Scieneer Common Lisp 1.3.9 online documentation

ext:stream-write-byte-no-hang stream byte[Generic Function]

Writes byte to the stream if the write will not block and returns the byte. Otherwise return nil without waiting. The default method calls ext:stream-write-byte which should be fine for a file stream, however unbuffered binary output socket streams will probably want to defined a method for this function. When a byte is not written the function ext:stream-waiting-file-descriptor may be called to find the file descriptor and directions blocked and when ready the function may be called again to continue the operation.