vericert.common.Show

Class Show A : Type :=
  {
  show : A -> string
  }.

Instance showBool : Show bool :=
  {
  show := fun b:bool => if b then "true" else "false"
  }.

Fixpoint string_of_nat_aux (time n : nat) (acc : string) : string :=
  let d := match n mod 10 with
           | 0 => "0" | 1 => "1" | 2 => "2" | 3 => "3" | 4 => "4" | 5 => "5"
           | 6 => "6" | 7 => "7" | 8 => "8" | _ => "9"
           end in
  let acc' := d ++ acc in
  match time with
  | 0 => acc'
  | S time' =>
    match n / 10 with
    | 0 => acc'
    | n' => string_of_nat_aux time' n' acc'
    end
  end.

Definition string_of_nat (n : nat) : string :=
  string_of_nat_aux n n "".

Instance showNat : Show nat :=
  {
  show := string_of_nat
  }.

Instance showZ : Show Z :=
  {
  show a := show (Z.to_nat a)
  }.

Instance showPositive : Show positive :=
  {
  show a := show (Zpos a)
  }.