Chain

Section

import IEx.Helpers

Section

defmodule Chain do
  def new() do
    {}
  end

  def add(chain, item) do
    {item, chain}
  end

  def head({first, _rest}) do
    first
  end

  def tail({_first, rest}) do
    rest
  end

  def show({}) do
    ""
  end

  def show({head, rest}) do
    inspect(head) <> "-" <> show(rest)
  end

  def total({head, rest}) do
    head + total(rest)
  end

  def total({}) do
    0
  end

  def count({_head, rest}) do
    1 + count(rest)
  end

  def count({}) do
    0
  end

  def reduce({}, acc, _reducer) do
    acc
  end

  def reduce({head, rest}, acc, reducer) do
    new_accumulator = reducer.(head, acc)
    reduce(rest, new_accumulator, reducer)
  end
end

Chain.new()
|> Chain.add(3)
|> Chain.add(2)
|> Chain.add(1)
|> Chain.count()

Chain.new()
|> Chain.show()

Chain.new()
|> Chain.add(3)
|> Chain.add(2)
|> Chain.add(1)
|> Chain.reduce(0, fn i, acc -> i + acc end)