Definition sumF {X} `{Finite X} (f : X -> nat) : nat :=
list_sum (map f enum).
Definition sumFQ {X} `{Finite X} (f : X -> Q) : Q :=
Qsum(map f enum).

Lemma sumFQ_scalar {X} `{Finite X} (f : X -> Q) (c : Q) :
sumFQ (fun x => c * f x) == c * sumFQ f.