! Copyright (C) 2010 Benjamin Meinl.
! See http://factorcode.org/license.txt for BSD license.

! Library to calculate your average grade

USING: kernel io prettyprint math.parser
    math math.statistics make ;
IN: grades

: read-number ( -- number/f )
    readln string>number ;

: read-grades ( -- grades ) [ [
            read-number [ [ , ] when* ] keep
        ] loop
    ] { } make ;

: main ( -- )
    "Enter grades, or nothing to stop:" print
    read-grades mean >float . ;

MAIN: main