Hi,
On Thursday, September 13, 2012 7:37:09 AM UTC+2, bsmith.occs wrote:
>
>
> Consider a simpler example with a vector, which doesn't produce an
> error since it's allowed to have duplicates:
>
> (def k (atom 0))
> (defn generate-id [] (swap! k inc))
>
> Now when the reader reads this:
>
> [(generate-id) (generate-id)]
>
> It returns a vector containing two lists, each of which contains the
> symbol generate-id.
>
> It's only when this data structure is evaluated, that the functions
> generate-id get called. In some order. I wouldn't rely on getting [1
> 2] and not [2 1].
>
>
you can examine, what the reader returns by using read-string, e.g.
user=> (read-string "[1 2]")
[1 2]
OK
user=> (read-string "[(+ 1 2) 2]")
[(+ 1 2) 2]
Oops?!
user=> (eval (read-string "[(+ 1 2) 2]"))
[3 2]
Aha. :-)
And, of course, the same for maps with gensym:
user=> (read-string "{(gensym) :value}")
{(gensym) :value}
user=> (eval (read-string "{(gensym) :value}"))
{G__333 :value}
Regards,
Stefan
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