Theorem: List.drop_all (GMLInit/Data/List/Basic.lean)

State before:
α : Type u_1
as : List α
⊢ drop as.length as = []
Tactic:
induction as with
| nil =>
  rw [drop_nil]
| cons a as ih =>
  rw [length_cons]
  rw [drop_succ_cons]
  rw [ih]
State after:
no goals

State before:
case nil
α : Type u_1
⊢ drop [].length [] = []
Tactic:
rw [drop_nil]
State after:
no goals

State before:
case cons
α : Type u_1
a : α
as : List α
ih : drop as.length as = []
⊢ drop (a :: as).length (a :: as) = []
Tactic:
rw [length_cons]
State after:
case cons
α : Type u_1
a : α
as : List α
ih : drop as.length as = []
⊢ drop as.length.succ (a :: as) = []

State before:
case cons
α : Type u_1
a : α
as : List α
ih : drop as.length as = []
⊢ drop as.length.succ (a :: as) = []
Tactic:
rw [drop_succ_cons]
State after:
case cons
α : Type u_1
a : α
as : List α
ih : drop as.length as = []
⊢ drop as.length as = []

State before:
case cons
α : Type u_1
a : α
as : List α
ih : drop as.length as = []
⊢ drop as.length as = []
Tactic:
rw [ih]
State after:
no goals