Banana-RDF for Scala 3

This project is porting banana-rdf to Scala3.

Thanks to the financial help by NlNet in the solid-control project.

Artifacts

Artifacts can be found in the sonatype repository https://oss.sonatype.org/content/repositories/snapshots/net/bblfish/rdf/

Changes from banana-rdf 0.8

Scala 3 comes with many new features, but dropped one too.

Match Types

The most important dropped features we were relying on was type projections. We replace those with match types. As a result code where we used to have (see 0.8.x GraphTest)

val foo1gr: Rdf#Graph = Graph(Triple(exuri(), rdf("foo"), Literal("foo")))

we now have (see GraphTest)

val foo1gr: Graph[Rdf] = Graph(Triple(exuri(), rdf("foo"), Literal("foo")))

Relative Uris, Triples and Graphs

We also make heavy use of opaque types. This allows us to keep the distinction between relative URLs (rURI), triples (rTriple) and Graphs (rGraph) and the usual graphs understood by RDF with absolute urls. The type distinction we make in RDF is then also translated by differences in the operations allowed. For example operations.rGraph do not allow the union of two rGraphs but do have a method to resolve an rGraph against an AbsoluteUrl. On the other hand the operations.Graph allow one to take the union of two Graph[Rdf]. They have no method resolveAgainst but do have a method relativizeAgainst which produces an rGraph.

Making relative URLs more clearly visible in the type system makes it easier to write parsers and serialisers, since those do contain relative URLs.

Discussions

Some places where ideas have been discussed are:

• replacing projection types
• Algebras of opaque types and pattern matching

Usage

This is a normal sbt project, you can compile code with sbt compile and run it with sbt run, sbt console will start a Dotty REPL.