get-line, read-line - read a line from a port

---

LIBRARY

(import (rnrs))                     ;R6RS
(import (rnrs io ports))            ;R6RS
(import (scheme base))              ;R7RS

SYNOPSIS

(get-line textual-input-port)       ;R6RS
(read-line)                         ;R7RS
(read-line textual-input-port)      ;R7RS

DESCRIPTION

If a linefeed character is read then a string containing all of the text up to (but not including) the linefeed character is returned, and the port is updated to point just past the linefeed character.

If an end of file is encountered before any linefeed character is read, but some characters have been read and decoded as characters, then a string containing those characters is returned.

If an end of file is encountered before any characters are read, the end-of-file object is returned.

R6RS

If the port's end-of-line style is not none then all line endings will be read as linefeed characters.

R7RS

For the purpose of this procedure, an end of line consists of either a linefeed character, a carriage return character, or a sequence of a carriage return character followed by a linefeed character. Implementations may also recognize other end of line characters or sequences.

The default value for textual-input-port is the value returned by current-input-port(3scm).

RETURN VALUES

EXAMPLES

;; Return all records in /etc/passwd
(with-input-from-file "/etc/passwd"
  (lambda ()
    (let lp ()
      (let ((line (get-line (current-input-port))))
         (if (eof-object? line)
             '()
             (cons line (lp)))))))

APPLICATION USAGE

COMPATIBILITY

The R7RS variant essentially works as if ports can only have eol-style none and moves the recognition of linefeeds into the read-line procedure. This also implies that read-char (3scm) should return each character that makes up a linefeed sequence, such as carriage return followed by linefeed.

R6RS has a single end-of-file object, but R7RS implementations may have several.

ERRORS

&i/o-read (R6RS)

There was a read error that occurred during an I/O operation.

&assertion (R6RS)

The wrong number of arguments was passed or an argument was outside its domain.

R7RS

The situations described above are errors. Implementations may signal an error, extend the procedure's domain of definition to include such arguments, or fail catastrophically.

SEE ALSO

STANDARDS

HISTORY

AUTHORS