Type-class implicits are not eager enough

[gebner]

When a function has a final type-class argument, then F* will apply it (and solve it via type-class search), but Pulse will not:
 

module TCArg
open Pulse
#lang-pulse

class droppable (p: slprop) = {
  drop_: stt unit p (fun _ -> emp)
}

let drop (p: slprop) {| droppable p |} = drop_ #p

instance droppable_emp : droppable emp = { drop_ = return_stt_noeq _ _ }

let foo_in_fstar = drop emp // works

fn foo_in_pulse () requires emp ensures emp {
(*
Expected type unit
  but drop emp
  has type {| _: droppable emp |} -> stt unit emp (fun _ -> emp)
*)
  drop emp; // doesn't work
}