Re: Appending an element to a list

• To: mathgroup at smc.vnet.net
• Subject: [mg23939] Re: Appending an element to a list
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 16 Jun 2000 00:57:24 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <8i9nta\$27l@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

the good old If[] is not working any more ?

If[d=!={},
AppendTo[list,d]
]

AppendTo[list,d] /. {}-> Sequence[]

is broken too ?
The pattern matcher don't work with

myAppend[lst_, {}] := lst
myAppend[lst_, ll_] := Append[lst, ll]

lst=myAppend[lst,d]

Than I have no idea
Regards
Jens

Felix Farkas wrote:
>
> Hello,
>  i do have a problem, which is probably very easy,  but i couldn't find
> a reasonable way to solve it. I would appreciate very much any hint.
>
> I have a list of lists. My purpose is to append a new elements to this
> list. These elements are generated by some function. Sometimes the
> output of the function is an empty list meaning no element. In this
> situation Append includes the new element in the list. i would like to
> avoid this behaviour.
>
> ex:
>
> In[1]:=           d={}
> Out[1]=         {}
>
> In[2]:=           Append[{{2,2},{3,3}},d]
> Out[2]:=        {{2,2},{3,3},{}}
>
> Thanks in advance. Felix Farkas

```

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