Bug: nft cannot identify elements in set correctly

[Yanchuan Nian <ycnian@gmail.com>]

nft cannot identify elements in set correctly, look at the result of
following commands.

[root@localhost ~]# nft add set ip filter servicelist {type inet_service \;}
[root@localhost ~]# nft add element ip filter servicelist {ftp,ssh}
<cmdline>:1:35-37: Error: syntax error, unexpected string, expecting '{'
add element ip filter servicelist ftp ssh
                                  ^^^
[root@localhost ~]# nft add element ip filter servicelist {ftp, ssh}

There must be a space between ftp and ssh, otherwise bison ignores "{".
But it's strange that this bug doesn't exist in interactive mode.

[root@localhost nftables]# nft -i
nft> delete element ip filter servicelist {ftp,ssh}
nft> add element ip filter servicelist {ftp,ssh}
nft> 
nft> list table ip filter
table ip filter {
	set servicelist { 
		type inet_service
		elements = { ssh, ftp}
	}
}
nft> 

What's the difference between shell mode and interactive mode? I thought
they are the same except you don't need to type "nft" at the beginning
of each command in interactive mode.