Trabb─Pardo─Knuth algorithm in Swift 2.0

tpk.swift

/**
http://rosettacode.org/wiki/Trabb_Pardo–Knuth_algorithm

The TPK algorithm is an early example of programming chrestomathy. 
It was used in Donald Knuth and Luis Trabb Pardo's Stanford tech report 
The Early Development of Programming Languages. 
The report traces the early history of work in developing computer languages in the 
1940s and 1950s, giving several translations of the algorithm.

The task is to implement the algorithm:
1. Use the function f(x) = | x | 0.5 + 5x3
2. The overflow condition is an answer of greater than 400.
3. The 'user alert' should not stop processing of other items of the sequence.
4. Print a prompt before accepting eleven, textual, numeric inputs.
5. You may optionally print the item as well as its associated result, but the results must be in reverse order of input.
6. The sequence S may be 'implied' and so not shown explicitly.
7. Print and show the program in action from a typical run here. 
(If the output is graphical rather than text then either add a screendump or describe textually what is displayed).

*/

import Foundation

print("Enter 11 numbers for the Trabb─Pardo─Knuth algorithm:")

let f: (Double) -> Double = { sqrt(fabs($0)) + 5 * pow($0, 3) }

(1...11)
    .generate()
    .map { i -> Double in
        print("\(i): ", terminator: "")
        guard let s = readLine(), let n = Double(s) else { return 0 }
        return n
    }
    .reverse()
    .forEach {
        let result = f($0)
        print("f(\($0))", result > 400.0 ? "OVERFLOW" : result, separator: "\t")
    }