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Re: Any uses for SequenceHold ?


> Mma 3.0 has a new Attribute called SequenceHold.
> As far as I can tell this Attribute has no useful application.
> 
> In what way would things fail to work if these function didn't have this 
> Attribute?
> 
> How did ealier versions get by without SequenceHold?
> 
>                Ted Ersek
>                ersek_ted%pax1a at mr.nawcad.navy.mil

Here is Version 3.0:

In[2]:= {x, y, z} /. y -> Sequence[y1, y2, y3]

Out[2]= {x, y1, y2, y3, z}

This works because Rule has the SequenceHold attribute.i
In Version 2.2 this generates an error message and fails.

Dave Withoff
Wolfram Research


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