#SCALA Lab1 COMPLETE

Функция fib: (Int, Int => Boolean) => List[Int], порождающая
последовательность чисел Фибоначчи, не превышающих заданного целого числа и
удовлетворяющих некоторому предикату.



//
// original idea by Dasha.S
//

val fib_helper: (Int, Int => Boolean, Int, Int) => List[Int] = {
case (n, p, p1, p2) if (n < p2)     => List()
case (n, p, p1, p2) if (p(p2))      => p2::fib_helper(n, p, p2, p1 + p2)
case (n, p, p1, p2)                 => fib_helper(n, p, p2, p1 + p2)
}

val fib: (Int, Int => Boolean) => List[Int] = {
(n, p) => fib_helper (n, p, 0, 1)
}




val fib: (Int) => List[Int] = {
case (0)        => List(1)
case (1)        => 1 :: fib(0)
case (x)        => (fib(x-1)(0) + fib(x-2)(0)) :: fib(x-1)
}

val sort_top: (List[Int], Int) => List[Int] = {
case (Nil, a)                   => List()
case (x :: xs, a) if (x < a)    => x :: sort_top(xs, a)
case (x :: xs, a)               => sort_top(xs, a)
}

val sort_pred: (List[Int], Int => Boolean) => List[Int] = {
case (Nil, a)                   => List()
case (x :: xs, p) if (p(x))     => x :: sort_pred(xs, p)
case (x :: xs, p)               => sort_pred(xs, p)
}

val main: (Int, Int => Boolean) => List[Int] = {
(n, p) => sort_pred(sort_top(fib(n), n), p)
}


//fib(10, _ > 3):
//(8, 5)