f over all tree nodes, in depth-first, prefix order
f over all tree nodes, in depth-first, prefix order, but don't visit
f returns a different result for the root, i.e.
f(x, root) ne x.
A class for copying trees. The copy methods avoid creating a new tree If all arguments stay the same.
Note: Some of the copy methods take a context. These are exactly those methods that are overridden in TypedTreeCopier so that they selectively retype themselves. Retyping needs a context.
For untyped trees, this is just the identity.
For typed trees, a context derived form
ctx that records
call as the
innermost enclosing call for which the inlined version is currently