[joshka]

I, a Datapoint of 1, find the functional style to generally express the ideas of what's happening to be significantly easier to grok. Particularly if intermediate variables and conversion constructors are introduced rather than relying on full chains. E.g.:

    function processUsers(users: User[]): FormattedUser[] {
      let adults = users.filter(user => user.age >= 18);
      return adults.map(user => FormattedUser.new_adult(user));
    }

On the performance tip, what scale are we talking? Is it relevant to the target system? Obviously the example is synthetic, so we can't know that, but does it seem like this would have a runtime performance that is meaningful in some sort of reasonable use case?