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

• To: mathgroup at smc.vnet.net
• Subject: [mg70647] Re: [mg70633] Re: [mg70587] Programming style: postfix/prefix vs. functional
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Sun, 22 Oct 2006 01:19:24 -0400 (EDT)
• References: <200610200921.FAA11092@smc.vnet.net> <200610210914.FAA29189@smc.vnet.net> <2A8E209D-C4D9-45C1-933B-5E3D955D99C5@mimuw.edu.pl> <acbec1a40610210543k3a861eb7tb3bdb777170618b@mail.gmail.com>

Well, I would say that f@x is just a "shorthand" for f[x] and does  
not "correspond" to any function. It seems to me that same applies to  
@@ and to @@@ and none of these cases ? will yield any information.  
In fact, ? itself works in a curious way. Sometimes it corresponds to  
the function Information; as in

Information[Sin]

which is the same as ?Sin. But in some cases, notably ?@ you can't  
use Information; this
Information[@]  does not parse correctly (I think this is the right  
way to use "parse" ;-)), in other words, it is not syntactically  
correct. So ? seems actually work in two different ways: as another  
way to input Information but also rather like the symbol ! in front  
of a file name, which displays the contents of the file on the screen  
and does not correspond to any Mathematica function.

Andrzej Kozlowski


On 21 Oct 2006, at 21:43, Chris Chiasson wrote:

> Andrzej Kozlowski,
>
> Thanks for the wildcard info!
>
> So, does @ correspond to Operate? I think Operate is a bit different
> than @, but I am not sure.
>
> On 10/21/06, Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote:
>> (tm) Pro*
>>
>> On 21 Oct 2006, at 18:14, 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).
>>
>> That's because the symbol @ already has another meaning as a "wild
>> card":
>>
>> @ , one or more characters excluding upper$B!>(Bcase letters
>>
>> (A more general wild card is, of course *). So ?@ returns all the
>> symbols defined in the  contexts  of the current session that do not
>> contain capital letters. Evaluate some symbols whose names contain
>> only small letter in Mathematica and try ?@ again to see this in  
>> action.
>>
>> Andrzej Kozlowski
>>
>>
>> >
>> >
>> > On 10/20/06, Will Robertson <wspr81 at gmail.com> 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
>> >>
>> >>
>> >
>> >
>> > --
>> > http://chris.chiasson.name/
>> >
>>
>>
>
>
> -- 
> http://chris.chiasson.name/

• References:
  • Programming style: postfix/prefix vs. functional
    • From: "Will Robertson" <wspr81@gmail.com>
  • Re: Programming style: postfix/prefix vs. functional
    • From: "Chris Chiasson" <chris@chiasson.name>