sql-null�� The sql-null extension implements the following interface.�� (sql-null)�� Return an object, corresponding to a SQL NULL value. The object is�� guaranteed to be of a type disjoint from all of the R5RS' standard�� types.�� It's unspecified whether the values returned by this function will�� be `eq?' to each other:�� (eq? (sql-null) (sql-null))�� => unspecified.�� (sql-null? OBJECT)�� Return #t if OBJECT is a SQL NULL object. Return #f otherwise.�� (sql-not OBJECT)�� Return OBJECT if OBJECT is a SQL NULL object. Return the value�� of `(not OBJECT)' otherwise.�� (sql-not (sql-null)) => SQL NULL;�� (sql-not 'a) => #f;�� (sql-not #f) => #t;�� (let ((null (sql-null)))�� (eq? null (sql-not null)))�� => #t.�� Syntax: (sql-and TEST-1 ...)�� The TEST expressions are evaluated from left to right, and the value�� of the first expression that evaluates to a false value is returned,�� and any remaining TESTs are not evaluated.�� If there were no expressions to evaluate to a false value, the value�� of any of the expressions to evaluate to a SQL NULL is returned. If�� there were no such expressions as well, #t is returned.�� (sql-and 1) => 1;�� (sql-and #t (sql-null))�� => SQL NULL;�� (sql-and #f (sql-null))�� => #f.�� In the absence of the expressions that evaluate to SQL NULL values,�� the semantics is the same as for `(and test-1 ...)'.�� Syntax: (sql-or test-1 ...)�� The TEST expressions are evaluated from left to right, and the�� value of the first expression that evaluates to a value, other�� than SQL NULL and a false value (a ``SQL true'' value), is�� returned, and any remaining TESTs are not evaluated.�� If there were no expressions to evaluate to a SQL true value,�� the value of any of the expressions to evaluate to a SQL NULL is�� returned. If there were no such expressions as well, #f is�� returned.�� In the absence of the expressions that evaluate to SQL NULL�� values, the semantics is the same as for `(or test-1 ...)'. (historical revision 5134)

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sql-null The sql-null extension implements the following interface. (sql-null) Return an object, corresponding to a SQL NULL value. The object is guaranteed to be of a type disjoint from all of the R5RS' standard types. It's unspecified whether the values returned by this function will be `eq?' to each other: (eq? (sql-null) (sql-null)) => unspecified. (sql-null? OBJECT) Return #t if OBJECT is a SQL NULL object. Return #f otherwise. (sql-not OBJECT) Return OBJECT if OBJECT is a SQL NULL object. Return the value of `(not OBJECT)' otherwise. (sql-not (sql-null)) => SQL NULL; (sql-not 'a) => #f; (sql-not #f) => #t; (let ((null (sql-null))) (eq? null (sql-not null))) => #t. Syntax: (sql-and TEST-1 ...) The TEST expressions are evaluated from left to right, and the value of the first expression that evaluates to a false value is returned, and any remaining TESTs are not evaluated. If there were no expressions to evaluate to a false value, the value of any of the expressions to evaluate to a SQL NULL is returned. If there were no such expressions as well, #t is returned. (sql-and 1) => 1; (sql-and #t (sql-null)) => SQL NULL; (sql-and #f (sql-null)) => #f. In the absence of the expressions that evaluate to SQL NULL values, the semantics is the same as for `(and test-1 ...)'. Syntax: (sql-or test-1 ...) The TEST expressions are evaluated from left to right, and the value of the first expression that evaluates to a value, other than SQL NULL and a false value (a ``SQL true'' value), is returned, and any remaining TESTs are not evaluated. If there were no expressions to evaluate to a SQL true value, the value of any of the expressions to evaluate to a SQL NULL is returned. If there were no such expressions as well, #f is returned. In the absence of the expressions that evaluate to SQL NULL values, the semantics is the same as for `(or test-1 ...)'.