Contains functionality for list comphrensions in ExDiceRoller.

ExDiceRoller also has a certain amount of list comprehension support when calculating dice roll equations and ‘keeping’ rolls. The default behavior when working with kept rolls is as follows:

1. If one side of an expression is a list, and the other a value, the action will apply the value to each value in the list.
2. If both sides of an expression are lists of equal length, the values of each list are applied to their counterpart in the other list. An error is raised if the lengths of the two lists are different.
3. Combination rolls, such as 3d5d6, will perform each roll expressions in succession. Kept values from each roll expression is then used as the number of sides in the succeeding expression.

Example of one side of an expression being a kept list and the other a value:

iex> {:ok, fun} = ExDiceRoller.compile("5d6+11")
iex> fun.(opts: [:keep])
[14, 13, 17, 15, 16]

Example of both sides being lists:

iex> {:ok, fun} = ExDiceRoller.compile("5d6+(5d10+20)")
iex> fun.(opts: [:keep])
[25, 32, 34, 30, 26]

Example with lists of differing lengths:

iex> ExDiceRoller.roll("5d6+6d6", opts: [:keep])
** (ArgumentError) cannot use math operators on lists of differing lengths

Example of dice rolls of dice rolls:

iex> ExDiceRoller.roll("1d1d4", opts: [:keep])
[4]
iex> ExDiceRoller.roll("2d1d4", opts: [:keep])
[3, 2]
iex> ExDiceRoller.roll("2d6d4", opts: [:keep])
[2, 3, 2, 4, 4, 4, 3, 3]