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Re: Re: Re: Types in Mathematica

  • To: mathgroup at
  • Subject: [mg62886] Re: [mg62879] Re: [mg62805] Re: Types in Mathematica
  • From: Zhengji Li < at>
  • Date: Thu, 8 Dec 2005 00:04:12 -0500 (EST)
  • References: <dlp2ci$le$> <dls4vp$mmc$> <dm1ak3$i1n$> <dmjrb8$5u6$> <dmm2tp$nmo$> <dmrt6i$6le$> <> <dmui9j$ml5$> <> <>
  • Sender: owner-wri-mathgroup at

Such a hot topic here.

But what does "type" mean on earth?

I define an integer "i". Then I do some arithmetic with it. Here,
"i"'s type is "integer".

In a programming language (like C), I write:
int i;  i = 1234;

As the programmer, I do not care how the language implements
"integer". It can use a register, or several bytes in memory (the
ASCII code of "1234", or in Binray Code Decimal) to represent it.

Let me guess, "types" should be considered in two layers: abstract 
layer and phsical layer.

An integer "i" on abstract layer can be represented as an integer in
tradition meaning or something else as you like on phyiscal layer.

When I got a string "1234" on phsical layer, I can "abstract" it to an
integer 1234. This is the mapping of types between the two layers.

Turn to Mathematica, I define a symbol "a", it is completely a
"symbol", it can be anything. This may be a try of Mathematica to
represent things on the abstract layer.

Li Zhengji
If all you have is a hammer, everything is a nail.

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