Enum type is used to check value to be one of enumerable

For example:

  iex> import Talos
  iex> genders = enum(members: ["male", "female"])
  iex> Talos.valid?(genders, "male")
  true
  iex> Talos.valid?(genders, "female")
  true
  iex> Talos.valid?(genders, "heli")
  false

Also there can be another Talos types:

  iex> digit_string = %Talos.Types.StringType{regexp: ~r/^\d+$/}
  iex> numbers = %Talos.Types.EnumType{members: [digit_string, %Talos.Types.IntegerType{}]}
  iex> Talos.valid?(numbers, "1")
  true
  iex> Talos.valid?(numbers, 1)
  true
  iex> Talos.valid?(numbers, "One")
  false

Additional parameters:

allow_nil - allows value to be nil

members - list of possible values or TalosTypes