Commit aa051883 authored by Robbert's avatar Robbert

Merge branch 'ralf/empty' into 'master'

more instances for the empty type

See merge request !90
parents 1ae85171 af4cedfa
Pipeline #19350 passed with stage
in 10 minutes and 8 seconds
......@@ -102,6 +102,11 @@ Section inj_countable'.
Next Obligation. intros x. by f_equal/=. Qed.
End inj_countable'.
(** ** Empty *)
Program Instance Empty_set_countable : Countable Empty_set :=
{| encode u := 1; decode p := None |}.
Next Obligation. by intros []. Qed.
(** ** Unit *)
Program Instance unit_countable : Countable unit :=
{| encode u := 1; decode p := Some () |}.
......
......@@ -184,6 +184,8 @@ Instance bool_eq_dec : EqDecision bool.
Proof. solve_decision. Defined.
Instance unit_eq_dec : EqDecision unit.
Proof. solve_decision. Defined.
Instance Empty_set_eq_dec : EqDecision Empty_set.
Proof. solve_decision. Defined.
Instance prod_eq_dec `{EqDecision A, EqDecision B} : EqDecision (A * B).
Proof. solve_decision. Defined.
Instance sum_eq_dec `{EqDecision A, EqDecision B} : EqDecision (A + B).
......
......@@ -246,6 +246,12 @@ Qed.
Lemma option_cardinality `{Finite A} : card (option A) = S (card A).
Proof. unfold card. simpl. by rewrite fmap_length. Qed.
Program Instance Empty_set_finite : Finite Empty_set := {| enum := [] |}.
Next Obligation. by apply NoDup_nil. Qed.
Next Obligation. intros []. Qed.
Lemma Empty_set_card : card Empty_set = 0.
Proof. done. Qed.
Program Instance unit_finite : Finite () := {| enum := [tt] |}.
Next Obligation. apply NoDup_singleton. Qed.
Next Obligation. intros []. by apply elem_of_list_singleton. Qed.
......
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