λδ comes in several versions listed in the following table,
which includes the major milestones:
The λδ Digital Library is part of
HELM
and contains resources expressed in λδ.
Helena is a λδ processor,
implemented in
Caml
as a part of the
HELM software,
meant for testing the stable features of the calculus as well as the unstable ones.
The processor source code is available in the directory
/trunk/helm/software/helena/
of the
HELM Svn repository.
The Svn revisions containing the stable versions of Helena are indicated next.