Returns either a character from the stream, an :eof
if the end-of-file is reached, or nil
if no input is currently available.
The generic function stream-read-char-no-hang
implements read-char-no-hang
. It returns either a character read from the stream, or:eof
if end-of-file is reached, or nil
if no input is available. The default method provided by fundamental-character-input-stream
simply calls stream-read-char
which is sufficient for file streams, but interactive streams should define their own method.
LispWorks User Guide and Reference Manual - 13 Feb 2015