Fix dialyzer warning

lib/rdf/serialization/encoder.ex

@@ -4,7 +4,7 @@ defmodule RDF.Serialization.Encoder do
   `RDF.Serialization` format.
   """
 
-  alias RDF.{Dataset, Graph}
+  alias RDF.{Dataset, Graph, Description}
 
   @doc """
   Encodes a `RDF.Graph` or `RDF.Dataset`.
@@ -12,7 +12,8 @@ defmodule RDF.Serialization.Encoder do
   It returns an `{:ok, string}` tuple, with `string` being the serialized
   `RDF.Graph` or `RDF.Dataset`, or `{:error, reason}` if an error occurs.
   """
-  @callback encode(Graph.t() | Dataset.t(), keyword | map) :: {:ok, String.t()} | {:error, any}
+  @callback encode(Description.t() | Graph.t() | Dataset.t(), keyword | map) ::
+              {:ok, String.t()} | {:error, any}
 
   @doc """
   Encodes a `RDF.Graph` or `RDF.Dataset`.
@@ -22,7 +23,7 @@ defmodule RDF.Serialization.Encoder do
   Note: The `__using__` macro automatically provides an overridable default
   implementation based on the non-bang `encode` function.
   """
-  @callback encode!(Graph.t() | Dataset.t(), keyword | map) :: String.t()
+  @callback encode!(Description.t() | Graph.t() | Dataset.t(), keyword | map) :: String.t()
 
   defmacro __using__(_) do
     quote bind_quoted: [], unquote: true do
@@ -30,7 +31,7 @@ defmodule RDF.Serialization.Encoder do
 
       @impl unquote(__MODULE__)
       @dialyzer {:nowarn_function, encode!: 2}
-      @spec encode!(Graph.t() | Dataset.t(), keyword) :: String.t()
+      @spec encode!(Description.t() | Graph.t() | Dataset.t(), keyword) :: String.t()
       def encode!(data, opts \\ []) do
         case encode(data, opts) do
           {:ok, data} -> data

lib/rdf/serialization/format.ex

@@ -28,7 +28,7 @@ defmodule RDF.Serialization.Format do
   `decoder/0` functions in your `RDF.Serialization.Format` module.
   """
 
-  alias RDF.{Dataset, Graph}
+  alias RDF.{Dataset, Graph, Description}
 
   @doc """
   An IRI of the serialization format.
@@ -99,19 +99,21 @@ defmodule RDF.Serialization.Format do
       def read_file!(file, opts \\ []),
         do: RDF.Serialization.Reader.read_file!(decoder(), file, opts)
 
-      @spec write_string(Graph.t() | Dataset.t(), keyword) :: {:ok, String.t()} | {:error, any}
+      @spec write_string(Description.t() | Graph.t() | Dataset.t(), keyword) ::
+              {:ok, String.t()} | {:error, any}
       def write_string(data, opts \\ []),
         do: RDF.Serialization.Writer.write_string(encoder(), data, opts)
 
-      @spec write_string!(Graph.t() | Dataset.t(), keyword) :: String.t()
+      @spec write_string!(Description.t() | Graph.t() | Dataset.t(), keyword) :: String.t()
       def write_string!(data, opts \\ []),
         do: RDF.Serialization.Writer.write_string!(encoder(), data, opts)
 
-      @spec write_file(Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok | {:error, any}
+      @spec write_file(Description.t() | Graph.t() | Dataset.t(), Path.t(), keyword) ::
+              :ok | {:error, any}
       def write_file(data, path, opts \\ []),
         do: RDF.Serialization.Writer.write_file(encoder(), data, path, opts)
 
-      @spec write_file!(Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok
+      @spec write_file!(Description.t() | Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok
       def write_file!(data, path, opts \\ []),
         do: RDF.Serialization.Writer.write_file!(encoder(), data, path, opts)
 

lib/rdf/serialization/writer.ex

@@ -7,7 +7,7 @@ defmodule RDF.Serialization.Writer do
   use the proper `RDF.Serialization.Encoder` module.
   """
 
-  alias RDF.{Dataset, Graph}
+  alias RDF.{Dataset, Graph, Description}
 
   @doc """
   Encodes and writes a graph or dataset to a string.
@@ -15,7 +15,7 @@ defmodule RDF.Serialization.Writer do
   It returns an `{:ok, string}` tuple, with `string` being the serialized graph or
   dataset, or `{:error, reason}` if an error occurs.
   """
-  @spec write_string(module, Graph.t() | Dataset.t(), keyword) ::
+  @spec write_string(module, Description.t() | Graph.t() | Dataset.t(), keyword) ::
           {:ok, String.t()} | {:error, any}
   def write_string(encoder, data, opts \\ []) do
     encoder.encode(data, opts)
@@ -26,7 +26,7 @@ defmodule RDF.Serialization.Writer do
 
   As opposed to `write_string`, it raises an exception if an error occurs.
   """
-  @spec write_string!(module, Graph.t() | Dataset.t(), keyword) :: String.t()
+  @spec write_string!(module, Description.t() | Graph.t() | Dataset.t(), keyword) :: String.t()
   def write_string!(encoder, data, opts \\ []) do
     encoder.encode!(data, opts)
   end
@@ -43,7 +43,8 @@ defmodule RDF.Serialization.Writer do
 
   It returns `:ok` if successful or `{:error, reason}` if an error occurs.
   """
-  @spec write_file(module, Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok | {:error, any}
+  @spec write_file(module, Description.t() | Graph.t() | Dataset.t(), Path.t(), keyword) ::
+          :ok | {:error, any}
   def write_file(encoder, data, path, opts \\ []) do
     with {:ok, encoded_string} <- write_string(encoder, data, opts) do
       File.write(path, encoded_string, file_mode(encoder, opts))
@@ -57,7 +58,7 @@ defmodule RDF.Serialization.Writer do
 
   As opposed to `write_file`, it raises an exception if an error occurs.
   """
-  @spec write_file!(module, Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok
+  @spec write_file!(module, Description.t() | Graph.t() | Dataset.t(), Path.t(), keyword) :: :ok
   def write_file!(encoder, data, path, opts \\ []) do
     with encoded_string = write_string!(encoder, data, opts) do
       File.write!(path, encoded_string, file_mode(encoder, opts))

lib/rdf/serializations/turtle_encoder.ex

@@ -36,7 +36,8 @@ defmodule RDF.Turtle.Encoder do
   @ordered_properties MapSet.new(@predicate_order)
 
   @impl RDF.Serialization.Encoder
-  @spec encode(Graph.t() | Dataset.t(), keyword) :: {:ok, String.t()} | {:error, any}
+  @spec encode(Description.t() | Graph.t() | Dataset.t(), keyword) ::
+          {:ok, String.t()} | {:error, any}
   def encode(data, opts \\ []) do
     base =
       Keyword.get(opts, :base, Keyword.get(opts, :base_iri))

test/unit/turtle_encoder_test.exs

@@ -289,6 +289,13 @@ defmodule RDF.Turtle.EncoderTest do
     end
   end
 
+  test "serializing a description" do
+    description = EX.S |> EX.p(EX.O)
+
+    assert Turtle.Encoder.encode!(description) ==
+             description |> Graph.new() |> Turtle.Encoder.encode!()
+  end
+
   describe "serializing a dataset" do
     test "prefixes of the graphs are merged properly" do
       dataset =