8.16.0.1
Roman Numerals
| (require roman-numeral) | package: roman-numeral |
This library provides utilities for parsing and writing Roman numerals.
procedure
(number->roman number [#:case output-case])
→ (and/c string? #rx"^(?i:[mdclxvi]+)$") number : exact-positive-integer?
output-case : (or/c 'lower 'upper) = (current-roman-numeral-case)
Returns the Roman numeral representation of number
as a string. The string will be in lower case if
output-case is 'lower
(the default) or in upper case otherwise.
Examples:
> (number->roman 1990) "mcmxc"
> (number->roman 1666) "mdclxvi"
> (parameterize ([current-roman-numeral-case 'upper]) (number->roman 1666)) "MDCLXVI"
Changed in version 0.1 of package roman-numeral: Added #:case argument.
parameter
(current-roman-numeral-case) → (or/c 'lower 'upper)
(current-roman-numeral-case output-case) → void? output-case : (or/c 'lower 'upper)
= 'lower
Specifies whether strings returned by number->roman
use upper case or lower case when no #:case
argument is given.
procedure
(roman->number numeral) → exact-positive-integer?
numeral : (and/c string? #rx"^(?i:[mdclxvi]+)$")
Returns the number represented by the Roman numeral string
numeral.
Roman numeral strings that do not use
the standard subtractive forms are supported, but numeral
must be a valid Roman numeral, not simply an arbitrary sequence
of the characters listed in the contract.
Examples:
> (roman->number "mcmiv") 1904
> (roman->number "mcMlIv") ; case is ignored 1954
; non-standard Roman numerals > (roman->number "iiii") 4
> (number->roman 4) "iv"
> (roman->number "xiix") 18
> (roman->number "iixx") 18
> (number->roman 18) "xviii"
> (roman->number "MDCDIII") 1903
> (number->roman 1903) "mcmiii"
> (roman->number "MDCCCCX") 1910
> (number->roman 1910) "mcmx"
> (eval:error (roman->number "cdm")) ; not a valid Roman numeral roman->number: malformed Roman numeral string
given: "cdm"