# This function writes all non-NULL global variables to a file.  This
# can be used, for example, to save an Algae session that you wish to
# start again later.  (See the `load' function.)

save = function( file )
{
    local( r; t; name );

    t = $$;
    r = {};
    for ( name in members( t ) )
    {
        if ( t.(name) == NULL ) { r.(name) = NULL; }
    }
    t -= r;

    return put( t; file );

};