Revise some module docs

lib/rdf/blank_node.ex

@@ -1,6 +1,6 @@
 defmodule RDF.BlankNode do
   @moduledoc """
-  An RDF blank node, also known as an anonymous or unlabeled node.
+  A RDF blank node is a local node of a graph without an URI.
 
   see <https://www.w3.org/TR/rdf11-primer/#section-blank-node>
   and <https://www.w3.org/TR/rdf11-concepts/#section-blank-nodes>

lib/rdf/dataset.ex

@@ -1,9 +1,18 @@
 defmodule RDF.Dataset do
   @moduledoc """
-  Defines a RDF Dataset.
+  A set of `RDF.Graph`s.
+
+  It may have multiple named graphs and at most one unnamed ("default") graph.
+
+  `RDF.Dataset` implements:
+
+  - Elixirs `Access` behaviour
+  - Elixirs `Enumerable` protocol
+  - Elixirs `Inspect` protocol
+  - the `RDF.Data` protocol
 
-  A `RDF.Dataset` represents a set of `RDF.Dataset`s.
   """
+
   defstruct name: nil, graphs: %{}
 
   @behaviour Access

lib/rdf/description.ex

@@ -1,9 +1,15 @@
 defmodule RDF.Description do
   @moduledoc """
-  Defines a RDF Description.
+  A set of RDF triples about the same subject.
 
-  A `RDF.Description` represents a set of `RDF.Triple`s about a subject.
+  `RDF.Description` implements:
+
+  - Elixirs `Access` behaviour
+  - Elixirs `Enumerable` protocol
+  - Elixirs `Inspect` protocol
+  - the `RDF.Data` protocol
   """
+
   defstruct subject: nil, predications: %{}
 
   @behaviour Access

lib/rdf/graph.ex

@@ -1,11 +1,16 @@
 defmodule RDF.Graph do
   @moduledoc """
-  Defines a RDF Graph.
+  A set of RDF triples with an optional name.
 
-  A `RDF.Graph` represents a set of `RDF.Description`s.
+  `RDF.Graph` implements:
+
+  - Elixirs `Access` behaviour
+  - Elixirs `Enumerable` protocol
+  - Elixirs `Inspect` protocol
+  - the `RDF.Data` protocol
 
-  Named vs. unnamed graphs ...
   """
+
   defstruct name: nil, descriptions: %{}
 
   @behaviour Access

lib/rdf/quad.ex

@@ -1,9 +1,9 @@
 defmodule RDF.Quad do
   @moduledoc """
-  Defines a RDF Quad.
+  Helper functions for RDF quads.
 
-  A Quad is a plain Elixir tuple consisting of four valid RDF values for
-  subject, predicate, object and a graph context.
+  A RDF Quad is represented as a plain Elixir tuple consisting of four valid
+  RDF values for subject, predicate, object and a graph context.
   """
 
   alias RDF.{BlankNode, Statement}

lib/rdf/statement.ex

@@ -1,6 +1,6 @@
 defmodule RDF.Statement do
   @moduledoc """
-  Defines a RDF Statement.
+  Helper functions for RDF statements.
 
   A RDF statement is either a `RDF.Triple` or a `RDF.Quad`.
   """

lib/rdf/triple.ex

@@ -1,9 +1,9 @@
 defmodule RDF.Triple do
   @moduledoc """
-  Defines a RDF Triple.
+  Helper functions for RDF triples.
 
-  A Triple is a plain Elixir tuple consisting of three valid RDF values for
-  subject, predicate and object.
+  A RDF Triple is represented as a plain Elixir tuple consisting of three valid
+  RDF values for subject, predicate and object.
   """
 
   alias RDF.{BlankNode, Statement}