On Sep 20, 7:02 am, Chouser <chou...@gmail.com> wrote:
> On Mon, Sep 19, 2011 at 2:20 PM, qhfgva <qhf...@gmail.com> wrote:
> > I'm working through some puzzle problems to help get up to speed on
> > clojure. Generally I've been able to pound on something for a while
> > and get the moment of enlightenment but for some reason this seemingly
> > simple item is stumping me. (FWIW, the puzzle in question is the
> > crossing a bridge at night in pairs with one lantern problem).
>
> > Here is The output that is confusing me:
>
> > Using:
>
> > (defn not-seen-already? [states state]
> > (not (some #{state} states)))
>
> > user=> path
> > [{:left [1 2 3], :lamp :left, :right []} {:lamp :right, :left (2
> > 3), :right (1)}]
> > user=> next-steps
> > ({:lamp :left, :right (), :left (1 2 3)})
> > user=> next-steps2
> > [{:lamp :left, :right [], :left [1 2 3]}]
> > user=> (filter #(not-seen-already? path %) next-steps)
> > ({:lamp :left, :right (), :left (1 2 3)})
> > user=> (filter #(not-seen-already? path %) next-steps2)
> > ()
> > user=> (filter #(not-seen-already? path %) '({:lamp :left, :right
> > (), :left (1 2 3)}))
> > ()
> > user=> (filter #(not-seen-already? path %) [{:lamp :left, :right
> > [], :left [1 2 3]}])
> > ()
>
> > As you can see above, passing in the variable next-steps and next-
> > steps2 above into my expression I get two different results (I was
> > expecting the second result). When I pass the data structures in
> > explicitly I get the same result for each.
>
> I can't reproduce your results:
>
> user=> (filter #(not-seen-already? path %) next-steps)
> ()
>
> What does your REPL say if you: (= (first next-steps) (first path))
> What version of Clojure are you using?
>
> --Chouser
Thanks for your response. Here you go: (with extra info as well)
user=> (first path)
(first path)
{:left [1 2 3], :lamp :left, :right []}
user=> (first next-steps)
(first next-steps)
{:lamp :left, :right (), :left (1 2 3)}
user=> (first next-steps2)
(first next-steps2)
{:lamp :left, :right [], :left [1 2 3]}
user=> (class path)
(class path)
clojure.lang.PersistentVector
user=> (class next-steps)
(class next-steps)
clojure.lang.LazySeq
user=> (class next-steps2)
(class next-steps2)
clojure.lang.PersistentVector
user=> (first path)
(first path)
{:left [1 2 3], :lamp :left, :right []}
user=> (first next-steps)
(first next-steps)
{:lamp :left, :right (), :left (1 2 3)}
user=> (first next-steps2)
(first next-steps2)
{:lamp :left, :right [], :left [1 2 3]}
user=> (filter #(not-seen-already? path %) next-steps)
(filter #(not-seen-already? path %) next-steps)
({:lamp :left, :right (), :left (1 2 3)})
user=> (= (first next-steps) (first path))
(= (first next-steps) (first path))
true
user=> *clojure-version*
*clojure-version*
{:interim true, :major 1, :minor 2, :incremental 0, :qualifier
"master"}
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