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MathGroup Archive 1998

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Re: [Q] How to get rid of {} ???


  • To: mathgroup@smc.vnet.net
  • Subject: [mg10726] Re: [Q] How to get rid of {} ???
  • From: "P.J. Hinton" <paulh@wolfram.com>
  • Date: Mon, 2 Feb 1998 00:44:20 -0500
  • Organization: Wolfram Research, Inc.
  • References: <6as8tj$f7i@smc.vnet.net>

On 30 Jan 1998, Alessandro Rossi wrote:

> Hi everyone again...
> I'm just curious to ask if is it possible to get rid of the {} simbols
> in a plain list of this kind {a1, a2, a3, ..., an} when you want to use
> the ordered sequence of a1, a2, a3, ..., an as arguments for a
> function.
> 
> e.g.
> l
> 
> 
> If I have the following list:
> list={True, False, True}
> 
> how can I computethe And Function of the three arguments of list:
> 
> And[True, False, True]
> 
> obviously 
> 
> And[list]
> 
> doesn't work...
> 
> It seems to me a very simple problem, but at the same time I really can
> not solve it. Any samaritan willing to give me some indication to solve
> this "Columbus Egg"???

	And[Evaluate[Sequence @@ list]]

The use of Apply (@@) converts the List into a Sequence.  Because the
And function has the attribute HoldAll, you have to throw an Evaluate
wrapper around the argument.

--
P.J. Hinton
Mathematica Programming Group           paulh@wolfram.com Wolfram
Research, Inc.                  http://www.wolfram.com/~paulh/
Disclaimer: Opinions expressed herein are those of the author alone.




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