For one, the type of a record is not as malleable as the other attributes of
the record. It's less dynamic.
2011/2/18 Base <basselh...@gmail.com>
> Thank you Stuart! This makes perfect sense and is quite elegant.
>
> So is performance the only compelling reason to do this? I am assuming
> there are times that maps are 'good enough', but would you say that if
> you ever have a defined data structure you would advise to use
> defrecord to gain this increase in speed? Are there some things that
> you can do with maps that you cannot do with defrecord?
>
> On Feb 18, 3:05 pm, Stuart Sierra <the.stuart.sie...@gmail.com> wrote:
> > Hi Base,
> >
> > It's easy, because instances of defrecord behave identically to maps.
> Say
> > you have a lot of "person" records that look like this:
> >
> > {:first-name "Stuart", :last-name "Sierra", :location "NYC"}
> >
> > You might write a constructor function to create these maps:
> >
> > (defn person [& options]
> > (apply hash-map options))
> >
> > You use the `person` function to create "person" maps, and you manipulate
> > them using Clojure's map functions (assoc, dissoc, get, etc.). You can
> > easily add or remove keys in the map as you develop your application.
> >
> > Then you want "person" records to be smaller and faster. So you write:
> >
> > (defrecord Person [first-name last-name location])
> >
> > (defn person [& options]
> > (let [{:keys [first-name last-name location]} options]
> > (Person. first-name last-name location)))
> >
> > Poof! None of your existing code has to change how it creates and
> > manipulates "person"s, but all your maps are now records.
> >
> > -Stuart Sierra
> > clojure.com
>
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