rsslldnphy

require 'rspec'

class Object

  def peg(&block)
    block.call(self)
  end

  def wend(arg)
    Wender.new(self, arg)

rsslldnphy

(defun restart-sml ()
  (sml-prog-proc-switch-to)
  (end-of-buffer)
  (comint-delchar-or-maybe-eof 0))

(defun run-sml-tests-now ()
  (let* ((code-file-name
           (replace-regexp-in-string "_tests" "" (buffer-file-name)))
	 (test-file-name
	   (replace-regexp-in-string "\.sml" "_tests.sml" code-file-name)))

rsslldnphy

"Nils - what are your Options?" - Russell Dunphy

Tony Hoare, inventor of the null reference, calls it his "billion dollar mistake".
Although Ruby goes some way to correcting it by making `nil` at least be a class
with some reasonably helpful stuff on it, you'll no doubt have been hit by a
`NoMethodError: undefined method 'foo'` just as many times as me.

So, given this problem exists, I want to convince you of a few things.

First, that there are not one, but two types of `nil`.

rsslldnphy

## Model code

class Customer < ActiveRecord::Base

  def find_by_name(name)
    Option[where(name: name).first]
  end
end

## Controller code

rsslldnphy

-module(infinite).
-compile(export_all).

%%% Usage
%
%   Ints = infinite:stream(0, fun (X) -> X + 1 end).
%
%   % Numbers from 0 to 9
%   infinite:take(Ints, 10).
%

rsslldnphy

class DCode

  def initialize(assessment, user)
    @assessment = assessment
    @user       = user
  end

  def code
    "#{site.name[0,2]}-#{department_code}".upcase
  end

rsslldnphy

normal score:      41 (4 then 1)
spare:             3/
strike:            X
score then gutter: 4-


34X--3/34

rsslldnphy

## Making Option[[]], Option[{}] and Option[""] return None

Looked at a certain way, it does make a kind of sense. I can see how you got the idea.
A None is itself a kind of empty collection, so why wouldn't an Option of an empty collection also be a None?

However, I think there are some important things we need to consider.

The first one is - why would you be creating an optional collection - what value would you be getting from doing so?
And what value would you be getting from empty collections being interpreted as None?

rsslldnphy

module Main where

import System.Environment

main :: IO ()
main = do
  args <- getArgs
  mapM_ putStrLn $ sort args

sort :: (Ord a) => [a] -> [a]

rsslldnphy

module Main where

import System.Environment

main :: IO ()
main = do
  args <- getArgs
  mapM_ putStrLn $ sort args

sort :: (Ord a) => [a] -> [a]