Goal:
    A : Type  n : nat  H : n < #|[]|
  ============================
   A


DEBUG:Going to execute:
try typeclasses eauto  10 with program
Level 0: Backtrace:

No head constant to reduce.
Level 0: Backtrace:

No head constant to reduce.
Level 0: Backtrace:

No head constant to reduce.
Level 0: Backtrace:

No head constant to reduce.
Level 0: Backtrace:

No head constant to reduce.
Level 0: Backtrace:

No applicable tactic.