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A lightweight solution for handling and storing money.
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As a general rule, using floats to store money is a bad idea.

Enter Monetized. A library that aims to facilitate the handling of money through a safe way to store currency values and and providing abstractions to perform arithmetical operations on those values.

Monetized leverages Decimal's ability to safely handle arbitrary precision to perform calculations on money values.

A typical %Monetized.Money{} struct will contain a value in the shape of a Decimal struct and a currency (if any) as a string.

Requires elixir version 1.3.x or above as per ecto 2.x


Monetized also ships with a Ecto.Type that gives us an easier way to store money.

alias Monetized.Money

schema "transaction" do
  field :description, :string
  field :balance, Money, default:


By doing this we're able to pass a %Money{} struct to the changeset and insert in the Repo since Ecto knows how to convert that struct into a primitive type to save and back when you read from it.

balance = Money.make("£ 100.50")
changeset = Transaction.changeset(%Transaction{}, %{description: "Invoice payment", balance: balance})

# Or

balance = %{value: "100.50", currency: "GBP"}
changeset = Transaction.changeset(%Transaction{}, %{description: "Invoice payment", balance: balance})

Check the docs for more.

Other usage

alias Monetized.Money
alias Monetized.Math

# Create with a string
iex> item_one = Money.make("£ 200.50")

# Or a float
iex> item_two = Money.make(10.25, [currency: "GBP"])

# Adding two moneys together
iex> Math.add(item_one, item_two)

# Or an integer
iex> balance = Money.make(100_000, [currency: "USD"])

# Substracting from money (currency inferred from balance)
iex> result = Math.sub(balance, 50_000)

# Getting the string representation
iex> Money.to_string(result, [currency_symbol: true])
"$ 50,000.00"

# You can also use `from_integer/2`, `from_float/2`, `from_decimal/2` and `from_string/2`
# respectively if the desired behavior is to raise when the amount is 
# not of the expected type.

# If either the symbol or the currency key is found within the string,
# that currency will be used. However, if a different currency is given in the
# options, it will take precedence.

iex> Money.from_string("£ 200")

iex> Money.from_string("200 EUR")

iex> Money.from_integer(200)

iex> Money.from_float(200.50)

iex> decimal =
...> Money.from_decimal(decimal, currency: "EUR")

iex> Money.from_integer("10")
** (FunctionClauseError) no function clause matching in Monetized.Money.from_integer/2
    (monetized) lib/money.ex:204: Monetized.Money.from_integer("10", [])

Check the docs for more examples


config :monetized, config: [
  delimiter: ",",
  separator: ".",
  currency: "USD",
  format: "%cs %n%s%d"


Add monetized to your list of dependencies in mix.exs:

def deps do
  [{:monetized, "~> 0.5.0"}]


  • New currencies can be added through the package's config
  • 1.0.0 ! yay!


$ mix deps.get
$ MIX_ENV=bench mix compile
$ MIX_ENV=bench mix bench


See for details.



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