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Extend err_if_nil #1

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Extend err_if_nil #1

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11 changes: 10 additions & 1 deletion lib/oxide.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -184,17 +184,26 @@ defmodule Oxide.Result do
@doc ~S"""
Convert a maybe-nil value to a result.

Maps `nil` to `{:error, reason}` and any non-`nil` value to `{:ok, value}`.
Maps `nil` and `{:ok, nil}` to `{:error, reason}`, passes errors through and otherwise maps `value`, or {:ok, value}` to `{:ok, value}`.

iex> %{"key" => "value"} |> Map.get("key") |> Result.err_if_nil(:notfound)
{:ok, "value"}
iex> %{"key" => "value"} |> Map.get("missing") |> Result.err_if_nil(:notfound)
{:error, :notfound}
iex> {:ok, nil} |> Result.err_if_nil(:notfound)
{:error, :notfound}
iex> {:ok, "value"} |> Result.err_if_nil(:notfound)
{:ok, "value"}
iex> {:error, :badthing} |> Result.err_if_nil(:notfound)
{:error, :badthing}

"""
@spec err_if_nil(any(), any()) :: t()
def err_if_nil(value, reason)
def err_if_nil(value, reason) when is_nil(value), do: {:error, reason}
def err_if_nil({:ok, value}, reason) when is_nil(value), do: {:error, reason}
def err_if_nil({:ok, value}, _reason) when not is_nil(value), do: {:ok, value}
def err_if_nil({:error, reason}, _reason), do: {:error, reason}
def err_if_nil(value, _reason) when not is_nil(value), do: {:ok, value}

@doc ~S"""
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