As it turns out, changing the color (via change-style) can somtimes
split snips, which can change the revision number, which means that
the open port into the editor is no longer valid.
Since this doesn't seem to happen very much when editing in DrRacket,
we just detect this situation and give up on this colorer's port, and
hopefully it actually doesn't happen much (the place it happened that
let me notice this was when inserting an image via a menu in the
drracket test suites)
refactor it so it doesn't add anything to the continuation ever, and
just check if it has been a while since we started (giving other
events a chance to run, if so). Also, interleave the calls to
change-style with the parsing of the buffer to get a more accurate
count of the time the colorer is taking
Shape information allows the linker to check the importing
module's compile-time expectation against the run-time
value of its imports. The JIT, in turn, can rely on that
checking to better inline structure-type predicates, etc.,
and to more directy call JIT-generated code across
module boundaries.
In addition to checking the "shape" of an import, the import's
JITted vs. non-JITted state must be consistent. To prevent shifts
in JIT state, the `eval-jit-enabled' parameter is now restricted
in its effect to top-level bindings.
Updated example for for/digits to avoid confusion: it's not clear
otherwise that the intentional syntax error wasn't just a casual
mistake.
Added an example for sequence-add-between.
so that it waits until online check syntax actually
finishes (otherwise, there actually is a leak;
the link is broken when the message comes back from the
other place)
This tracking allows the compiler to treat structure sub-type
declarations as generating constant results, and it also allows
the compiler to recognize an applications of a constructor or
predicate as functional.
