4.3.4 Fixnums

package: base

The racket/fixnum library provides operations like fx+ that consume and produce only fixnums. The operations in this library are meant to be safe versions of unsafe operations like unsafe-fx+. These safe operations are generally no faster than using generic primitives like +.

The expected use of the racket/fixnum library is for code where the require of racket/fixnum is replaced with

(require (filtered-in
          (λ (name)
            (and (regexp-match #rx"^unsafe-fx" name)
                 (regexp-replace #rx"unsafe-" name "")))
          racket/unsafe/ops))

to drop in unsafe versions of the library. Alternately, when encountering crashes with code that uses unsafe fixnum operations, use the racket/fixnum library to help debug the problems.

4.3.4.1 Fixnum Arithmetic

procedure
(fx+ a ...) → fixnum?
  a : fixnum?
procedure
(fx- a b ...) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fx* a ...) → fixnum?
  a : fixnum?
procedure
(fxquotient a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fxremainder a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fxmodulo a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fxabs a) → fixnum?
  a : fixnum?

Safe versions of unsafe-fx+, unsafe-fx-, unsafe-fx*, unsafe-fxquotient, unsafe-fxremainder, unsafe-fxmodulo, and unsafe-fxabs. The exn:fail:contract:non-fixnum-result exception is raised if the arithmetic result would not be a fixnum.

Changed in version 7.0.0.13 of package base: Allow zero or more arguments for fx+ and fx* and one or more arguments for fx-.

procedure
(fxand a ...) → fixnum?
  a : fixnum?
procedure
(fxior a ...) → fixnum?
  a : fixnum?
procedure
(fxxor a ...) → fixnum?
  a : fixnum?
procedure
(fxnot a) → fixnum?
  a : fixnum?
procedure
(fxlshift a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fxrshift a b) → fixnum?
  a : fixnum?
  b : fixnum?

Safe versions of unsafe-fxand, unsafe-fxior, unsafe-fxxor, unsafe-fxnot, unsafe-fxlshift, and unsafe-fxrshift. The exn:fail:contract:non-fixnum-result exception is raised if the arithmetic result would not be a fixnum.

Changed in version 7.0.0.13 of package base: Allow any number of arguments for fxand, fxior, and fxxor.

procedure
(fx= a b ...) → boolean?
  a : fixnum?
  b : fixnum?
procedure
(fx< a b ...) → boolean?
  a : fixnum?
  b : fixnum?
procedure
(fx> a b ...) → boolean?
  a : fixnum?
  b : fixnum?
procedure
(fx<= a b ...) → boolean?
  a : fixnum?
  b : fixnum?
procedure
(fx>= a b ...) → boolean?
  a : fixnum?
  b : fixnum?
procedure
(fxmin a b ...) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fxmax a b ...) → fixnum?
  a : fixnum?
  b : fixnum?

Safe versions of unsafe-fx=, unsafe-fx<, unsafe-fx>, unsafe-fx<=, unsafe-fx>=, unsafe-fxmin, and unsafe-fxmax.

Changed in version 7.0.0.13 of package base: Allow one argument, in addition to allowing two or more.

procedure
(fx->fl a) → flonum?
a : fixnum?
procedure
(fl->fx fl) → fixnum?
fl : flonum?

Conversion between fixnums and flonums with truncation in the case of converting a flonum to a fixnum.

The fx->fl function is the same as exact->inexact or ->fl constrained to a fixnum argument.

The fl->fx function is the same as truncate followed by inexact->exact or fl->exact-integer constrained to returning a fixnum. If the truncated flonum does not fit into a fixnum, the exn:fail:contract exception is raised.

Changed in version 7.7.0.8 of package base: Changed fl->fx to truncate.

procedure
(fixnum-for-every-system? v) → boolean?
v : any/c

Returns #t if v is a fixnum and is represented by fixnum by every Racket implementation, #f otherwise.

Added in version 7.3.0.11 of package base.

4.3.4.2 Fixnum Vectors

A fxvector is like a vector, but it holds only fixnums. The only advantage of a fxvector over a vector is that a shared version can be created with functions like shared-fxvector.

Two fxvectors are equal? if they have the same length, and if the values in corresponding slots of the fxvectors are equal?.

A printed fxvector starts with #fx(, optionally with a number between the #fx and (. See Reading Vectors for information on reading fxvectors and Printing Vectors for information on printing fxvectors.

procedure
(fxvector? v) → boolean?
v : any/c

Returns #t if v is a fxvector, #f otherwise.

procedure
(fxvector x ...) → fxvector?
x : fixnum?

Creates a fxvector containing the given fixnums.

Example:

> (fxvector 2 3 4 5)
(fxvector 2 3 4 5)

procedure
(make-fxvector size [x]) → fxvector?
size : exact-nonnegative-integer?
x : fixnum? = 0

Creates a fxvector with size elements, where every slot in the fxvector is filled with x.

Example:

> (make-fxvector 4 3)
(fxvector 3 3 3 3)

procedure
(fxvector-length vec) → exact-nonnegative-integer?
vec : fxvector?

Returns the length of vec (i.e., the number of slots in the fxvector).

procedure
(fxvector-ref vec pos) → fixnum?
vec : fxvector?
pos : exact-nonnegative-integer?

Returns the fixnum in slot pos of vec. The first slot is position 0, and the last slot is one less than (fxvector-length vec).

procedure
(fxvector-set! vec pos x) → fixnum?
  vec : fxvector?
  pos : exact-nonnegative-integer?
  x : fixnum?

Sets the fixnum in slot pos of vec. The first slot is position 0, and the last slot is one less than (fxvector-length vec).

procedure
(fxvector-copy vec [start end]) → fxvector?
  vec : fxvector?
  start : exact-nonnegative-integer? = 0
  end : exact-nonnegative-integer? = (vector-length v)

Creates a fresh fxvector of size (- end start), with all of the elements of vec from start (inclusive) to end (exclusive).

procedure
(in-fxvector vec [start stop step]) → sequence?
  vec : fxvector?
  start : exact-nonnegative-integer? = 0
  stop : (or/c exact-integer? #f) = #f
  step : (and/c exact-integer? (not/c zero?)) = 1

Returns a sequence equivalent to vec when no optional arguments are supplied.

The optional arguments start, stop, and step are as in in-vector.

An in-fxvector application can provide better performance for fxvector iteration when it appears directly in a for clause.

syntax
(for/fxvector maybe-length (for-clause ...) body ...)
syntax
(for*/fxvector maybe-length (for-clause ...) body ...)

maybe-length =
| #:length length-expr
| #:length length-expr #:fill fill-expr

length-expr : exact-nonnegative-integer?
fill-expr : fixnum?

Like for/vector or for*/vector, but for fxvectors. The default fill-expr produces 0.

procedure
(shared-fxvector x ...) → fxvector?
x : fixnum?

Creates a fxvector containing the given fixnums. For communication among places, the new fxvector is allocated in the shared memory space.

Example:

> (shared-fxvector 2 3 4 5)
(fxvector 2 3 4 5)

procedure
(make-shared-fxvector size [x]) → fxvector?
size : exact-nonnegative-integer?
x : fixnum? = 0

Creates a fxvector with size elements, where every slot in the fxvector is filled with x. For communication among places, the new fxvector is allocated in the shared memory space.

Example:

> (make-shared-fxvector 4 3)
(fxvector 3 3 3 3)

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2	Notation for Documentation
3	Syntactic Forms
4	Datatypes
5	Structures
6	Classes and Objects
7	Units
8	Contracts
9	Pattern Matching
10	Control Flow
11	Concurrency and Parallelism
12	Macros
13	Input and Output
14	Reflection and Security
15	Operating System
16	Memory Management
17	Unsafe Operations
18	Running Racket
	Bibliography
	Index

4.1	Equality
4.2	Booleans
4.3	Numbers
4.4	Strings
4.5	Byte Strings
4.6	Characters
4.7	Symbols
4.8	Regular Expressions
4.9	Keywords
4.10	Pairs and Lists
4.11	Mutable Pairs and Lists
4.12	Vectors
4.13	Boxes
4.14	Hash Tables
4.15	Sequences and Streams
4.16	Dictionaries
4.17	Sets
4.18	Procedures
4.19	Void
4.20	Undefined

4.3.1	Number Types
4.3.2	Generic Numerics
4.3.3	Flonums
4.3.4	Fixnums
4.3.5	Extflonums