Goal:
  
  A : Type
  P : A → Prop
  Q : A → Prop
  p : A → bool
  Hp : ∀ x : A, Q x → reflect (P x) (p x)
  HP1 : list A
  HP : Forall P HP1
  ============================
   ([] = HP1
    → let H := CoreTactics.block in
      let H0 := CoreTactics.block in forallb p [] = true)


DEBUG:Going to execute:
cbv beta iota delta [TODO projection TODO projection] in id, id'
DEBUG LTAC Evaluated term: HP1
DEBUG LTAC Evaluated term: (list A)
Level 3: type of id
 has value 
(list A)