Hi,
your comparison is not fair. The map example merely assoc's a new value,
while in the record case you create a complete fresh value with a different
type. Here some more comparisons:
user=> (defrecord Foo [a b])
user.Foo
user=> (defrecord Bar [a b c])
user.Bar
user=> (let [x (->Foo 10 20)]
On Wed, Apr 25, 2012 at 10:30 AM, Shantanu Kumar
wrote:
> user=> (let [x (Foo. 10 20)] (time (Bar. (:a x) (:b x) 30)))
> "Elapsed time: 0.686 msecs"
> #user.Bar{:a 10, :b 20, :c 30}
>
> Whereas, doing the same with a map is very cheap:
>
> user=> (let [x {:a 10 :b 20}] (time (assoc x :c 30)))
> "E
> user=> (map->B (merge (A. 1 2) {:c 1}))
> #user.B{:a 1, :b 2, :c 1}
Pretty cool – thanks! Didn't know about map->
Shantanu
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On Wed, Apr 25, 2012 at 10:30 PM, Shantanu Kumar
wrote:
> 2. It is quite verbose to construct a Bar from a Foo. Knowing that
> there is an overlap of attributes, is there a less verbose way to do
> it?
>
>
Have you tried this?
user=> (map->B (merge (A. 1 2) {:c 1}))
#user.B{:a 1, :b 2, :c 1}
Tha
Hi,
I have a scenario where I have two records:
(defrecord Foo [a b])
(defrecord Bar [a b c])
You will notice Bar has only an attribute more than Foo. Both Foo and
Bar are data abstractions where Foo is a subset of Bar.
Now, when I try to construct a Bar from an existing Foo instance, I
get thi
