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Re: Replace and ReplaceAll -- simple application

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  • Subject: [mg106123] Re: Replace and ReplaceAll -- simple application
  • From: Richard Fateman <fateman at>
  • Date: Sat, 2 Jan 2010 05:04:36 -0500 (EST)
  • References: <hhkjce$5aq$>

Bill Rowe wrote:

> Do you have some definition for "bug" other than performance in
> a manner different than documented?


> That is, failure of any software to do what a user expects is
> certainly not a bug if that is what the software is documented
> to do.


Here's why.  By your definition, no program has a bug if the programmer
asserts that the program, by virtue of being written in a high-level 
language, is its own readable documentation. Therefore anything that
the program does is documented by its own code and therefore is not a bug.

or in the immortal words of Peewee Herman "I meant to do that".

> The key problem here is a novice user of Mathematica might think
> of using replacement rules as doing mathematics.

Maybe he was confused by the title
"Mathematica -- A System for Doing Mathematics",  and thought that
Mathematica was a system for doing mathematics.

  That simply
> isn't the case.

Apparently you thought that Mathematica was "A system for doing 
rule-based syntactic transformations on FullForm expressions which may 
or may not correspond to what is displayed"

  And since replacing one thing with another is
> not mathematics, insisting the result makes sense mathematically
> simply isn't a realistic expectation.

TaDa.  I couldn't have expressed it better myself.  Insisting that the 
results of a transformation is mathematically consistent, "isn't a 
realistic expectation."

Which, in my view, demonstrates the existence of a bug.

  I suppose one could try to determine who is right by a survey,  or ask 
people in the street what they think.



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