CharType
	CharSpace
	CharWord
	CharPunctuation

inst Eq CharType
	eq (l, r)
		case (l, r)
			(CharSpace, CharSpace)
				return True
			(CharWord, CharWord)
				return True
			(CharPunctuation, CharPunctuation)
				return True
			_
				return False

fn char-type (c Char)
	if c is-alphanumeric() or c == '-' or c == '_'
		return CharWord
	elif c is-whitespace()
		return CharSpace
	else
		return CharPunctuation

fn is-word-boundary (l Char, r Char): char-type(l) /= char-type(r)


inst Str CharType
	chars (self _):
		(case self) chars()
			CharPunctuation: 'Punct'
			CharWord: 'Word'
			CharSpace: 'Space'
			_: todo()