Allows you to use arithmetical operations on any type that implements the proper protocols.

For each arithmetical operation, a different protocol is used so that types for which only a subset of these operations makes sense can still work with those.

Basic Usage

Usually, Numbers is used in another module by using alias Numbers, as: N, followed by calling the functions using this aliased but still descriptive syntax: total_price = N.mult(N.add(price, fee), vat)

Because Numbers dispatches based on protocol definitions, you only need to swap what kind of arguments are used to change the type of the result.

Overloaded Operators

As explicit opt-in functionality, Numbers will add overloaded operators to your module, if you write use Numbers, overload_operators: true

This will alter a + b, a - b, a * b, a / b, -a and abs(a) to dispatch to the corresponding functions in the Numbers module.

Do note that these overloaded operator versions are not allowed in guard tests, which is why this functionality is only provided as an opt-in option to use when an algorithm would be too unreadable without it.

Examples:

Using built-in numbers:

iex> alias Numbers, as: N
iex> N.add(1, 2)
3
iex> N.mult(3,5)
15
iex> N.mult(1.5, 100)
150.0

Using Decimals: (requires the Decimal library.)

iex> alias Numbers, as: N
iex> d = Decimal.new(2)
iex> N.div(d, 10)
#Decimal<0.2>
iex> small_number = N.div(d, 1234)
#Decimal<0.001620745542949756888168557536>
iex> N.pow(small_number, 100)
#Decimal<9.364478495445313580679473524E-280>

Defining your own Numbers implementations

See Numbers.Protocols for a full explanation on how to do this.