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Library semantics correction
With the semantics as stated in the document, a library will only ever
be visited at phase 0, so a recursion step seems to be missing. Indeed,
the following example is not covered:
(library "m" "scheme"
(define-syntax u (lambda (exp) (syntax 1)))
(library "n" "scheme"
(import (for "m" syntax))
(define-syntax v (lambda (exp) (u)))
Indeed, visiting "n" at phase 0 requires "m" to be visited at phase 1 (because
there is a reference to the macro u on the right hand side of the
definition of v.
Here is what I think needs to be added:
To visit a library at phase N:
* Visit at phase N any library that is imported by this library for run time,
and that is not yet visited at phase N.
* Invoke at phase N+1 any library that is imported by this library for .... expand,
and that is not yet invoked at phase N+1.
* Visit at phase N+1 any library that is imported by this library
for .... expand, and that is not yet visited at phase N+1.
* Evaluate all syntax definitions within the library.
(Top-level expressions are not evaluated, and the right-hand sides
of variable definitions are not evaluated.)