That makes sense. Thanks for the quick help!
On Jul 14, 2:40 pm, Chouser <chou...@gmail.com> wrote:
> On Tue, Jul 14, 2009 at 3:04 PM, bgray<graybran...@gmail.com> wrote:
>
> > I'm not sure if this is a binding issue or not.
>
> > user=> (def a 1)
> > #'user/a
> > user=> (binding [a 3] (filter #(= % a) '(1 2 3)))
> > (1)
> > user=>
>
> > In this case, I was expecting a list with 3 in it.
>
> filter is lazy, and your lazy seq is "leaking" out of the
> binding dynamic scope. You must be careful with 'binding'
> in the presence of delayed evaluation and threads. This
> includes lazy-seqs, delays, futures, agents, and really
> closures in general.
>
> To get your expected result, simply force the seq to be
> realized before you return it, such as with doall, or put it
> into a non-lazy collection, such as with vec.
>
> user=> (binding [a 3] (doall (filter #(= % a) '(1 2 3))))
> (3)
>
> --Chouser
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