If obj is not a port returns false, otherwise returns a symbol describing the port type, for example string or pipe.
Returns the filename port was opened with. If port is not open to a file the result is unspecified.
Sets the current position in port which will next be read or written. If successful,
#fis returned. If port is open to a non-file, then
If port is a tracked port, return the current line (column) number, otherwise return
#f. Line and column numbers begin with 1. The column number applies to the next character to be read; if that character is a newline, then the column number will be one more than the length of the line.
Outputs a newline to optional argument port unless the current output column number of port is known to be zero, ie output will start at the beginning of a new line. port defaults to
current-output-port. If port is not a tracked port
freshlineis equivalent to
#tif a character is ready on the input port and returns
#tthen the next
read-charoperation on the given port is guaranteed not to hang. If the port is at end of file then
#t. Port may be omitted, in which case it defaults to the value returned by
Char-ready?exists to make it possible for a program to accept characters from interactive ports without getting stuck waiting for input. Any input editors associated with such ports must ensure that characters whose existence has been asserted by
char-ready?cannot be rubbed out. If
char-ready?were to return
#fat end of file, a port at end of file would be indistinguishable from an interactive port that has no ready characters.