mklbtz

// Here, I’ve added a function to Array called `partition`. 
// In short, the function will partition the Array into a Dictionary based on a function 
// which takes an Element of the Array and returns its corresponding Key into the Dictionary.

extension Array {
  func partition<Key>(key: (Element)->Key) -> [Key: [Element]] {
  var groups = [Key: [Element]]()
    for element in self {
      let key = key(element)
      var group = groups[key] ?? [Element]()

mklbtz

# The MIT License (MIT)
#
# Copyright (c) 2015 Michael Bates
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:

mklbtz

# O(nk)
class Array
  def unzip ary
    return [] if ary.empty?
    count = ary.first.count
    (0...count).map { |i| 
      ary.map { |tuple| 
        raise 'inconsistent tuple size' if tuple.count != count
        tuple[i] 
      }

mklbtz

require 'active_support'

module OptionSet
  extend ActiveSupport::Concern

  included do
    attr_reader :value
    include Comparable
    include Enumerable

mklbtz

module AutoRake
  require 'rake'
  Rails.application.load_tasks if Rake::Task.tasks.empty?

  def const_missing(const)
    mod = Module.new
    mod.extend AutoRake
    const_set(const, mod)
  end

mklbtz

# A method for opening the `source_location`
# of a method or proc in your preferred editor.
# Depends on the presence of $EDITOR in your environment.
module OpenSource
  def open_source
    return false unless
      loc = source_location and
      loc.first != '(irb)'
    path = loc.join(':') # append the line number to the file path.
    system("eval \"$EDITOR #{path}\"")

mklbtz

class Object
  # List Methods defined directly in the receiver's class.
  def my_methods
    methods_from(self.class)
  end

  # List Methods with names matching the regex.
  def methods_matching(regex)
    methods_where { |meth| regex.match(meth.name.to_s) }
  end

mklbtz

# A Numeric-like class that can represent algebraic expressions.
# Uses typecases to define what operations are representable.
class Algebra
  include Enum

  # Represents number literals
  typecase :scalar, value: Numeric do
    def to_s
      value.to_s
    end

mklbtz

// A Number-like type that can represent algebraic expressions.
public enum Algebra {
  case scalar(Double)
  case variable(name: String, () -> Double)
  indirect case add(Algebra, Algebra)
  indirect case subtract(Algebra, Algebra)
  indirect case multiply(Algebra, by: Algebra)
  indirect case divide(Algebra, by: Algebra)
  indirect case magnitude(Algebra)
  indirect case raise(Algebra, toPower: Int)

mklbtz

/// Useful as a type-safe String identifier for objects, records, etc.
/// Generic type A is the type of the object being "identified".
public struct Identifier<A>: Equatable, Hashable, Comparable {
  public let string: String

  public init(_ string: String) {
    self.string = string
  }

  public var hashValue: Int {