

Five Dollar Programming Words - bdfh42
http://www.codinghorror.com/blog/archives/001244.html

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extension
_Sciolist_

One who knows many things superficially; a pretender to science; a smatterer

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Hexstream
"A function is "idempotent" if the result of doing it twice ( _feeding the
output of the first call into the second call_ ) is exactly the same as the
result of doing it once. (Or, in other words, every output of the function is
idempotent under it.)"

Uh?? According to this definition this wouldn't be idempotent:

    
    
      (defun add-one (x)
        (+ x 1))
    
      CL-USER> (values (add-one 5)
               (add-one (add-one 5))
               (= (add-one 5) (add-one (add-one 5))))
      6
      7
      nil
    

edit: What the... Wikipedia seems to be agreeing with him. It seems I mixed up
idempotence and referential transparency, I thought they were equivalent
concepts. I'm confused...

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jcromartie
I think Jeff conveys the wrong sense of idempotence. He has somehow extracted
the purely mathematical sense, while the source he quotes goes on to explain
the programming angle.

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gamache
Yeah, I had never heard 'idempotence' used in a mathematical sense before. I
just think of that as a function hitting a fixed point.

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viggity
I really do like Jeff Atwood, I think for the most part he has been beneficial
to the community. But for the love of god, I wish he would stop making half of
his post quotes from someone else's post. I don't mind that he gets an idea to
write something based off of another person, but he could at least add
something substantive to it.

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iron_ball
I see him as a sort of Reader's Digest of programming. Not sure if that's
good, mind you.

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biohacker42
Reader's Digest of programming is the perfect description!

