Theorem: dropColumn_spec1 (Table/Proofs.lean)

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
⊢ ∀ (t : Table sch) (c : η) (hc : Schema.HasName c sch), nrows (dropColumn t c) = nrows t
Tactic:
intros
State after:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t✝ : Table sch
c✝ : η
hc✝ : Schema.HasName c✝ sch
⊢ nrows (dropColumn t✝ c✝) = nrows t✝

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t✝ : Table sch
c✝ : η
hc✝ : Schema.HasName c✝ sch
⊢ nrows (dropColumn t✝ c✝) = nrows t✝
Tactic:
simp only [nrows, dropColumn, Schema.length_eq_List_length]
State after:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t✝ : Table sch
c✝ : η
hc✝ : Schema.HasName c✝ sch
⊢ List.length (List.map (Row.removeColumn hc✝) t✝.rows) = List.length t✝.rows

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t✝ : Table sch
c✝ : η
hc✝ : Schema.HasName c✝ sch
⊢ List.length (List.map (Row.removeColumn hc✝) t✝.rows) = List.length t✝.rows
Tactic:
apply List.length_map
State after:
no goals