No explicit provision of law.
Patent Examination Guidelines: Part III, Chapter 1, Rule 4.1.8
4.1.8 Computer programming language or computer program
A Computer program is a mere list of orders to have a computer operated.
Therefore, a computer program is not considered as a statutory invention. However, in the case of an invention where data processing with a computer program is specifically executed using a hardware, a data processing unit (machine) operating in association with the computer program, its operating method, and a computer readable medium carrying the computer program, the invention is viewed as a statutory invention.