`:erlang.float` vs `value * 1.0`: Which is the prefered way?

I’d start by asking what reason you have to convert an integer to a float. Then I’d look at how performant this needs to be (hot path or not) and then I’d wonder if it’s worth comparing performance between a bif/nif float/1 vs doing a random calculation like x/1 or x*1.0. I’d guess all of them are fast, but no matter what, one will be the fastest. From a readability standpoint float/1 will convey the cleanest that all you do there is convert integer to float.

Thanks for your answer. For instance, we have a Ash calculation which defines type: :float and we get values as float as strings and integers. Therefore we need to convert int to float. Im not really worried about performance as this is not hot path but more what the community uses so our code is in line with best practices.

Hi, if you plan to do arithmetic with this float better option is to use Decimal, as Decimal handles precision for those operations.

Decimal.new(42)

Okay, since there doesn’t seem too much opinion on this, is maybe my setup flawed since i would expect that people do this regularly?

I have a Ash calculation which has :float as return type:
calculate :dossier_center_coordinates_x, :float, {SomeCalcThatNeedsToReturnFloat, axis: :x}
and in that Calculation i have these functions to match the return type.

defp to_float(value) when is_float(value), do: value

defp to_float(value) when is_integer(value), do: value / 1

defp to_float(value) when is_binary(value) do
  case Float.parse(value) do
    {float, _rest} -> float
    :error -> nil
  end
end

defp to_float(_value), do: nil

Should this be done differently since people don’t seem to have this use case? In my case the calculation should return :float but since its a Module Calculation i don’t think this is enforced anywhere outside of the module.

Ash uses ecto under the hood so you can simply reuse ectos casting logic:

case Ecto.Type.cast(:float, value) do
  {:ok, float} -> float
  _ -> nil
end

Ash also seems to wrap this in Ash.Type.cast_input/3.