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( circular-list? obj ) boolean?
True if x is a circular list. A circular list is a value such that for every n >= 0, cdrn(x) is a pair. Terminology: The opposite of circular is finite.
( circular-list? obj ) boolean?
True if x is a circular list. A circular list is a value such that for every n >= 0, cdrn(x) is a pair. Terminology: The opposite of circular is finite.
( complex? obj ) boolean?
number?, complex?, real?, rational?, integer? These numerical type predicates can be applied to any kind of argument, including non-numbers. They return #t if the object is of the named type, and otherwise they return #f. In general, if a type predicate is true of a number then all higher type predicates are also true of that number. Consequently, if a type predicate is false of a number, then all lower type predicates are also false of that number. If z is a complex number, then (real? z) is true if and only if (zero? (imag-part z)) is true. If x is an inexact real number, then (integer? x) is true if and only if (= x (round x)). The numbers +inf.0, -inf.0, and +nan.0 are real but not rational. Note: The behavior of these type predicates on inexact numbers is unreliable, since any inaccuracy might affect the result. Note: In many implementations the complex? procedure will be the same as number?, but unusual implementations may represent some irrational numbers exactly or may extend the number system to support some kind of non-complex numbers.
( dotted-list? obj ) boolean?
True if x is a finite, non-nil-terminated list. That is, there exists an n >= 0 such that cdrn(x) is neither a pair nor (). This includes non-pair, non-() values (e.g. symbols, numbers), which are considered to be dotted lists of length 0.
( dotted-list? obj ) boolean?
True if x is a finite, non-nil-terminated list. That is, there exists an n >= 0 such that cdrn(x) is neither a pair nor (). This includes non-pair, non-() values (e.g. symbols, numbers), which are considered to be dotted lists of length 0.
( error-object? obj ) boolean?
Returns #t if obj is an object created by error or one of an implementation-defined set of objects. Otherwise, it returns #f. The objects used to signal errors, including those which satisfy the predicates file-error? and read-error?, may or may not satisfy error-object?.
( file-error? obj ) boolean?
read-error?, file-error? Error type predicates. Returns #t if obj is an object raised by the read procedure or by the inability to open an input or output port on a file, respectively. Otherwise, it returns #f.
( list? obj ) boolean?
Returns #t if obj is a list. Otherwise, it returns #f. By definition, all lists have finite length and are terminated by the empty list.
( not-pair? obj ) boolean?
(lambda (x) (not (pair? x))). Provided as a procedure as it can be useful as the termination condition for list-processing procedures that wish to handle all finite lists, both proper and dotted.