I have been extensively working with dates recently and found the need to
create a function between?/3. This function takes first_date, second_date,
and target_date as inputs and returns a boolean indicating whether
target_date is between first_date and second_date, inclusive of the
boundaries if specified.
While the Timex library offers this functionality, the recently added
Calendar module in Elixir already provides most of the features I need,
except for this specific function. I believe it would be beneficial to
include this functionality in the Calendar module.
Proposal
*Function:* Calendar.between?/3
*Description:* This function checks if target_date falls between first_date
and second_date. By default, the boundaries are exclusive. An optional
keyword list allows the inclusion of boundaries.
*Example Usage:*
```elixir
Calendar.between?(date_1, date_2, date_3)
```
Returns true if date_3 is between date_1 and date_2, exclusive of date_1
and date_2.
```elixir
Calendar.between?(date_1, date_2, date_3, inclusive: true)
```
Returns true if date_3 is between date_1 and date_2, inclusive of date_1
and date_2.
Implementation
Here is a possible implementation of the between?/3 function:
```elixir
defmodule Calendar do
@moduledoc """
Provides functionality for working with dates and times.
"""
@doc """
Returns true if `target_date` is between `first_date` and `second_date`.
## Examples
iex> Calendar.between?(~D[2024-06-01], ~D[2024-06-30], ~D[2024-06-15])
true
iex> Calendar.between?(~D[2024-06-01], ~D[2024-06-30], ~D[2024-06-01])
false
iex> Calendar.between?(~D[2024-06-01], ~D[2024-06-30],
~D[2024-06-01], inclusive: true)
true
"""
@spec between?(Date.t(), Date.t(), Date.t(), Keyword.t()) :: boolean()
def between?(first_date, second_date, target_date, opts \\ []) do
inclusive = Keyword.get(opts, :inclusive, false)
if Date.compare(first_date, second_date) == :gt do
between?(second_date, first_date, target_date, opts)
else
case inclusive do
true ->
Date.compare(target_date, first_date) != :lt and
Date.compare(target_date, second_date) != :gt
false ->
Date.compare(target_date, first_date) == :gt and
Date.compare(target_date, second_date) == :lt
end
end
end
end
```
This addition would enhance the Calendar module's functionality by
providing a straightforward way to determine if a date falls within a
specified range.
Best regards
Edwin
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