From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <4AC9D739.5040504@maht0x0r.net>
Date: Mon,  5 Oct 2009 12:23:37 +0100
From: matt <maht-9fans@maht0x0r.net>
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To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
References: <20091003191118.GD15021@nipl.net>	<45a41ae73e4adf6d1b38fe9c31977c52@proxima.alt.za>	<20091004071748.GA16895@nipl.net>
	<140e7ec30910040359q28c30ea2re5185846042cf43a@mail.gmail.com>
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Subject: Re: [9fans] mishandling empty lists - let's fix it
Topicbox-Message-UUID: 7ea94410-ead5-11e9-9d60-3106f5b1d025

sqweek wrote:

>
>fn apply {
>    cmd=$1
>    shift
>    while(! test $1 = :) {
>        cmd=($cmd $1)
>        shift
>    }
>    for(i in $*) $cmd <$i
>}
># eg: apply grep foo : *.c
>
>
>

that's the beauty of the rc shell, you can define what you like

fn cat {
    if(~ $#* 0)
        /bin/cat /dev/null
    if not {
       as = ()
       for(a in $*) {
          if(~ $a -)
             as = ($as /fd/0)
          if not
             as = ($as $a)
       }
       /bin/cat $as
    }
}

now
% echo test | cat
% echo test | cat -
test
%  cat  /lib/words | sed 1q
AAA
%

If your shell programs are defeated by unexpected empty lists I suggest
you write better shell programs :)