Built-In Protocols
Elixir comes with the following protocols:
- Enumerable and Collectable
- Inspect
- List.Chars
- String.Chars
To play with these, we’ll implement a trivial datatype that represents the collection of 0s and 1s in an integer. The underlying representation is trivial:
| defmodule Bitmap do |
| defstruct value: 0 |
| |
| @doc """ |
| A simple accessor for the 2^bit value in an integer |
| |
| iex> b = %Bitmap{value: 5} |
| %Bitmap{value: 5} |
| iex> Bitmap.fetch_bit(b,2) |
| 1 |
| iex> Bitmap.fetch_bit(b,1) |
| 0 |
| iex> Bitmap.fetch_bit(b,0) |
| 1 |
| """ |
| def fetch_bit(%Bitmap{value: value}, bit) do |
| use Bitwise |
| |
| (value >>> bit) &&& 1 |
| end |
| end |
The fetch_bit function uses the >>> and &&& functions in ...
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