Goal:
  
  A : Type
  P : nat → A → Type
  n : nat
  l' : list A
  H : Alli P n ([] ++ l')
  ============================
   (Alli P n [] × Alli P (#|[]| + n) l')


DEBUG:Going to execute:
fun => <coq-core.plugins.ltac::split@0>

Goals:
  
  A : Type
  P : nat → A → Type
  n : nat
  l' : list A
  H : Alli P n ([] ++ l')
  ============================
   (Alli P n [])

  
  A : Type
  P : nat → A → Type
  n : nat
  l' : list A
  H : Alli P n ([] ++ l')
  ============================
   (Alli P (#|[]| + n) l')


DEBUG:Going to execute:
try constructor