PAL语言

// Sample PAL program.
let Abs x = // compute absolute value of argument
        x < 0.0 -> -x ! x
in
let Sqrt x = // compute square root of x
        f(x/2.0) // initial approximation is x/2
    where rec f t = // a recursive function for Newton's method
        Abs(t*t - x) < 0.005 // is t close enough?
        -> t // Yes, so return t as result.
        !  f(0.5*(t + x/t)) // No, so keep trying...
in
let i = 0 // a counter, to have its square root taken.
in
L:​  // the main loop of this rather simple little program..
    Write (i, '*t', Sqrt(ItoR i), '*n');
    i​ := i + 1;
    i < 11 // did we just do 10?
    ->     // not yet, so keep going
        go​to L
    !      // All done, so say so and go home.
    Write '*nAll done.*n'