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Re: Re: More /.{I->-1} craziness

• To: mathgroup at smc.vnet.net
• Subject: [mg106143] Re: [mg106058] Re: [mg106017] More /.{I->-1} craziness
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Sat, 2 Jan 2010 05:08:29 -0500 (EST)
• References: <200912300915.EAA17299@smc.vnet.net> <200912310818.DAA24919@smc.vnet.net>

On 31 Dec 2009, at 17:18, Leonid Shifrin wrote:

> I think that there are not many more objects in Mathematica which are as
> tricky as <I> or Infinity in terms of pattern-matching.

Another obvious case that can be included is Rational, e.g.

Head[2/3]

Rational

Head[Unevaluated[2/3]]

Times

Head[a/b]

Times

AtomQ[2/3]

True

AtomQ[a/b]

False

Rational works essentially the same way as Complex.

It's perfectly consistent, fully justified, and certainly will never be changed.

Andrzej Kozlowski