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Re: Re: Programming style: postfix/prefix vs. functional

  • To: mathgroup at
  • Subject: [mg70661] Re: [mg70633] Re: [mg70587] Programming style: postfix/prefix vs. functional
  • From: Murray Eisenberg <murray at>
  • Date: Sun, 22 Oct 2006 01:20:13 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <> <>
  • Reply-to: murray at

@ is an abbreviation for Composition:

   Composition[f, g][expr]


But this one is a bit difficult to discover from the documentation.  If 
you know the term "Composition", then of course you can do the reverse 
look-up in the Help Browser.

Unfortunately, if you try the Help Browser directly for "@", even using 
the Master Index tab, you won't find it!

Moreover, if you try the default Built-in Functions tab you search for 
@, you'll be taken to the entry for Apply (@@).

So this is definitely a gap in the documentation indexing.

Chris Chiasson wrote:
> One thing I have wondered is, what function corresponds to the short
> hand "@". I know @ appears in Operate. Also, the ? can sometimes tell
> what function an operator represents (try ?/@ ) , but ?@ only gives
> System`$ (the symbol $ in the context System).
> On 10/20/06, Will Robertson <wspr81 at> wrote:
>> Hello,
>> As a newcomer to Mathematica, I'm a little unsure on what "good style"
>> would be in this programming language. I notice that several functions
>> have prefix and postfix notations such as //. for ReplaceRepeated, /@
>> for Map, and so on.
>> Clearly using these forms makes the code more compact, but sacrifices
>> some level of readability. Are there guidelines or suggestions that
>> have built up over the years of whether these are "good" or "bad" to
>> use?
>> If it's simply personal preference, what do you like to use?
>> --
>> Many thanks,
>> Will Robertson

Murray Eisenberg                     murray at
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

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