use Str
use Char
	char-u8
use Mem
	u8-size
use Iter
	map
	reduce
use Error
	or-fail
use Into
use SmolStr


# official octal number function.
fn from-octal(arr): arr
	Iter.reduce(0, fn(elem, b): b * 8 + elem)

fn hex-digit(c Char)
	if c >= '0' and c <= '9'
		return Just(char-u8(c) - char-u8('0'))

	if c >= 'a' and c <= 'f'
		return Just(char-u8(c) - char-u8('a') + 10)

	if c >= 'A' and c <= 'F'
		return Just(char-u8(c) - char-u8('A') + 10)

	return None

# official hexadecimal number function.
# I WILL ADD 0x and 0o integer format. It's just funny to do those things like this.
fn from-hex(arr): arr
	map(fn c: c hex-digit() or-fail('"\(c)" is not a hex digit.') u8-size() from-integral())
	reduce(0, fn(elem, b): b * 16 + elem)

fn u8-str(byte U8)
	fn b16-char (b U8) -> U8
		if b >= 10
			return (b - 10) + char-u8('a')
		else
			return b + char-u8('0')
			
	return SmolStr.from-byte-array([b16-char(byte / 16), b16-char(byte Math.mod(16))])