rtoal

if #arg ~= 1 then
  io.stderr:write('Exactly one argument required\n')
  os.exit(1)
end

function generatePermutations(n, a)
  if n == 0 then
    print(utf8.char(table.unpack(a)))
  else
    for i = 1, n do

rtoal

function powerpowermod(a, b, c, p)
  if !isprime(p)
    error("Go away. I not gonna even try this.")
  end
  return powermod(a, powermod(b, c, p-1), p)
end

rtoal

Vector = (function (class, meta, prototype)
  class.new = function (i, j)
    return setmetatable({i = i, j = j}, meta)
  end
  prototype.magnitude = function (self)
    return math.sqrt(self.i * self.i + self.j * self.j)
  end
  meta.__index = prototype
  meta.__add = function (self, v)
      return class.new(self.i + v.i, self.j + v.j)

rtoal

arg = {'x': 0}

def f(param):
    same_ids = id(arg) == id(param)
    different_ids = not same_ids
    param = {'y': 4}
    arg_changed = 'y' in arg
    print('Call by value: {}'.format(different_ids))
    print('Call by sharing: {}'.format(same_ids and not arg_changed))
    print('Call by reference: {}'.format(same_ids and arg_changed))

rtoal

# Runtimes for various complexity functions, sort of.
#
# A hacked-together little Python3 script printing runtimes for various
# complexity functions to standard output.
#
# The script isn't very general or customizable; you have to edit the
# source code to explore different functions or use different values
# of n.

import math

rtoal

# 10-7-4 Water Jug Problem

# Get 2 units of water in the 7-container or the 4-container

# Starting state is (0,7,4)
# Operations are F10, F7, F4, T107, T104, T710, T74, T410, T47
# Goal states are (x,2,z) and (x,y,2)

operations = {
    'F10'  : lambda x, y, z: [10, y, z],

rtoal

An API Design Choice

Let's say we have an API endpoint

POST /customers

which creates a customer given a suitable JSON document and returns a 201 CREATED on success.

rtoal

class Pager {

    private int offset;
    private int limit;

    private Pager() {}

    public static Pager withOffset(int offset) {return new Pager().offset(offset);}
    public Pager offset(int offset) {this.offset = offset; return this;}
    public int offset() {return this.offset;}

rtoal

# Makes an enum class with instances (class attributes) having uppercase 
# names while the string representations can be in any case. For example, 
# Color = enum_class('Color', 'red', 'amber', 'green') returns class Color
# with members Color.RED, Color.AMBER, and Color.GREEN. The __str__ instance 
# methods produce 'red', 'green', and 'blue', respectively. To get the 
# instance from the string, use, for example, Color.from_string('blue'), 
# which will return Color.BLUE.

def enum_class(classname, *values):
    cls = type(classname, (), {})

rtoal

# Makes an enum class whose instances are all constants with uppercase names,
# but whose case of string representations are customizable. For example,
# Color = make_enum_class('red', 'amber', 'green') returns the class Color
# with members Color::RED, Color::AMBER, and Color::GREEN. The to_s methods
# produce 'red', 'green', and 'blue', respectively. To get the instance
# from the string, use, for example, Color.from_string('blue'), which will
# return Color.BLUE.

def make_enum_class(*constants)
  cap = ->(s){s.upcase.gsub(/ /, '_')}