This procedure returns the product of its arguments.

This procedure returns the product of its arguments.

This procedure returns the sum of its arguments.

This procedure returns the sum of its arguments.

With two or more arguments, this procedure returns the difference of its arguments, associating to the left. With one argument, however, it returns the additive inverse of its argument.

(
->char-set
[
string?
x
]
)
⟹
char-set?
(
->char-set
[
char?
x
]
)
⟹
char-set?
(
->char-set
[
char-set?
x
]
)
⟹
char-set?

Coerces x into a char-set. X may be a string, character or char-set. A string is converted to the set of its constituent characters; a character is converted to a singleton set; a char-set is returned as-is. This procedure is intended for use by other procedures that want to provide "user-friendly", wide-spectrum interfaces to their clients.

With two or more arguments, this procedure returns the quotient of its arguments, associating to the left. With one argument, however, it returns multiplicative inverse of its argument. It is an error if any argument of / other than the first is an exact zero. If the first argument is an exact zero, an implementation may return an exact zero unless one of the other arguments is a NaN.

With two or more arguments, this procedure returns the quotient of its arguments, associating to the left. With one argument, however, it returns the multiplicative inverse of its argument.

This procedure returns #t if its arguments are monotonically increasing, and #f otherwise. If any of the arguments are +nan.0, predicate returns #f. It does not distinguish between inexact zero and inexact negative zero. The predicate is transitive. Note: While it is not an error to compare inexact numbers using this predicate, the results are unreliable because a small inaccuracy can affect the result. When in doubt, consult a numerical analyst.

This procedure returns #t if its arguments are monotonically increasing.

This procedure returns #t if its arguments are monotonically non-decreasing.

This procedure returns #t if its arguments are monotonically non-decreasing, and #f otherwise. If any of the arguments are +nan.0, predicate returns #f. It does not distinguish between inexact zero and inexact negative zero. The predicate is transitive. Note: While it is not an error to compare inexact numbers using this predicate, the results are unreliable because a small inaccuracy can affect the result. When in doubt, consult a numerical analyst.

(
<=?
[
comparator?
comparator
]
object1
object2
object3
...
)
⟹
boolean?

=?, <?, >?, <=?, >=? These procedures are analogous to the number, character, and string comparison predicates of Scheme. They allow the convenient use of comparators to handle variable data types.
These procedures apply the equality and ordering predicates of comparator to the objects as follows. If the specified relation returns #t for all objecti and objectj where n is the number of objects and 1 <= i < j <= n, then the procedures return #t, but otherwise #f. Because the relations are transitive, it suffices to compare each object with its successor. The order in which the values are compared is unspecified.

(
<?
[
comparator?
comparator
]
object1
object2
object3
...
)
⟹
boolean?

This procedure returns #t if its arguments are equal.

This procedure returns #t if its arguments are equal, and #f otherwise. If any of the arguments are +nan.0, the predicate return #f. It does not distinguish between inexact zero and inexact negative zero. This predicate is transitive. Note: While it is not an error to compare inexact numbers using this predicate, the results are unreliable because a small inaccuracy can affect the result; this is especially true of =. When in doubt, consult a numerical analyst.

(
=?
[
comparator?
comparator
]
object1
object2
object3
...
)
⟹
boolean?

This procedure returns #t if its arguments are monotonically decreasing.

This procedure returns #t if its arguments are monotonically decreasing, and #f otherwise. If any of the arguments are +nan.0, predicate returns #f. It does not distinguish between inexact zero and inexact negative zero. The predicate is transitive. Note: While it is not an error to compare inexact numbers using this predicate, the results are unreliable because a small inaccuracy can affect the result. When in doubt, consult a numerical analyst.

This procedure returns #t if its arguments are monotonically non-increasing.

This procedure returns #t if its arguments are monotonically non-increasing, and #f otherwise. If any of the arguments are +nan.0, predicate returns #f. It does not distinguish between inexact zero and inexact negative zero. The predicate is transitive. Note: While it is not an error to compare inexact numbers using this predicate, the results are unreliable because a small inaccuracy can affect the result. When in doubt, consult a numerical analyst.

(
>=?
[
comparator?
comparator
]
object1
object2
object3
...
)
⟹
boolean?

(
>?
[
comparator?
comparator
]
object1
object2
object3
...
)
⟹
boolean?

Abs returns the absolute value of its argument.

The abs procedure returns the absolute value of its argument.

(
alist->hash-table
[
list?
alist
]
[
comparator?
comparator
]
arg
...
)
⟹
hash-table?

(
alist->hash-table
[
list?
alist
]
[
comparator?
comparator
]
arg
...
)
⟹
hash-table?
(
alist->hash-table
[
list?
alist
]
[
procedure?
equality-predicate
]
arg
...
)
⟹
hash-table?
(
alist->hash-table
[
list?
alist
]
[
procedure?
equality-predicate
]
[
procedure?
hash-function
]
arg
...
)
⟹
hash-table?

equality-predicate
⟹
(
λ
a
b
)
⟹
boolean?

hash-function
⟹
(
λ
obj
)
⟹
integer?

Returns a newly allocated hash-table as if by make-hash-table using comparator and the args. It is then initialized from the associations of alist. Associations earlier in the list take precedence over those that come later. The second form is for compatibility with SRFI 69, and is deprecated.

(
alist-cons
key
datum
[
list?
alist
]
)
⟹
list?

(lambda (key datum alist) (cons (cons key datum) alist)) Cons a new alist entry mapping key -> datum onto alist.

(
alist-copy
[
list?
alist
]
)
⟹
list?

Make a fresh copy of alist. This means copying each pair that forms an association as well as the spine of the list.

(
alist-delete
key
[
list?
alist
]
)
⟹
list?
(
alist-delete
key
[
list?
alist
]
[
procedure?
=
]
)
⟹
list?

=
⟹
(
λ
a
b
)
⟹
*

alist-delete, alist-delete! alist-delete deletes all associations from alist with the given key, using key-comparison procedure =, which defaults to equal?. The dynamic order in which the various applications of = are made is not specified. Return values may share common tails with the alist argument. The alist is not disordered -- elements that appear in the result alist occur in the same order as they occur in the argument alist. The comparison procedure is used to compare the element keys ki of alist's entries to the key parameter in this way: (= key ki). Thus, one can reliably remove all entries of alist whose key is greater than five with (alist-delete 5 alist <). alist-delete! is the linear-update variant of alist-delete. It is allowed, but not required, to alter cons cells from the alist parameter to construct the result.

(
alist-delete!
key
[
list?
alist
]
)
⟹
list?
(
alist-delete!
key
[
list?
alist
]
[
procedure?
=
]
)
⟹
list?

=
⟹
(
λ
a
b
)
⟹
*

alist-delete, alist-delete! alist-delete deletes all associations from alist with the given key, using key-comparison procedure =, which defaults to equal?. The dynamic order in which the various applications of = are made is not specified. Return values may share common tails with the alist argument. The alist is not disordered -- elements that appear in the result alist occur in the same order as they occur in the argument alist. The comparison procedure is used to compare the element keys ki of alist's entries to the key parameter in this way: (= key ki). Thus, one can reliably remove all entries of alist whose key is greater than five with (alist-delete 5 alist <). alist-delete! is the linear-update variant of alist-delete. It is allowed, but not required, to alter cons cells from the alist parameter to construct the result.

(
and
⟨
test1
⟩
...
)

The 〈test〉 expressions are evaluated from left to right, and the value of the first expression that evaluates to a false value (see section 6.3.1) is returned. Any remaining ex- pressions are not evaluated. If all the expressions evaluate to true values, the value of the last expression is returned. If there are no expressions then #t is returned.

(
and
⟨
test1
⟩
...
)

Semantics: The test expressions are evaluated from left to right, and if any expression evaluates to #f (see section 6.3), then #f is returned. Any remaining expressions are not evaluated. If all the expressions evaluate to true values, the values of the last expression are returned. If there are no expressions, then #t is returned.

(
and-let*
(
⟨
claw
⟩
...
)
⟨
body
⟩
)

⟨claw⟩:=

(
⟨
variable
⟩
⟨
expression
⟩
)
(
⟨
expression
⟩
)
⟨
bound-variable
⟩

(
any
[
procedure?
pred
]
[
list?
clist1
]
[
list?
clist2
]
...
)
⟹
*

pred
⟹
(
λ
obj1
obj2
...
)
⟹
*

Applies the predicate across the lists, returning true if the predicate returns true on any application. If there are n list arguments clist1 ... clistn, then pred must be a procedure taking n arguments and returning a single value, interpreted as a boolean (that is, #f means false, and any other value means true). any applies pred to the first elements of the clisti parameters. If this application returns a true value, any immediately returns that value. Otherwise, it iterates, applying pred to the second elements of the clisti parameters, then the third, and so forth. The iteration stops when a true value is produced or one of the lists runs out of values; in the latter case, any returns #f. The application of pred to the last element of the lists is a tail call. Note the difference between find and any -- find returns the element that satisfied the predicate; any returns the true value that the predicate produced. Like every, any's name does not end with a question mark -- this is to indicate that it does not return a simple boolean (#t or #f), but a general value.