(* Don't allow simpl to expand out these functions *)
Arguments natToWord : simpl never.
Arguments weq : simpl never.
(* Making wlt_dec opaque is necessary to prevent the [exact H] in the * example below from blowing up.. *)
Global Opaque wlt_dec.
Definition test_wlt_f (a : nat) (b : nat) : nat :=
if wlt_dec (natToWord 64 a) $0 then 0 else 0.

Lemma wordToNat_wplus': forall sz (a b: word sz),
(#a + #b < pow2 sz)%nat ->
#(a ^+ b) = #a + #b.