Most programming languages interpret sequences of digits as base-10 numbers. Python adds syntax for the common alternate bases of binary, octal, and hexadecimal, which can be written with the prefixes `0b`

, `0o`

, and `0x`

, respectively (as in `0b10010`

= 18, `0o16`

= 14, and `0xff`

= 255). Clojure, however, is the only language I know that offers a built-in literal syntax for any base between 2 and 36.

To do so, it provides what is essentially an infix operator, `r`

. The digits to the left of the `r`

define the base (or radix), and the digits to the right define the number itself. For example, the binary, octal, and hexadecimal numbers given above can be expressed like this:

`2r10010`

`18`

`8r16`

`14`

`16rff`

`255`

Uppercase `R`

also works:

`2R10010`

`18`

For bases above 10, Clojure interprets letters as digits greater than nine, as is common with hexadecimal numbers, but it extends the scheme beyond F = 15:

`17rG`

`16`

That behavior reveals why radix literals only work up to base-36: the Latin alphabet only has 26 letters.

`36rZ`

`35`

In practice, I don't recall ever using any base other than binary, octal, or hexadecimal, but if you have, let me know.