Recent work on the DOT calculus successfully put core aspects of Scala
on a sound foundation, but subtyping in DOT is structural and therefore not
easily amenable to studying the parts of Scala that are deeply tied to its nominal subtyping
system. On the other hand, the Featherweight Java calculus has proven to be a
great basis for studying many aspects of Java and Java-like languages.
Continuing this tradition, we present Pathless Scala: an extension of
Featherweight Generic Java that closely models multiple inheritance and
intersection types as they exist in the Scala language today. We define the
semantics of Pathless Scala by erasing it to a simpler calculus in a way that
closely models how Scala is compiled to Java bytecode in practice. More than a
one-off, we believe that this calculus could be extended to describe many
more features of Scala, although reconciling it with DOT remains an open
problem.

PhD student at EPFL in the LAMP group working on the Scala 3 compiler