Tagless-final as a pattern works also fine in OO languages. It's called "object algebras" there. https://oleksandrmanzyuk.wordpress.com/2014/06/18/from-object-

Tagless-final as a pattern works also fine in OO languages. It's called "object algebras" there. https://oleksandrmanzyuk.wordpress.com/2014/06/18/from-object-algebras-to-finally-tagless-interpreters-2/ https://oleksandrmanzyuk.wordpress.com/2014/06/18/from-objec... In general it's one of the most elegant solutions to the expression problem I've seen so far.