The expression problem has been known for quite some time [0].
Final tagless[1] is an fp approach and Object algebras[2] is an oop approach to solving this problem.
Setting aside the timelime, reading the various claims it seems like Eric Meijer, Anders Hejlsberg et al still had a hard time obfuscating the math to make patentable claims.
A naive read (on my part) of the claims looks like they wished to patent Object Algebras.
Final tagless[1] is an fp approach and Object algebras[2] is an oop approach to solving this problem.
Setting aside the timelime, reading the various claims it seems like Eric Meijer, Anders Hejlsberg et al still had a hard time obfuscating the math to make patentable claims. A naive read (on my part) of the claims looks like they wished to patent Object Algebras.
[0] https://homepages.inf.ed.ac.uk/wadler/papers/expression/expr...
[1] https://okmij.org/ftp/tagless-final/
[2] https://blog.acolyer.org/2015/11/13/scrap-your-boilerplate-w...