[_diyu]

I've always had better luck restricting FP to using things like map, reduce, filter, (etc) inside methods as an implementation detail, but having the structure of the app use OOP.

[pjmlp]

Incidently that is how FP in done in Smalltalk as well.

All those methods, and reactive patterns (Observer and such) were already present in Smalltalk-80.

[mercer]

Elixir, I suppose, would be a 'modern' example too.

[scruple]

This is where I've landed when writing Ruby code, as well, and it's served me really well.