# Is this string in a valid numeric format compatible with `to_f`?
	#
	# ~~~
	# assert "123".is_numeric  == true
	# assert "1.2".is_numeric  == true
	# assert "-1.2".is_numeric == true
	# assert "-1.23e-2".is_numeric == true
	# assert "1..2".is_numeric == false
	# assert "".is_numeric     == false
	# ~~~
	fun is_numeric: Bool
	do
		var has_point = false
		var e_index = -1
		for i in [0..length[ do
			var c = chars[i]
			if not c.is_numeric then
				if c == '.' and not has_point then
					has_point = true
				else if c == 'e' and e_index == -1 and i > 0 and i < length - 1 and chars[i-1] != '-' then
					e_index = i
				else if c == '-' and i == e_index + 1 and i < length - 1 then
				else
					return false
				end
			end
		end
		return not is_empty
	end