3.2.4 Fixnums

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) (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.

3.2.4.1 Fixnum Arithmetic

procedure
(fx+ a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fx- a b) → fixnum?
  a : fixnum?
  b : fixnum?
procedure
(fx* a b) → fixnum?
  a : fixnum?
  b : 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.

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

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.

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

Safe versions of unsafe-fx->fl and unsafe-fl->fx.

3.2.4.2 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?.

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>

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>

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 (for-clause ...) body ...)
(for/fxvector #:length length-expr (for-clause ...) body ...)
syntax
(for*/fxvector (for-clause ...) body ...)
(for*/fxvector #:length length-expr (for-clause ...) body ...)

Like for/vector or for*/vector, but for fxvectors.

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>

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>

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

3.1	Booleans and Equality
3.2	Numbers
3.3	Strings
3.4	Byte Strings
3.5	Characters
3.6	Symbols
3.7	Regular Expressions
3.8	Keywords
3.9	Pairs and Lists
3.10	Mutable Pairs and Lists
3.11	Vectors
3.12	Boxes
3.13	Hash Tables
3.14	Sequences and Streams
3.15	Dictionaries
3.16	Sets
3.17	Procedures
3.18	Void and Undefined

3.2.1	Number Types
3.2.2	Generic Numerics
3.2.3	Flonums
3.2.4	Fixnums