de.sciss.lucre

An artifact is a file on an external storage.

An artifact location is a directory on an external storage.

An expression is a computation that reduces to a single value of type A. Expressions can be understood as data-flow variables. When a tree is composed, a change in the root of the tree propagates through to the leaves in the form of an emitted Change event that carries the old and new value (according to the particular node of the tree).

Basic expression types are Expr.Const - it simply wraps a constant value and thus will never change or fire an event - and Expr.Var which can be thought of as a mutable variable carrying a peer expression. When the variable assignment changes, the expression currently held is evaluated and propagated as an event. Intermediate nodes or expressions might modify the value, such as a binary operator (e.g., an integer expression that sums two input integer expressions).

An observable linked list with fast head and last operations. This is the read-only layer, see List.Modifiable for a mutable list.

The list will report insertions and deletions.