mylist.exs

defmodule MyList do
  def len([]), do: 0
  def len([_head|tail]), do: 1 + len(tail)
  def square([]), do: []
  def square([ head | tail ]), do: [ head * head | square(tail)]

  def add_1([]), do: []
  def add_1([ head | tail ]), do: [head + 1 | add_1(tail)]

  def map([], _func), do: []
  def map([ head | tail ], func ), do: [func.(head) | map(tail, func)]

  def reduce([], value, _), do: value
  def reduce([ head | tail ], value, func) do
    reduce(tail, func.(head,value), func)
  end

  def mapsum([], _fun), do: 0
  def mapsum([head | tail ], fun) do
    fun.(head) + mapsum(tail, fun)

  
  end

  def max([n]), do: n
  def max([head|tail]), do: Kernel.max(head,max(tail))

  def caesar([], _n),  do: [] 
  def caesar([head |tail], n) when head+n <= ?z, do: [head+n| caesar(tail,n)]
  def caesar([head|tail], n), do: [head+n-26| caesar(tail, n)]

end