drain-input

[Alex Shinn]

Could someone explain the purpose of drain-input?  My first impression
was that it would read all remaining input from an input port, so that
you could do the following:

(define (file-contents file)
  (call-with-input-file file drain-input))

but this doesn't work, and on playing with drain-input it seems to be
working more with the internal port buffering.  For example:

(define p (open-input-file foo))   ; str is
(define str (drain-input p))       ; ""
(unread-char #\x p)
(set! str (drain-input p))         ; "x"
(set! str (drain-input p))         ; ""
(peek-char p)
(set! str (drain-input p))         ; entire contents of foo

Is this the correct behaviour?  What is drain-input really doing?

-- 
Alex Shinn <address@hidden>