Ltac wlt_ind :=
match goal with
| [ |- forall (n: word ?len), ?P ] =>
refine (well_founded_ind (@wlt_wf len) (fun n => P) _)
end.

Lemma natToWord_discriminate: forall sz, (sz > 0)%nat -> natToWord sz 0 <> natToWord sz 1.
Definition bit_dec : forall (a : word 1), {a = $0} + {a = $1}.