Chris and Chris
Thanks
On Wed, Jan 7, 2009 at 9:09 AM, Christophe Grand <christo...@cgrand.net>wrote:
>
> janus a écrit :
> > It can't figure out why this is not working or was I sleeping while
> > trying it out.
> >
> > (apply #(println %) [2 3])
> >
> This line is equivalent to (#(println %) 2 3) which errors since
> #(println %) takes only one argument.
> user=> (macroexpand '#(println %))
> (fn* [p1__3493] (println p1__3493))
>
> Depending on what you were trying to achieve, you could have written:
> (apply println [2 3]) ; same as (println 2 3)
> (apply #(println %) [2 3] nil) ; same as (#(println %) [2 3]) or
> (println [2 3])
> (map #(println %) [2 3]) ; roughly equivalent to [(#(println %) 2)
> (#(println %) 3)] or [(println 2) (println 3)]
> (map println [2 3]) ; roughly equivalent to [(println 2) (println 3)]
> (doseq [i [2 3]] (print i)) ; same as (do (println 2) (println 3))
>
> > And, why is it that I can't do this?
> >
> > Instead of (let [{coin :coin :as snake}{...................}][coin
> > snake])
> > I tried this (let [{:coin coin :as snake}{...................}][coin
> > snake]) and got failure. Why is it so?(just changed the position of
> > the key :coin)
> >
> See http://clojure.org/special_forms#toc4 "Map binding-forms [...]
> consists of a map of binding-form-key pairs."
> coin :coin is a binding-form-key pair while :coin coin is
> key-binding-form pair.
> Some pairs start with a keyword (:as, :or, :keys, :strs and :syms) but
> they have a special meaning.
>
> Hope this helps.
>
> Christophe
>
> >
>
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