2)
> +#define SCM_EOL SCM_MAKIFLAG (3)
> +#define SCM_BOOL_T SCM_MAKIFLAG (4)
> +#define SCM_XXX_ANOTHER_BOOLEAN_DONT_USE SCM_MAKIFLAG (5)
> +
> +#define SCM_UNSPECIFIED SCM_MAKIFLAG (6)
> +#define SCM_UNDEFINED SCM_MAKIFLAG (7)
> +#define SCM_EOF_VAL SCM_MAKIFLAG (8)
>
> /* When a variable is unbound this is marked by the SCM_UNDEFINED
> * value. The following is an unbound value which can be handled on
> @@ -531,14 +566,50 @@ enum scm_tc8_tags
> * the code which handles this value in C so that SCM_UNDEFINED can be
> * used instead. It is not ideal to let this kind of unique and
> * strange values loose on the Scheme level. */
> -#define SCM_UNBOUND SCM_MAKIFLAG (6)
> -
> -/* The Elisp nil value. */
> -#define SCM_ELISP_NIL SCM_MAKIFLAG (7)
> -
> +#define SCM_UNBOUND SCM_MAKIFLAG (9)
>
> #define SCM_UNBNDP(x) (scm_is_eq ((x), SCM_UNDEFINED))
>
> +/*
> + * SCM_MATCHES_BITS_IN_COMMON(x,a,b) returns 1 if and only if x
> + * matches both a and b in every bit position where a and b are equal;
> + * otherwise it returns 0. Bit positions where a and b differ are
> + * ignored.
> + *
> + * This is used to efficiently compare against two values which differ
> + * in exactly one bit position, or against four values which differ in
> + * exactly two bit positions. It is the basis for the following
> + * macros:
> + *
> + * scm_is_null_or_lisp_nil,
> + * scm_is_false_or_lisp_nil,
> + * scm_is_true_and_not_lisp_nil,
> + * scm_is_lisp_false,
> + * scm_is_lisp_true,
> + * scm_is_bool_and_not_lisp_nil (aka scm_is_bool)
> + * scm_is_bool_or_lisp_nil.
> + */
> +#define SCM_MATCHES_BITS_IN_COMMON(x,a,b) \
> + ((SCM_UNPACK(x) & ~(SCM_UNPACK(a) ^ SCM_UNPACK(b))) == \
> + (SCM_UNPACK(a) & SCM_UNPACK(b)))
> +
> +/*
> + * These macros are used for compile-time verification that the
> + * constants have the properties needed for the above macro to work
> + * properly.
> + */
> +#define SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED(x) ((x) & ((x)-1))
> +#define SCM_HAS_EXACTLY_ONE_BIT_SET(x)
> \
> + ((x) != 0 && SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED (x) == 0)
I know they're not needed, but I'd still add some more parentheses
here.
> +#define SCM_HAS_EXACTLY_TWO_BITS_SET(x)
> \
> + (SCM_HAS_EXACTLY_ONE_BIT_SET (SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED
> (x)))
> +
> +#define SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION(a,b) \
> + (SCM_HAS_EXACTLY_ONE_BIT_SET (SCM_UNPACK(a) ^ SCM_UNPACK(b)))
> +#define SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS(a,b,c,d)
> \
> + (SCM_HAS_EXACTLY_TWO_BITS_SET ((SCM_UNPACK(a) ^ SCM_UNPACK(b)) | \
> + (SCM_UNPACK(b) ^ SCM_UNPACK(c)) | \
> + (SCM_UNPACK(c) ^ SCM_UNPACK(d))))
>
I'd like to make it explicit that these macros are not part of the
public libguile API, and we recently agreed on using the
BUILDING_LIBGUILE macro to do this. So we just need to put #ifdef
BUILDING_LIBGUILE ... #endif around them.
> /* Evaluator byte codes ('immediate symbols'). These constants are used only
> diff --git a/libguile/print.c b/libguile/print.c
> index 6c44d59..fd65bf9 100644
> --- a/libguile/print.c
> +++ b/libguile/print.c
> @@ -61,18 +61,17 @@
> static const char *iflagnames[] =
> {
> "#f",
> + "#nil", /* Elisp nil value. Should print from elisp as symbol `nil'. */
> + "#<XXX_ANOTHER_LISP_FALSE_DONT_USE__SHOULD_NOT_EXIST!!>",
> + "()",
> "#t",
> + "#<XXX_ANOTHER_BOOLEAN_DONT_USE__SHOULD_NOT_EXIST!!>",
"SHOULD_NOT_EXIST" might make a future developer think that those
entries should removed from the code. Maybe add a comment to explain
what it really means, or change to "SHOULD_NEVER_BE_SEEN"?
> + "#<unspecified>",
> "#<undefined>",
> "#<eof>",
> - "()",
> - "#<unspecified>",
>
> /* Unbound slot marker for GOOPS. For internal use in GOOPS only. */
> "#<unbound>",
> -
> - /* Elisp nil value. This is its Scheme name; whenever it's printed in
> - * Elisp, it should appear as the symbol `nil'. */
> - "#nil"
> };
>
> SCM_SYMBOL (sym_reader, "reader");
> diff --git a/libguile/boolean.h b/libguile/boolean.h
> index 5a83797..2c480c0 100644
> --- a/libguile/boolean.h
> +++ b/libguile/boolean.h
> @@ -31,16 +31,97 @@
> *
> */
>
> +/*
> + * Use these macros if it's important (for correctness)
> + * that %nil MUST be considered true
> + */
> +#define scm_is_false_and_not_lisp_nil(x) (scm_is_eq ((x), SCM_BOOL_F))
> +#define scm_is_true_or_lisp_nil(x) (!scm_is_eq ((x), SCM_BOOL_F))
> +
> +/*
> + * Use these macros if %nil will never be tested,
> + * for increased efficiency.
> + */
> +#define scm_is_false_assume_not_lisp_nil(x) (scm_is_eq ((x), SCM_BOOL_F))
> +#define scm_is_true_assume_not_lisp_nil(x) (!scm_is_eq ((x), SCM_BOOL_F))
> +
> +/*
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information on
> + * how the following macro works.
> + */
> +#if SCM_ENABLE_ELISP
> +# define scm_is_false_or_lisp_nil(x) \
> + (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_ELISP_NIL, SCM_BOOL_F))
> +#else
> +# define scm_is_false_or_lisp_nil(x) (scm_is_false_assume_not_lisp_nil
> (x))
> +#endif
> +#define scm_is_true_and_not_lisp_nil(x) (!scm_is_false_or_lisp_nil (x))
>
> -#define scm_is_false(x) scm_is_eq ((x), SCM_BOOL_F)
> -#define scm_is_true(x) !scm_is_false (x)
> +/* XXX Should these macros treat %nil as false by default? */
> +#define scm_is_false(x) (scm_is_false_and_not_lisp_nil (x))
> +#define scm_is_true(x) (!scm_is_false (x))
> +
> +/*
> + * Since we know SCM_BOOL_F and SCM_BOOL_T differ by exactly one bit,
> + * and that SCM_BOOL_F and SCM_ELISP_NIL differ by exactly one bit,
> + * and that they of course can't be the same bit (or else SCM_BOOL_T
> + * and SCM_ELISP_NIL be would equal), it follows that SCM_BOOL_T and
> + * SCM_ELISP_NIL differ by exactly two bits, and these are the bits
> + * which will be ignored by SCM_MATCHES_BITS_IN_COMMON below.
> + *
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
> + *
> + * If SCM_ENABLE_ELISP is true, then scm_is_bool_or_lisp_nil(x)
> + * returns 1 if and only if x is one of the following: SCM_BOOL_F,
> + * SCM_BOOL_T, SCM_ELISP_NIL, or SCM_XXX_ANOTHER_BOOLEAN_DONT_USE.
> + * Otherwise, it returns 0.
> + */
> +#if SCM_ENABLE_ELISP
> +# define scm_is_bool_or_lisp_nil(x) \
> + (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_T, SCM_ELISP_NIL))
> +#else
> +# define scm_is_bool_or_lisp_nil(x) (scm_is_bool_and_not_lisp_nil (x))
> +#endif
> +
> +#define scm_is_bool_and_not_lisp_nil(x) \
> + (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_F, SCM_BOOL_T))
> +
> +/* XXX Should scm_is_bool treat %nil as a boolean? */
> +#define scm_is_bool(x) (scm_is_bool_and_not_lisp_nil (x))
>
> -SCM_API int scm_is_bool (SCM x);
> #define scm_from_bool(x) ((x) ? SCM_BOOL_T : SCM_BOOL_F)
> SCM_API int scm_to_bool (SCM x);
>
>
>
> +/*
> + * The following macros efficiently implement boolean truth testing as
> + * expected by most lisps, which treat '() aka SCM_EOL as false.
> + *
> + * Since we know SCM_ELISP_NIL and SCM_BOOL_F differ by exactly one
> + * bit, and that SCM_ELISP_NIL and SCM_EOL differ by exactly one bit,
> + * and that they of course can't be the same bit (or else SCM_BOOL_F
> + * and SCM_EOL be would equal), it follows that SCM_BOOL_F and SCM_EOL
> + * differ by exactly two bits, and these are the bits which will be
> + * ignored by SCM_MATCHES_BITS_IN_COMMON below.
> + *
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
> + *
> + * scm_is_lisp_false(x) returns 1 if and only if x is one of the
> + * following: SCM_BOOL_F, SCM_ELISP_NIL, SCM_EOL or
> + * SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE. Otherwise, it returns 0.
> + */
> +#if SCM_ENABLE_ELISP
> +# define scm_is_lisp_false(x) \
> + (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_BOOL_F, SCM_EOL))
> +# define scm_is_lisp_true(x) (!scm_is_lisp_false(x))
> +#endif
> +
> +
> +
> SCM_API SCM scm_not (SCM x);
> SCM_API SCM scm_boolean_p (SCM obj);
>
> diff --git a/libguile/boolean.c b/libguile/boolean.c
> index d79bf79..9a4f896 100644
> --- a/libguile/boolean.c
> +++ b/libguile/boolean.c
> @@ -29,15 +29,37 @@
> #include "libguile/lang.h"
> #include "libguile/tags.h"
>
> +#include "verify.h"
> +
>
>
> +/*
> + * These compile-time tests verify the properties needed for the
> + * efficient test macros defined in boolean.h, which are defined in
> + * terms of the SCM_MATCHES_BITS_IN_COMMON macro.
> + *
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
> + */
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
> + (SCM_BOOL_F, SCM_BOOL_T));
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
> + (SCM_ELISP_NIL, SCM_BOOL_F));
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
> + (SCM_ELISP_NIL, SCM_EOL));
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
> + (SCM_ELISP_NIL, SCM_BOOL_F, SCM_BOOL_T, \
> + SCM_XXX_ANOTHER_BOOLEAN_DONT_USE));
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS \
> + (SCM_ELISP_NIL, SCM_BOOL_F, SCM_EOL, \
> + SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE));
>
> SCM_DEFINE (scm_not, "not", 1, 0, 0,
> (SCM x),
> "Return @code{#t} iff @var{x} is @code{#f}, else return
> @code{#f}.")
> #define FUNC_NAME s_scm_not
> {
> - return scm_from_bool (scm_is_false (x) || SCM_NILP (x));
> + return scm_from_bool (scm_is_false_or_lisp_nil (x));
> }
> #undef FUNC_NAME
>
> @@ -47,19 +69,14 @@ SCM_DEFINE (scm_boolean_p, "boolean?", 1, 0, 0,
> "Return @code{#t} iff @var{obj} is either @code{#t} or
> @code{#f}.")
> #define FUNC_NAME s_scm_boolean_p
> {
> - return scm_from_bool (scm_is_bool (obj) || SCM_NILP (obj));
> + return scm_from_bool (scm_is_bool_or_lisp_nil (obj));
> }
> #undef FUNC_NAME
>
> int
> -scm_is_bool (SCM x)
> -{
> - return scm_is_eq (x, SCM_BOOL_F) || scm_is_eq (x, SCM_BOOL_T);
> -}
> -
> -int
> scm_to_bool (SCM x)
> {
> + /* XXX Should this first test use scm_is_false_or_lisp_nil instead? */
> if (scm_is_eq (x, SCM_BOOL_F))
> return 0;
> else if (scm_is_eq (x, SCM_BOOL_T))
> diff --git a/libguile/pairs.h b/libguile/pairs.h
> index a6d44d2..9c75709 100644
> --- a/libguile/pairs.h
> +++ b/libguile/pairs.h
> @@ -34,7 +34,32 @@
> # define SCM_VALIDATE_PAIR(cell, expr) (expr)
> #endif
>
> -#define scm_is_null(x) (scm_is_eq ((x), SCM_EOL))
> +/*
> + * Use scm_is_null_and_not_lisp_nil if it's important (for correctness)
> + * that %nil must NOT be considered null.
> + */
> +#define scm_is_null_and_not_lisp_nil(x) (scm_is_eq ((x), SCM_EOL))
> +
> +/*
> + * Use scm_is_null_assume_not_lisp_nil if %nil will never be tested,
> + * for increased efficiency.
> + */
> +#define scm_is_null_assume_not_lisp_nil(x) (scm_is_eq ((x), SCM_EOL))
> +
> +/*
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information on
> + * how the following macro works.
> + */
> +#if SCM_ENABLE_ELISP
> +# define scm_is_null_or_lisp_nil(x) \
> + (SCM_MATCHES_BITS_IN_COMMON ((x), SCM_ELISP_NIL, SCM_EOL))
> +#else
> +# define scm_is_null_or_lisp_nil(x) (scm_is_null_assume_not_lisp_nil (x))
> +#endif
> +
> +/* XXX Should scm_is_null treat %nil as null by default? */
> +#define scm_is_null(x) (scm_is_null_and_not_lisp_nil(x))
>
> #define SCM_CAR(x) (SCM_VALIDATE_PAIR (x, SCM_CELL_OBJECT_0 (x)))
> #define SCM_CDR(x) (SCM_VALIDATE_PAIR (x, SCM_CELL_OBJECT_1 (x)))
> diff --git a/libguile/pairs.c b/libguile/pairs.c
> index aaaeb11..49eef82 100644
> --- a/libguile/pairs.c
> +++ b/libguile/pairs.c
> @@ -27,11 +27,25 @@
>
> #include "libguile/pairs.h"
>
> +#include "verify.h"
> +
>
>
> /* {Pairs}
> */
>
> +/*
> + * This compile-time test verifies the properties needed for the
> + * efficient test macro scm_is_null_or_lisp_nil defined in pairs.h,
> + * which is defined in terms of the SCM_MATCHES_BITS_IN_COMMON macro.
> + *
> + * See the comments preceeding the definitions of SCM_BOOL_F and
> + * SCM_MATCHES_BITS_IN_COMMON in tags.h for more information.
> + */
> +verify (SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION \
> + (SCM_ELISP_NIL, SCM_EOL));
> +
> +
> #if (SCM_DEBUG_PAIR_ACCESSES == 1)
>
> #include "libguile/ports.h"
> diff --git a/libguile/lang.h b/libguile/lang.h
> index 47128de..985f5ef 100644
> --- a/libguile/lang.h
> +++ b/libguile/lang.h
> @@ -39,7 +39,7 @@ SCM_INTERNAL void scm_init_lang (void);
>
> #endif /* ! SCM_ENABLE_ELISP */
>
> -#define SCM_NULL_OR_NIL_P(x) (scm_is_null (x) || SCM_NILP (x))
> +#define SCM_NULL_OR_NIL_P(x) (scm_is_null_or_lisp_nil (x))
>
> #endif /* SCM_LANG_H */
>
> diff --git a/libguile/eval.i.c b/libguile/eval.i.c
> index 99aa265..9da1664 100644
> --- a/libguile/eval.i.c
> +++ b/libguile/eval.i.c
> @@ -304,7 +304,7 @@ dispatch:
> while (!scm_is_null (SCM_CDR (x)))
> {
> SCM test_result = EVALCAR (x, env);
> - if (scm_is_false (test_result) || SCM_NILP (test_result))
> + if (scm_is_false_or_lisp_nil (test_result))
> RETURN (SCM_BOOL_F);
> else
> x = SCM_CDR (x);
> @@ -442,8 +442,7 @@ dispatch:
> xx = SCM_CDR (clause);
> proc = EVALCAR (xx, env);
> guard_result = SCM_APPLY (proc, arg1, SCM_EOL);
> - if (scm_is_true (guard_result)
> - && !SCM_NILP (guard_result))
> + if (scm_is_true_and_not_lisp_nil (guard_result))
> {
> proc = SCM_CDDR (xx);
> proc = EVALCAR (proc, env);
> @@ -451,7 +450,7 @@ dispatch:
> goto apply_proc;
> }
> }
> - else if (scm_is_true (arg1) && !SCM_NILP (arg1))
> + else if (scm_is_true_and_not_lisp_nil (arg1))
> {
> x = SCM_CDR (clause);
> if (scm_is_null (x))
> @@ -498,7 +497,7 @@ dispatch:
>
> SCM test_result = EVALCAR (test_form, env);
>
> - while (scm_is_false (test_result) || SCM_NILP (test_result))
> + while (scm_is_false_or_lisp_nil (test_result))
> {
> {
> /* Evaluate body forms. */
> @@ -552,7 +551,7 @@ dispatch:
> {
> SCM test_result = EVALCAR (x, env);
> x = SCM_CDR (x); /* then expression */
> - if (scm_is_false (test_result) || SCM_NILP (test_result))
> + if (scm_is_false_or_lisp_nil (test_result))
> {
> x = SCM_CDR (x); /* else expression */
> if (scm_is_null (x))
> @@ -623,7 +622,7 @@ dispatch:
> while (!scm_is_null (SCM_CDR (x)))
> {
> SCM val = EVALCAR (x, env);
> - if (scm_is_true (val) && !SCM_NILP (val))
> + if (scm_is_true_and_not_lisp_nil (val))
> RETURN (val);
> else
> x = SCM_CDR (x);
>
> diff --git a/libguile/vm-i-system.c b/libguile/vm-i-system.c
> index d55d6e2..427a2fc 100644
> --- a/libguile/vm-i-system.c
> +++ b/libguile/vm-i-system.c
> @@ -406,12 +406,12 @@ VM_DEFINE_INSTRUCTION (31, br, "br", 2, 0, 0)
>
> VM_DEFINE_INSTRUCTION (32, br_if, "br-if", 2, 0, 0)
> {
> - BR (!SCM_FALSEP (*sp));
> + BR (scm_is_true_and_not_lisp_nil (*sp));
> }
>
> VM_DEFINE_INSTRUCTION (33, br_if_not, "br-if-not", 2, 0, 0)
> {
> - BR (SCM_FALSEP (*sp));
> + BR (scm_is_false_or_lisp_nil (*sp));
> }
>
> VM_DEFINE_INSTRUCTION (34, br_if_eq, "br-if-eq", 2, 0, 0)
> @@ -428,12 +428,12 @@ VM_DEFINE_INSTRUCTION (35, br_if_not_eq,
> "br-if-not-eq", 2, 0, 0)
>
> VM_DEFINE_INSTRUCTION (36, br_if_null, "br-if-null", 2, 0, 0)
> {
> - BR (SCM_NULLP (*sp));
> + BR (scm_is_null_or_lisp_nil (*sp));
> }
>
> VM_DEFINE_INSTRUCTION (37, br_if_not_null, "br-if-not-null", 2, 0, 0)
> {
> - BR (!SCM_NULLP (*sp));
> + BR (!scm_is_null_or_lisp_nil (*sp));
> }
>
>
> diff --git a/libguile/vm-i-scheme.c b/libguile/vm-i-scheme.c
> index 5de39a2..40781ff 100644
> --- a/libguile/vm-i-scheme.c
> +++ b/libguile/vm-i-scheme.c
> @@ -32,13 +32,13 @@
> VM_DEFINE_FUNCTION (80, not, "not", 1)
> {
> ARGS1 (x);
> - RETURN (SCM_BOOL (SCM_FALSEP (x)));
> + RETURN (SCM_BOOL (scm_is_false_or_lisp_nil (x)));
> }
>
> VM_DEFINE_FUNCTION (81, not_not, "not-not", 1)
> {
> ARGS1 (x);
> - RETURN (SCM_BOOL (!SCM_FALSEP (x)));
> + RETURN (SCM_BOOL (!scm_is_false_or_lisp_nil (x)));
> }
>
> VM_DEFINE_FUNCTION (82, eq, "eq?", 2)
> @@ -56,13 +56,13 @@ VM_DEFINE_FUNCTION (83, not_eq, "not-eq?", 2)
> VM_DEFINE_FUNCTION (84, nullp, "null?", 1)
> {
> ARGS1 (x);
> - RETURN (SCM_BOOL (SCM_NULLP (x)));
> + RETURN (SCM_BOOL (scm_is_null_or_lisp_nil (x)));
> }
>
> VM_DEFINE_FUNCTION (85, not_nullp, "not-null?", 1)
> {
> ARGS1 (x);
> - RETURN (SCM_BOOL (!SCM_NULLP (x)));
> + RETURN (SCM_BOOL (!scm_is_null_or_lisp_nil (x)));
> }
>
> VM_DEFINE_FUNCTION (86, eqv, "eqv?", 2)
>
> diff --git a/srfi/srfi-1.c b/srfi/srfi-1.c
> index 02f46fc..268f1dc 100644
> --- a/srfi/srfi-1.c
> +++ b/srfi/srfi-1.c
> @@ -211,7 +211,7 @@ SCM_DEFINE (scm_srfi1_break, "break", 2, 0, 0,
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> SCM elem = SCM_CAR (lst);
> - if (scm_is_true (pred_tramp (pred, elem)))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, elem)))
> goto done;
>
> /* want this elem, tack it onto the end of ret */
> @@ -243,7 +243,7 @@ SCM_DEFINE (scm_srfi1_break_x, "break!", 2, 0, 0,
> p = &lst;
> for (upto = lst; scm_is_pair (upto); upto = SCM_CDR (upto))
> {
> - if (scm_is_true (pred_tramp (pred, SCM_CAR (upto))))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, SCM_CAR (upto))))
> goto done;
>
> /* want this element */
> @@ -334,7 +334,8 @@ SCM_DEFINE (scm_srfi1_count, "count", 2, 0, 1,
> SCM_ASSERT (pred_tramp, pred, SCM_ARG1, FUNC_NAME);
>
> for ( ; scm_is_pair (list1); list1 = SCM_CDR (list1))
> - count += scm_is_true (pred_tramp (pred, SCM_CAR (list1)));
> + count += scm_is_true_and_not_lisp_nil (pred_tramp (pred,
> + SCM_CAR (list1)));
>
> /* check below that list1 is a proper list, and done */
> end_list1:
> @@ -361,8 +362,9 @@ SCM_DEFINE (scm_srfi1_count, "count", 2, 0, 1,
> argnum = 3;
> break;
> }
> - count += scm_is_true (pred_tramp
> - (pred, SCM_CAR (list1), SCM_CAR (list2)));
> + count += scm_is_true_and_not_lisp_nil (pred_tramp
> + (pred, SCM_CAR (list1),
> + SCM_CAR (list2)));
> list1 = SCM_CDR (list1);
> list2 = SCM_CDR (list2);
> }
> @@ -396,7 +398,8 @@ SCM_DEFINE (scm_srfi1_count, "count", 2, 0, 1,
> SCM_SIMPLE_VECTOR_SET (vec, i, SCM_CDR (lst)); /* rest of lst
> */
> }
>
> - count += scm_is_true (scm_apply (pred, args, SCM_EOL));
> + count += scm_is_true_and_not_lisp_nil (scm_apply (pred, args,
> + SCM_EOL));
> }
> }
>
> @@ -452,7 +455,7 @@ SCM_DEFINE (scm_srfi1_delete, "delete", 2, 1, 0,
>
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> - if (scm_is_true (equal_p (pred, x, SCM_CAR (lst))))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, x, SCM_CAR (lst))))
> {
> /* delete this element, so copy those at keeplst */
> p = list_copy_part (keeplst, count, p);
> @@ -509,7 +512,7 @@ SCM_DEFINE (scm_srfi1_delete_x, "delete!", 2, 1, 0,
> scm_is_pair (walk);
> walk = SCM_CDR (walk))
> {
> - if (scm_is_true (equal_p (pred, x, SCM_CAR (walk))))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, x, SCM_CAR (walk))))
> *prev = SCM_CDR (walk);
> else
> prev = SCM_CDRLOC (walk);
> @@ -591,7 +594,7 @@ SCM_DEFINE (scm_srfi1_delete_duplicates,
> "delete-duplicates", 1, 1, 0,
> /* look for item in "ret" list */
> for (l = ret; scm_is_pair (l); l = SCM_CDR (l))
> {
> - if (scm_is_true (equal_p (pred, SCM_CAR (l), item)))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, SCM_CAR (l),
> item)))
> {
> /* "item" is a duplicate, so copy keeplst onto ret */
> duplicate:
> @@ -608,7 +611,7 @@ SCM_DEFINE (scm_srfi1_delete_duplicates,
> "delete-duplicates", 1, 1, 0,
> for (i = 0, l = keeplst;
> i < count && scm_is_pair (l);
> i++, l = SCM_CDR (l))
> - if (scm_is_true (equal_p (pred, SCM_CAR (l), item)))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, SCM_CAR (l), item)))
> goto duplicate;
>
> /* keep this element */
> @@ -684,7 +687,8 @@ SCM_DEFINE (scm_srfi1_delete_duplicates_x,
> "delete-duplicates!", 1, 1, 0,
> l = ret;
> for (;;)
> {
> - if (scm_is_true (equal_p (pred, SCM_CAR (l), item)))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, SCM_CAR (l),
> + item)))
> break; /* equal, forget this element */
>
> if (scm_is_eq (l, endret))
> @@ -770,7 +774,7 @@ SCM_DEFINE (scm_srfi1_drop_while, "drop-while", 2, 0, 0,
> SCM_ASSERT (pred_tramp, pred, SCM_ARG1, FUNC_NAME);
>
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> - if (scm_is_false (pred_tramp (pred, SCM_CAR (lst))))
> + if (scm_is_false_or_lisp_nil (pred_tramp (pred, SCM_CAR (lst))))
> goto done;
>
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME,
> "list");
> @@ -824,7 +828,7 @@ SCM_DEFINE (scm_srfi1_filter_map, "filter-map", 2, 0, 1,
> for ( ; scm_is_pair (list1); list1 = SCM_CDR (list1))
> {
> elem = proc_tramp (proc, SCM_CAR (list1));
> - if (scm_is_true (elem))
> + if (scm_is_true_and_not_lisp_nil (elem))
> {
> newcell = scm_cons (elem, SCM_EOL);
> *loc = newcell;
> @@ -855,7 +859,7 @@ SCM_DEFINE (scm_srfi1_filter_map, "filter-map", 2, 0, 1,
> goto check_lst_and_done;
> }
> elem = proc_tramp (proc, SCM_CAR (list1), SCM_CAR (list2));
> - if (scm_is_true (elem))
> + if (scm_is_true_and_not_lisp_nil (elem))
> {
> newcell = scm_cons (elem, SCM_EOL);
> *loc = newcell;
> @@ -895,7 +899,7 @@ SCM_DEFINE (scm_srfi1_filter_map, "filter-map", 2, 0, 1,
> }
>
> elem = scm_apply (proc, args, SCM_EOL);
> - if (scm_is_true (elem))
> + if (scm_is_true_and_not_lisp_nil (elem))
> {
> newcell = scm_cons (elem, SCM_EOL);
> *loc = newcell;
> @@ -924,7 +928,7 @@ SCM_DEFINE (scm_srfi1_find, "find", 2, 0, 0,
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> SCM elem = SCM_CAR (lst);
> - if (scm_is_true (pred_tramp (pred, elem)))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, elem)))
> return elem;
> }
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME,
> "list");
> @@ -945,7 +949,7 @@ SCM_DEFINE (scm_srfi1_find_tail, "find-tail", 2, 0, 0,
> SCM_ASSERT (pred_tramp, pred, SCM_ARG1, FUNC_NAME);
>
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> - if (scm_is_true (pred_tramp (pred, SCM_CAR (lst))))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, SCM_CAR (lst))))
> return lst;
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME,
> "list");
>
> @@ -1121,7 +1125,7 @@ SCM_DEFINE (scm_srfi1_list_index, "list-index", 2, 0, 1,
> SCM_ASSERT (pred_tramp, pred, SCM_ARG1, FUNC_NAME);
>
> for ( ; scm_is_pair (list1); n++, list1 = SCM_CDR (list1))
> - if (scm_is_true (pred_tramp (pred, SCM_CAR (list1))))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, SCM_CAR
> (list1))))
> return SCM_I_MAKINUM (n);
>
> /* not found, check below that list1 is a proper list */
> @@ -1146,8 +1150,9 @@ SCM_DEFINE (scm_srfi1_list_index, "list-index", 2, 0, 1,
> argnum = 3;
> break;
> }
> - if (scm_is_true (pred_tramp (pred,
> - SCM_CAR (list1), SCM_CAR (list2))))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred,
> + SCM_CAR (list1),
> + SCM_CAR (list2))))
> return SCM_I_MAKINUM (n);
>
> list1 = SCM_CDR (list1);
> @@ -1183,7 +1188,7 @@ SCM_DEFINE (scm_srfi1_list_index, "list-index", 2, 0, 1,
> SCM_SIMPLE_VECTOR_SET (vec, i, SCM_CDR (lst)); /* rest of lst
> */
> }
>
> - if (scm_is_true (scm_apply (pred, args, SCM_EOL)))
> + if (scm_is_true_and_not_lisp_nil (scm_apply (pred, args, SCM_EOL)))
> return SCM_I_MAKINUM (n);
> }
> }
> @@ -1286,7 +1291,8 @@ SCM_DEFINE (scm_srfi1_lset_adjoin, "lset-adjoin", 2, 0,
> 1,
> elem = SCM_CAR (rest);
>
> for (l = lst; scm_is_pair (l); l = SCM_CDR (l))
> - if (scm_is_true (equal_tramp (equal, SCM_CAR (l), elem)))
> + if (scm_is_true_and_not_lisp_nil (equal_tramp (equal, SCM_CAR (l),
> + elem)))
> goto next_elem; /* elem already in lst, don't add */
>
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P(l), lst, SCM_ARG2, FUNC_NAME,
> "list");
> @@ -1343,7 +1349,8 @@ SCM_DEFINE (scm_srfi1_lset_difference_x,
> "lset-difference!", 2, 0, 1,
> r = SCM_CDR (r), argnum++)
> {
> for (b = SCM_CAR (r); scm_is_pair (b); b = SCM_CDR (b))
> - if (scm_is_true (equal_tramp (equal, elem, SCM_CAR (b))))
> + if (scm_is_true_and_not_lisp_nil (equal_tramp (equal, elem,
> + SCM_CAR (b))))
> goto next_elem; /* equal to elem, so drop that elem */
>
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (b), b, argnum,
> FUNC_NAME,"list");
> @@ -1385,7 +1392,7 @@ check_map_args (SCM argv,
> long elt_len;
> elt = SCM_SIMPLE_VECTOR_REF (argv, i);
>
> - if (!(scm_is_null (elt) || scm_is_pair (elt)))
> + if (!(scm_is_null_or_lisp_nil (elt) || scm_is_pair (elt)))
> goto check_map_error;
>
> elt_len = srfi1_ilength (elt);
> @@ -1430,7 +1437,8 @@ scm_srfi1_map (SCM proc, SCM arg1, SCM args)
> SCM *pres = &res;
>
> len = srfi1_ilength (arg1);
> - SCM_GASSERTn ((scm_is_null (arg1) || scm_is_pair (arg1)) && len >= -1,
> + SCM_GASSERTn ((scm_is_null_or_lisp_nil (arg1) ||
> + scm_is_pair (arg1)) && len >= -1,
> g_srfi1_map,
> scm_cons2 (proc, arg1, args), SCM_ARG2, s_srfi1_map);
> SCM_VALIDATE_REST_ARGUMENT (args);
> @@ -1456,7 +1464,7 @@ scm_srfi1_map (SCM proc, SCM arg1, SCM args)
> scm_cons2 (proc, arg1, args), SCM_ARG1, s_srfi1_map);
> if (len < 0 || (len2 >= 0 && len2 < len))
> len = len2;
> - SCM_GASSERTn ((scm_is_null (arg2) || scm_is_pair (arg2))
> + SCM_GASSERTn ((scm_is_null_or_lisp_nil (arg2) || scm_is_pair (arg2))
> && len >= 0 && len2 >= -1,
> g_srfi1_map,
> scm_cons2 (proc, arg1, args),
> @@ -1501,7 +1509,8 @@ scm_srfi1_for_each (SCM proc, SCM arg1, SCM args)
> {
> long i, len;
> len = srfi1_ilength (arg1);
> - SCM_GASSERTn ((scm_is_null (arg1) || scm_is_pair (arg1)) && len >= -1,
> + SCM_GASSERTn ((scm_is_null_or_lisp_nil (arg1) ||
> + scm_is_pair (arg1)) && len >= -1,
> g_srfi1_for_each, scm_cons2 (proc, arg1, args),
> SCM_ARG2, s_srfi1_for_each);
> SCM_VALIDATE_REST_ARGUMENT (args);
> @@ -1528,7 +1537,7 @@ scm_srfi1_for_each (SCM proc, SCM arg1, SCM args)
> scm_cons2 (proc, arg1, args), SCM_ARG1, s_srfi1_for_each);
> if (len < 0 || (len2 >= 0 && len2 < len))
> len = len2;
> - SCM_GASSERTn ((scm_is_null (arg2) || scm_is_pair (arg2))
> + SCM_GASSERTn ((scm_is_null_or_lisp_nil (arg2) || scm_is_pair (arg2))
> && len >= 0 && len2 >= -1,
> g_srfi1_for_each,
> scm_cons2 (proc, arg1, args),
> @@ -1593,7 +1602,7 @@ SCM_DEFINE (scm_srfi1_member, "member", 2, 1, 0,
> }
> for (; !SCM_NULL_OR_NIL_P (lst); lst = SCM_CDR (lst))
> {
> - if (scm_is_true (equal_p (pred, x, SCM_CAR (lst))))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, x, SCM_CAR (lst))))
> return lst;
> }
> return SCM_BOOL_F;
> @@ -1621,7 +1630,7 @@ SCM_DEFINE (scm_srfi1_assoc, "assoc", 2, 1, 0,
> SCM tmp = SCM_CAR (ls);
> SCM_ASSERT_TYPE (scm_is_pair (tmp), alist, SCM_ARG2, FUNC_NAME,
> "association list");
> - if (scm_is_true (equal_p (pred, key, SCM_CAR (tmp))))
> + if (scm_is_true_and_not_lisp_nil (equal_p (pred, key, SCM_CAR (tmp))))
> return tmp;
> }
> SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (ls), alist, SCM_ARG2, FUNC_NAME,
> @@ -1685,7 +1694,7 @@ SCM_DEFINE (scm_srfi1_partition, "partition", 2, 0, 0,
> elt = SCM_CAR (list);
> new_tail = scm_cons (SCM_CAR (list), SCM_EOL);
>
> - if (scm_is_true (call (pred, elt))) {
> + if (scm_is_true_and_not_lisp_nil (call (pred, elt))) {
> SCM_SETCDR(kept_tail, new_tail);
> kept_tail = new_tail;
> }
> @@ -1737,7 +1746,7 @@ SCM_DEFINE (scm_srfi1_partition_x, "partition!", 2, 0,
> 0,
>
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> - if (scm_is_true (pred_tramp (pred, SCM_CAR (lst))))
> + if (scm_is_true_and_not_lisp_nil (pred_tramp (pred, SCM_CAR (lst))))
> {
> *tp = lst;
> tp = SCM_CDRLOC (lst);
> @@ -1906,7 +1915,7 @@ SCM_DEFINE (scm_srfi1_remove, "remove", 2, 0, 0,
> scm_is_pair (walk);
> walk = SCM_CDR (walk))
> {
> - if (scm_is_false (call (pred, SCM_CAR (walk))))
> + if (scm_is_false_or_lisp_nil (call (pred, SCM_CAR (walk))))
> {
> *prev = scm_cons (SCM_CAR (walk), SCM_EOL);
> prev = SCM_CDRLOC (*prev);
> @@ -1938,7 +1947,7 @@ SCM_DEFINE (scm_srfi1_remove_x, "remove!", 2, 0, 0,
> scm_is_pair (walk);
> walk = SCM_CDR (walk))
> {
> - if (scm_is_false (call (pred, SCM_CAR (walk))))
> + if (scm_is_false_or_lisp_nil (call (pred, SCM_CAR (walk))))
> prev = SCM_CDRLOC (walk);
> else
> *prev = SCM_CDR (walk);
> @@ -1987,7 +1996,7 @@ SCM_DEFINE (scm_srfi1_span, "span", 2, 0, 0,
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> SCM elem = SCM_CAR (lst);
> - if (scm_is_false (pred_tramp (pred, elem)))
> + if (scm_is_false_or_lisp_nil (pred_tramp (pred, elem)))
> goto done;
>
> /* want this elem, tack it onto the end of ret */
> @@ -2019,7 +2028,7 @@ SCM_DEFINE (scm_srfi1_span_x, "span!", 2, 0, 0,
> p = &lst;
> for (upto = lst; scm_is_pair (upto); upto = SCM_CDR (upto))
> {
> - if (scm_is_false (pred_tramp (pred, SCM_CAR (upto))))
> + if (scm_is_false_or_lisp_nil (pred_tramp (pred, SCM_CAR (upto))))
> goto done;
>
> /* want this element */
> @@ -2147,7 +2156,7 @@ SCM_DEFINE (scm_srfi1_take_while, "take-while", 2, 0, 0,
> for ( ; scm_is_pair (lst); lst = SCM_CDR (lst))
> {
> SCM elem = SCM_CAR (lst);
> - if (scm_is_false (pred_tramp (pred, elem)))
> + if (scm_is_false_or_lisp_nil (pred_tramp (pred, elem)))
> goto done;
>
> /* want this elem, tack it onto the end of ret */
> @@ -2178,7 +2187,7 @@ SCM_DEFINE (scm_srfi1_take_while_x, "take-while!", 2,
> 0, 0,
> p = &lst;
> for (upto = lst; scm_is_pair (upto); upto = SCM_CDR (upto))
> {
> - if (scm_is_false (pred_tramp (pred, SCM_CAR (upto))))
> + if (scm_is_false_or_lisp_nil (pred_tramp (pred, SCM_CAR (upto))))
> goto done;
>
> /* want this element */
>
> diff --git a/libguile/discouraged.h b/libguile/discouraged.h
> index 1be05f0..0411069 100644
> --- a/libguile/discouraged.h
> +++ b/libguile/discouraged.h
> @@ -54,6 +54,9 @@
>
> /* SCM_BOOL_NOT returns the other boolean.
> * The order of ^s here is important for Borland C++ (!?!?!)
> + *
> + * XXX Should this handle %nil properly, and thus be
> + * defined as (scm_from_bool (scm_is_false_or_lisp_nil (x))) ?
> */
> #define SCM_BOOL_NOT(x) (SCM_PACK (SCM_UNPACK (x) \
> ^ (SCM_UNPACK (SCM_BOOL_T) \
> diff --git a/libguile/goops.c b/libguile/goops.c
> index 1548472..b6234a6 100644
> --- a/libguile/goops.c
> +++ b/libguile/goops.c
> @@ -190,11 +190,12 @@ SCM_DEFINE (scm_class_of, "class-of", 1, 0, 0,
> return scm_class_integer;
>
> case scm_tc3_imm24:
> + /* XXX What should be done with SCM_ELISP_NIL? */
> if (SCM_CHARP (x))
> return scm_class_char;
> - else if (scm_is_bool (x))
> + else if (scm_is_bool_and_not_lisp_nil (x))
> return scm_class_boolean;
> - else if (scm_is_null (x))
> + else if (scm_is_null_and_not_lisp_nil (x))
> return scm_class_null;
> else
> return scm_class_unknown;
