On Wed, Jan 4, 2012 at 07:36, Johnny Weng Luu <johnny.weng....@gmail.com> wrote:
> One thing that seems weird is the way Clojure destructures a map
>
> I have this map: {:last-name "Vinge" :first-name "Vernor"} which is passed
> to this function: (defn greet-author-2 [{fname :first-name}] ... )
>
> Wouldn't it be better doing: (defn greet-author-2 [{:first-name fname}] ...
> )
>
> You first type the keyword, then followed by the parameter to bind to. It
> reads that the value is bound to the parameter in the same place.
>
> Feels more natural to me in a way.
>
> Thoughts?
Doesn't make sense that way around. Remember that in a map, the key is
unique, but the value need not be. Remember that in a Lisp this isn't
just a question of arbitrary syntax. The code you write is always also
a data structure.
With the current solution I can write this, which while not obviously
useful at least has an obvious meaning:
(let [{name1 :name name2 :name} {:name "a"}]
(= name1 name2))
Your proposal would seem to allow this:
(let [{:first-name name :last-name name} {:last-name "last"
:first-name "first"}]
(= name ???))
It's not clear what this would mean.
It would also make it impossible to bind the value for a given key to
more than one variable, since map keys must be unique:
(let [{:name name1 :name name2} {:name "a"}]
;; boom? )
// Ben
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