R7RS provides u8-ready? and char-ready?    (a non-blocking check for more input available or EOF)

...but these custom ports do not provides hooks to implement them.

On Sun, Feb 16, 2020 at 3:03 AM Arthur A. Gleckler <xxxxxx@speechcode.com> wrote:
Scheme Request for Implementation 181,
"Custom ports,"
by John Cowan,
is now available for discussion.

Its draft and an archive of the ongoing discussion are available at https://srfi.schemers.org/srfi-181/.

You can join the discussion of the draft by filling out the subscription form on that page.

You can contribute a message to the discussion by sending it to xxxxxx@srfi.schemers.org.

Here's the abstract:

This is an extract from the R6RS that documents its support for custom ports. These provide a hook into the Scheme port system from below, allowing the creation of binary and textual ports that behave exactly like file, string, and bytevector ports, but whose basic operations are provided by user code. It has been lightly edited to fit R7RS style.


SRFI Editor