Racket v8.16 draft release notes

[shhyou]

I recommend this PR by @mike: https://github.com/racket/htdp/pull/222
I think the debugger support of menu-based ASL has been there for a long time, but #lang htdp/asl previously didn't get the "Debug" button.

Maybe this?

• #lang htdp/asl incorporates Graphical Debugger support.

@jbclements

A revised representation of pointers makes ptr-ref and ptr-set!
substantially faster, reducing the overhead of foreign function
calls.

How about focusing on FFI calls in general? like

• A revised representation of pointers improves the performance of foreign function calls.
  • ptr-ref and ptr-set! are substantially faster.

Just for the record, this post details the FFI improvement (with several benchmarking results from @mflatt and @pavpanchekha):
https://racket.discourse.group/t/fixnum-slow-despite-docs/3409/6

@jbclements

• A variety of new treelist utility functions are available:
  treelist-filter, treelist-flatten, et cetera.
• The mutable-treelist-prepend! function allows prepending to
  mutable treelists.
• Mutable treelists are serializable.

Does it make sense to make them a secondary-level list and summarize the notes as one top-level item? (e.g.

• Expanded support for immutable and mutable treelists.
  • ...
  • ...)

@jbclements

• The open-input-nowhere function creates an empty input port.
• The pipe-port? function makes it possible to determine whether a port is connected to a pipe.
• The port-file-stat function allows gathering information about the file that is the source or target of a file-stream port.

These items fall under the general "port I/O" category. Similar to the treelist items, I wonder whether grouping them under a top-level "new port I/O functions"-ish item better structures the release notes.