Learn ADA-SPARK with Real Code Examples

with Ada.Text_IO;
procedure Hello is
begin
    Ada.Text_IO.Put_Line("Hello, World from SPARK Ada!");
end Hello;

A minimal SPARK Ada program that outputs 'Hello, World!'.

function Safe_Divide(X, Y : Integer) return Integer
    with Pre => Y /= 0,
    Post => Safe_Divide'Result * Y = X is
begin
    return X / Y;
end Safe_Divide;

A SPARK function that safely divides two numbers, using contracts to ensure correctness.

with Ada.Text_IO;
procedure Sum_Numbers is
    A, B, C : Integer;
begin
    A := 5;
    B := 7;
    C := A + B;
    Ada.Text_IO.Put_Line("Sum = " & Integer'Image(C));
end Sum_Numbers;

A SPARK Ada program adding two numbers and printing the result.

function Factorial(N : Natural) return Natural is
begin
    if N = 0 then
        return 1;
    else
        return N * Factorial(N - 1);
    end if;
end Factorial;

A recursive SPARK Ada function to compute factorial of a number.

function Is_Even(X : Integer) return Boolean is
begin
    return X mod 2 = 0;
end Is_Even;

A SPARK Ada function that returns True if a number is even.

function Array_Sum(Arr : array (Positive range <>) of Integer) return Integer is
    Sum : Integer := 0;
begin
    for I in Arr'Range loop
        Sum := Sum + Arr(I);
    end loop;
    return Sum;
end Array_Sum;

A SPARK Ada function that sums all elements of an integer array.

function Max(X, Y : Integer) return Integer is
begin
    if X >= Y then
        return X;
    else
        return Y;
    end if;
end Max;

A SPARK Ada function returning the maximum of two integers.

procedure Swap(A, B : in out Integer) is
    Temp : Integer;
begin
    Temp := A;
    A := B;
    B := Temp;
end Swap;

A SPARK Ada procedure that swaps the values of two integers using in-out parameters.

with Ada.Text_IO;
procedure Loop_Print is
begin
    for I in 1 .. 5 loop
        Ada.Text_IO.Put_Line(Integer'Image(I));
    end loop;
end Loop_Print;

A SPARK Ada program that prints numbers from 1 to 5 using a loop.

function Is_Prime(N : Natural) return Boolean is
begin
    if N <= 1 then
        return False;
    end if;
    for I in 2 .. N - 1 loop
        if N mod I = 0 then
        return False;
        end if;
    end loop;
    return True;
end Is_Prime;

A SPARK Ada function that checks if a number is prime.