with ada.text_io; use ada.text_io; 
with ada.integer_text_io; use ada.integer_text_io; 
procedure basic_recs  is 
    -- Declare a record type with two FIELDS
    -- Its fields do not have default values
    type P1 is record
        x: Natural;
        y: Natural;
    end record;

    -- For this type, the fields do have default values
    type P2 is record
        x: Natural := 1;
        y: Natural := 2;
    end record;

    -- Declaration allocates record with specified name
    a1: P1;           -- Fields have unknown values
    a2: P2;           -- Fields have default values

    -- Explicit initialization.  
    -- Overrides any default values.
    b1: P1 := (3, 4);  -- (3, 4) is an aggregate value
    b2: P2 := (y => 6, others => 5);  -- Keywords.  

begin
    put(b1.x);    -- 3
    put(b2.y);    -- 6

    put(a1.x);    -- Unknown value printed
    a1.x := 7;    -- Assign one field
    put(a1.x);    -- 7

    -- Assign with aggregate value
    a1 := (8, 9);  
    a2 := (x => 8, y => 9);  -- Keyword aggregate
    put(a1.x);    -- 8
    b1 := (others => 10);  -- Others works too
    put(b1.x);    -- 10

    -- Element by element assignment and comparison
    if a1 = b1 then put("EQ"); else put("NE"); end if;
    a1 := b1;
    if a1 = b1 then put("EQ"); else put("NE"); end if;

    -- Type names must match for := and =. 
    -- a1 := a2;  -- Compile error
    -- if a1 = a2 then put("EQ"); else put("NE"); end if;

    -- Value semantics.  Compare with Java.
    a1.x := 99;
    if a1 = b1 then put("EQ"); else put("NE"); end if;
    put(b1.x);

end basic_recs;