with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;

procedure Constants is
    
    -- Declares a constant value.
    S : constant String := "constant";
    
    procedure Print_String (S : in String) is
    begin
        Put_Line(S);
    end Print_String;
    
begin
    Print_String(S);

    -- A const declaration can appear anywhere a var declaration can.
    N : constant Integer := 500000000;

    -- Constant expressions perform arithmetic with arbitrary precision.
    D : constant Long_Float := 3.0E20 / Long_Float(N);
    Put(D, Exp => 0); New_Line;
    
    -- A numeric constant has no type until it’s given one, such as by an explicit conversion.
    Put(Integer(D)); New_Line;

    -- A number can be given a type by using it in a context that requires one, such as a variable assignment or function call.
    -- For example, here "Ada.Float_IO.Sin" expects a Float.
    Put_Line(Float'Image(Ada.Numerics.Elementary_Functions.Sin(Float(N))));
    
end Constants;