# `Bylaw.Credo.Check.Elixir.FloatUsage`
[🔗](https://github.com/ryanzidago/bylaw/blob/v0.1.0-alpha.1/lib/bylaw/credo/check/elixir/float_usage.ex#L1)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

This check has a base priority of `high` and works with any version of Elixir.

## Explanation

Prefer `Decimal` over floats in Ecto migrations, Ecto schemas, and Elixir code.

Floats are approximate binary numbers. Many decimal values cannot be represented
exactly as floats, which can make calculations, rounding, equality checks, and
persisted values surprising for money, tax, rates, balances, quantities, and
other business data.

For example, a float calculation may keep a tiny representation error:

      0.1 + 0.2

Use the `Decimal` library and Ecto's `:decimal` type when a value needs decimal
precision or predictable rounding:

      Decimal.add(Decimal.new("0.1"), Decimal.new("0.2"))

Floats may still be appropriate for approximate measurements, statistics,
scientific calculations, graphics, telemetry, or other domains where small
precision differences are expected and acceptable.

## Examples

Avoid:

      add :amount, :float
      field :amount, :float
      Float.round(value, 2)
      amount = 1.25
      @spec amount() :: float()
Prefer:

      add :amount, :decimal
      field :amount, :decimal
      Decimal.round(value, 2)
      amount = Decimal.new("1.25")
      @spec amount() :: Decimal.t()

If a float is genuinely required, document the exception and disable the check locally.

## Notes

This check uses static AST analysis, so it favors clear source-level patterns over runtime behavior.

## Options

This check has no check-specific options. Configure it with an empty option list.

## Usage

Add this check to Credo's `checks:` list in `.credo.exs`:

```elixir
%{
  configs: [
    %{
      name: "default",
      checks: [
        {Bylaw.Credo.Check.Elixir.FloatUsage, []}
      ]
    }
  ]
}
```

## Check-Specific Parameters

*There are no specific parameters for this check.*

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

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*Consult [api-reference.md](api-reference.md) for complete listing*