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|
From Coq Require Import
Strings.String
Bool.Bool
Arith.Arith.
Local Open Scope string.
Module 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
}.
End Show.
Export Show.
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