Commit 3a262d02 authored by Johannes Kloos's avatar Johannes Kloos
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Proofs of infinity and Fresh instances.

We prove that various types are infinite, notably:
- nat, N, positive and Z;
- string (using pretty-printing of nat);
- option, with an infinite element type;
- list, with an inhabited element type.

Furthermore, we instantiate Fresh for strings.
parent a8d02255
......@@ -39,4 +39,5 @@ theories/list.v
(* Copyright (c) 2012-2017, Coq-std++ developers. *)
(* This file is distributed under the terms of the BSD license. *)
From stdpp Require Import pretty fin_collections.
Instance string_infinite: Infinite string := {| inject := λ x, "~" +:+ pretty x |}.
Instance nat_infinite: Infinite nat := {| inject := id |}.
Instance N_infinite: Infinite N := {| inject_injective := Nat2N.inj |}.
Instance pos_infinite: Infinite positive := {| inject_injective := SuccNat2Pos.inj |}.
Instance Z_infinite: Infinite Z := {| inject_injective := Nat2Z.inj |}.
Instance option_infinite `{Infinite A}: Infinite (option A) := {| inject := Some inject |}.
Program Instance list_infinite `{Inhabited A}: Infinite (list A) :=
{| inject := λ i, replicate i inhabitant |}.
Next Obligation.
intros * i j eqrep%(f_equal length).
rewrite !replicate_length in eqrep; done.
(** Derive fresh instances. *)
Section StringFresh.
Context `{FinCollection string C, (x: string) (s: C), Decision (x s)}.
Global Instance string_fresh: Fresh string C := fresh_generic.
Global Instance string_fresh_spec: FreshSpec string C := _.
End StringFresh.
\ No newline at end of file
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