Keles, A. (2023, July 13). Learner’s Guide to Functional Programming#0: Sum Types, Booleans and Naturals in Javascript. Alperen Keles. https://alperenkeles.com/posts/learners-guide-to-functional-programming0-sum-types-booleans-and-naturals-in-javascript/. Archived at https://web.archive.org/web/https://alperenkeles.com/posts/learners-guide-to-functional-programming0-sum-types-booleans-and-naturals-in-javascript/