Re: #\EOF

[David A. Moon <MOON at MIT-MC>]

    Date: 26 SEP 1980 2317-EDT
    From: KMP at MIT-MC (Kent M. Pitman)
    ...
    The :TYI operation is documented to return () iff the end-of-file value
    requested is not given or is (). I would like a fixnum value that I can
    feed as the end-of-file value which is not in the character set. I hope
    that :TYI will not force a () on me if I specify the 2nd arg to that
    operation.
I don't know what document you're reading, this is not what the Lisp
machine manual which I would assume to be the definitive document on
Lisp machine streams says.

The problem with having a "character" called #\EOF is that not
all sources of characters want to indicate EOF in the same way.
If it wasn't for the unfortunate presence of data types in Maclisp,
such that TYI must always return a fixnum, I would advocate making
NIL the end of file indication in everything, since it is clearly
not a character and is the standard indicator of emptiness.

Under the circumstances I think it would be misleading and confusing
to introduce a "#\EOF" syntax because it would only work with some
and not all functions.