Hi!
Well [1 2 3] is just a syntaxic sugar for (vector 1 2 3):
=>(vector 1 2 3)
[1 2 3]
When you enter a vector in the repl, it is evaluted to itself. Here an
example that show it:
=>[1 2 (+ 1 2)]
[1 2 3]
And you can use the vector function for the same result:
=>(vector 1 2 (+ 1 2))
[1 2 3]
The quote prevent evaluation but this is not specific to lists:
=>'[1 2 (+ 1 2)]
[1 2 (+ 1 2)]
The way to make function calls in lisp (and in clojure) is to consider
the first element of the list to be the function, and the next one to
be the argument of the function. This what happen when you perform say
an addition
(+ 1 2) is a call to the add function with 2 parameters.
But this mean that you can't define a list (data structure) just by
writing it, because it will be evaluated. To prevent this, maybe the
best solution is to use the list function, that return a list with its
arguments.
=>(list 1 2 3)
(1 2 3)
You see the consistency here. As vectors are contructed with vector
function. Notice calling the list function is very different that
using a quote:
=>(list 1 2 (+ 1 2))
(1 2 3)
=>'(1 2 (+ 1 2))
(1 2 (+ 1 2))
This mean that you might not want to use quote everywhere just to say
'here is a list data structure'.
The preference for vectors as data structure when possible is to make
code more lisible. Using a list is just adding more parens, in a
language with lot of parens. Doesn't help the reading.
Using syntaxic sugar for vector, on the contrary help the reading.
On 27 oct, 01:08, e <evier...@gmail.com> wrote:
> not necessarily.
>
> [1 2 3] is a vector that is not evaluated. Since there is no overload with
> things that are, there's no need for a special mark.
>
> '(1 2 3) is currently a way of say, "don't evaluate this list", but it could
> have been:
>
> '(1 2 3) is a list that is not evaluated. No loss of generality. it's a
> special type of list. One that's not evaluated. as opposed to a special
> indicator to the repl.
>
> On Wed, Oct 26, 2011 at 6:09 PM, Mark Rathwell <mark.rathw...@gmail.com>wrote:
>
>
>
>
>
>
>
> > The point to think about here is that functions are also lists, the
> > same as your list of integers. The difference is that one is
> > evaluated, the other is not. That is what the quote is saying: "don't
> > evaluate me". The quote is not actually a part of the list. It's just
> > the way you tell the reader not to evaluate the list that follows.
>
> > So the question is should all unevaluated forms be preceded with a
> > quote in the repl output? To me that would be more confusing.
>
> > On Wed, Oct 26, 2011 at 5:34 PM, e <evier...@gmail.com> wrote:
> > > long long time since I last looked a clojure, but I've never lost
> > > interest and I'm trying to find the time again.
>
> > > for the short version see "*INCONSISTENT*", in the example at the end.
>
> > > I know what the answer will be here. Something like "you will get
> > > used to it". or "it's not important". or "no one hardly uses lists
> > > anymore, anyway, since vectors are not purely contiguous". But, if
> > > you can make things better and it's easy, then why not?
>
> > > So here's the deal:
>
> > > I still think the following is only inconsistent because that's how it
> > > was in older lisps. Specifically, lists had to be quoted so the first
> > > argument wouldn't be called as a function. I asked long ago (here and
> > > in person) why, then regular functions couldn't require the quote so
> > > the paren could be reserved for the list data structure, and Rich
> > > answered that it'd simply be a pain to have to quote every function
> > > call. Well, my mind moves slowly. I'm just now realizing to ask,
> > > "Ok, then how about making the list really be defined using the single
> > > quote as part of it just like sets include the sharp to distinguish
> > > them from maps?". That's a much simpler explanation than saying, "you
> > > have to escape them, etc, etc." I realize this is a small matter since
> > > all I am talking about is how lists are represented as text.
>
> > > checking out the "Try Clojure":
>
> > > if you type the following, you get output that matches what you typed
> > > in every case except for lists.
>
> > > Vectors: --> [1 2 3 4]
> > > [1 2 3 4]
>
> > > Maps: --> {:foo "bar" 3 4}
> > > {:foo "bar" 3 4}
>
> > > Lists: --> '(1 2 3 4)
> > > (1 2 3 4) <----- *INCONSISTENT* why not render this as '(1 2 3 4) ...
> > > this would make much more sense to newbies.
>
> > > Sets: --> #{1 2 3 4}
> > > #{1 2 3 4}
>
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