samjowen

defmodule TodoListTest do
  use ExUnit.Case
  doctest TodoList

  test "it can convert a cleaned csv line into a todo entry" do
    assert TodoList.convert_csv_line_to_entry("2018/12/19,Dentist") == %{
             date: ~D[2018-12-19],
             title: "Dentist"
           }
  end

samjowen

defmodule TodoList do
  defstruct auto_id: 1, entries: %{}

  def new(entries \\ []) do
    Enum.reduce(entries, %TodoList{}, fn entry, todo_acc ->
      add_entry(todo_acc, entry)
    end)
  end

  def add_entry(todo_list, entry) do

samjowen

defmodule Fraction do
  defstruct a: nil, b: nil

  def new(a, b) do
    %Fraction{a: a, b: b}
  end

  def value(%Fraction{a: a, b: b}) do
    a / b
  end

samjowen

defmodule RangeGenerator do
  @spec range(pos_integer(), pos_integer()) :: list(pos_integer())
  def range(minimum, maximum)
      when is_integer(minimum) and minimum > -1 and
             is_integer(maximum) and maximum > minimum do
    make_range([], minimum, maximum)
  end

  defp make_range(current_list, minimum, maximum, iteration) do
    case iteration < minimum do

samjowen

# Remember that the end of a list is not nil, like a singly linked list like you might see in other languages.
# In Elixir, the list is always of pattern [head | tail], not something like [head | nil].
# What you might think could be [head | nil] is actaully like this: [head | []] i.e., an empty list.

defmodule ListHelper do
  def list_len(list) do
    get_len(0, list)
  end

  defp get_len(current_len, []) do

samjowen

# Tail calls are actually very efficient in Elixir as they don't involve stack pushes, 
# they are closer to a GO TO in something like FORTRAN.

defmodule TimeTeller do
  @moduledoc """
  A simple way to create a clock in the console that updates every second.
  """

  def clock(:first) do
    IO.puts(NaiveDateTime.utc_now())

samjowen

defmodule NaturalNums do
  # Base case: if n is 1, print 1
  def print(1) do
    IO.puts(1)
  end

  # Recursive case: if n is a positive integer greater than 1, print numbers from 1 to n
  # The guard clause "when n > 1 and is_integer(n)" ensures that this function is only called for positive integers greater than 1
  def print(n) when n > 1 and is_integer(n) do
    print(n - 1)