On Oct 26, 2011, at 7:08 PM, e wrote:
> [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.
If you type [1 2 3] into the REPL it is evaluated. The E part of the REPL
always runs. Some expressions evaluate to themselves. In this case each number
evaluates to itself and the vector evaluates to itself:
user> [1 2 3]
[1 2 3]
If you have an expression as one of the items in the vector, it will be
evaluated:
user> [1 (+ 1 1) 3]
[1 2 3]
Putting a quote out front suppresses all evaluation:
user> '[1 (+ 1 1) 3]
[1 (+ 1 1) 3]
> '(1 2 3) is currently a way of say, "don't evaluate this list",
More completely it says, "don't evaluate the entire expression that follows
including any and all sub-expressions"
> 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.
Current behavior:
user> '(1 (+ 1 1) 3)
(1 (+ 1 1) 3)
The behavior you propose:
user> '(1 (+ 1 1) 3)
(1 2 3)
Currently 'x is equivalent to (quote x) for all values of x. With the syntax
you propose that's no longer true.
clojure.main/repl allows you to replace the evaluator with any function of one
argument. If you bring up a repl with, say, lein repl, you can start a nested
repl with identity as the evaluator and see how things are read (which can be
interesting):
% lein repl
REPL started; server listening on localhost port 46512
user=> (clojure.main/repl :eval identity)
user=> (+ 1 2)
(+ 1 2)
user=> '(+ 1 2)
(quote (+ 1 2))
user=> [1 2 3]
[1 2 3]
user=> [1 (+ 1 1) 3]
[1 (+ 1 1) 3]
user=> 'x
(quote x)
user=> x
x
user=> '[1 (+ 1 1) 3]
(quote [1 (+ 1 1) 3])
user=> #(+ 3 %)
(fn* [p1__161#] (+ 3 p1__161#))
--Steve
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