> The wrapper/adapter hell that comes out of the Expression Problem

Yeah, I got lucky in my work (see sibling comment https://news.ycombinator.com/item?id=45207880).

For me, it was PageObjects all the way down, which "just composed".

Something like this:

  (defprotocol IPageObject
    "Each PageObject MUST implement the IPageObject protocol."
    (page-object [this])
    (exists? [this])
    (visible? [this]))

And then an implementation like this:

  (defrecord Checkbox [target-css]
    IPageObject
    (page-object [this]
      this)
    (exists? [this]
      ;; webdriver check if target-css exists
      )
    (visible? [this]
      ;; webdriver check if target-css is visible
      )

    Selectable
    (select [this]
      ;; webdriver select the target
      )

    (deselect [this]
      ;; webdriver undo selection
      )
  
    (selected? [this]
      ;; webdriver return true if target selected
      )  

    Value
    (get-value [this]
      ;; webdriver return current selection state
      (selected? this)))

Thanks to Records (stateless, type-identified, hash-map semantics), the PageObject model composes arbitrarily. i.e. A Page is itself a PageObject containing a tree of arbitrarily nested PageObjects... i.e. PageObjects all the way down.

Solid gold!

(edit: x-link to sibling comment)