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Re: Re: Programming style: postfix/prefix vs. functional
*To*: mathgroup at smc.vnet.net
*Subject*: [mg70673] Re: [mg70633] Re: [mg70587] Programming style: postfix/prefix vs. functional
*From*: "Chris Chiasson" <chris at chiasson.name>
*Date*: Mon, 23 Oct 2006 02:49:38 -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> <2F11E8C9-D5C5-45EC-BA91-7F52E72CCC3B@mimuw.edu.pl>
On 10/21/06, Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote:
> 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 @@@ ...
But we know that @@ and @@@ correspond to Apply at level specification
{0} and {1}, respectively. We also know that /@ and //@ correspond to
Map at level specification {1} and {0,Infinity} (or just MapAll). It
seems to me that @ is the odd one out, because it doesn't "correspond
to a particular function".
On 10/21/06, Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote:
> 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/
>
>
--
http://chris.chiasson.name/
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