3 Module locale/format

8.16.0.4

3 Module locale/format🔗ℹ

This module provides functions to format numbers, currency, and date/time values. The formats are locale-specific and retrieved from Module locale/language-info.

3.1 Numbers and Currency🔗ℹ

procedure
(format-number value) → string?
value : number?

Format a plain numeric value according to locale-specific conventions. In general this implies ensuring the correct decimal point and thousands separator characters as well as thousands grouping.

Examples:

> (require locale
           locale/format)
> (set-locale (make-locale-string "en"
                                  "US"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-number 1234567.89)
"1234567.89"

procedure
(format-currency value [internationl]) → string?
value : number?
internationl : boolean? = #f

Formatting a currency follows many of the conventions of format-number but also has to handle placement of currency symbols and sign symbols (see struct locale? for more details).

Examples:

> (require locale
           locale/format)
> (set-locale (make-locale-string "zh"
                                  "CN"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-currency 1234.89)
format-currency: broke its own contract
  promised: string?
  produced: #<void>
  in: the range of
      (->* (number?) (boolean?) string?)
  contract from:
      <pkgs>/racket-locale/locale/format.rkt
  blaming: <pkgs>/racket-locale/locale/format.rkt
   (assuming the contract is correct)
  at: <pkgs>/racket-locale/locale/format.rkt:19:3
> (set-locale (make-locale-string "ko"
                                  "KR"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-currency 1234.89)
format-currency: broke its own contract
  promised: string?
  produced: #<void>
  in: the range of
      (->* (number?) (boolean?) string?)
  contract from:
      <pkgs>/racket-locale/locale/format.rkt
  blaming: <pkgs>/racket-locale/locale/format.rkt
   (assuming the contract is correct)
  at: <pkgs>/racket-locale/locale/format.rkt:19:3
> (set-locale (make-locale-string "es"
                                  "ES"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-currency 1234.89)
format-currency: broke its own contract
  promised: string?
  produced: #<void>
  in: the range of
      (->* (number?) (boolean?) string?)
  contract from:
      <pkgs>/racket-locale/locale/format.rkt
  blaming: <pkgs>/racket-locale/locale/format.rkt
   (assuming the contract is correct)
  at: <pkgs>/racket-locale/locale/format.rkt:19:3

The international argument denotes whether the formatting should follow international standared conventions, and whether the local currency symbol should be replaced by a standard three letter currency identifier.

Examples:

> (require locale
           locale/format)
> (set-locale (make-locale-string "zh"
                                  "CN"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-currency 1234.89 #t)
format-currency: broke its own contract
  promised: string?
  produced: #<void>
  in: the range of
      (->* (number?) (boolean?) string?)
  contract from:
      <pkgs>/racket-locale/locale/format.rkt
  blaming: <pkgs>/racket-locale/locale/format.rkt
   (assuming the contract is correct)
  at: <pkgs>/racket-locale/locale/format.rkt:19:3

3.2 Dates and Times🔗ℹ

procedure
(format-date value) → string?
value : (or/c date? number?)

Formatting a date value comprises the ordering of the date components, any separator characters and any localized string elements.

Examples:

> (require locale
           locale/format
           racket/date)
> (define now (current-date))
> (set-locale (make-locale-string "en"
                                  "US"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-date now)
"4/3/25"
> (set-locale (make-locale-string "zh"
                                  "CN"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-date now)
"4/3/25"

procedure
(format-time value [am-pm]) → string?
value : (or/c date? number?)
am-pm : boolean? = #f

Formatting a time value comprises the ordering of the time components, any separator characters and any localized string elements.

Examples:

> (require locale
           locale/format
           racket/date)
> (define now (current-date))
> (set-locale (make-locale-string "en"
                                  "US"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-time now)
"0:38:47"
> (set-locale (make-locale-string "zh"
                                  "CN"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-time now)
"0:38:47"

procedure
(format-datetime value) → string?
value : (or/c date? number?)

Formatting a date-and-time value comprises the ordering of the various components, any separator characters and any localized string elements.

Examples:

> (require locale
           locale/format
           racket/date)
> (define now (current-date))
> (set-locale (make-locale-string "en"
                                  "US"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-datetime now)
"Thu May  3 0:38:47 2025"
> (set-locale (make-locale-string "zh"
                                  "CN"
                                  #:code-page (normalize-code-page 'utf-8)))
#f
> (format-datetime now)
"Thu May  3 0:38:47 2025"

1	Module locale
2	Module locale/ language-info
3	Module locale/ format
4	License