Section Env.
Variable d : nat.
Definition seq_of_rV (v : 'rV_d) : seq F := fgraph [ffun i => v 0 i].

(* Specifications: *)
Lemma size_seq_of_rV v : size (seq_of_rV v) = d.
Lemma eval_row_var e k : eval_mx (row_env e) (row_var k) = e`_k :> 'rV_d.
End Env.