Hey,
for produces a lazy sequence (as does flatten) which is hurting you here.
You could wrap everything in a doall but I'd recommend using reduce since
thats technically what you want here. I'd probably go for something like:
(defn filter-file [filename]
(with-open [rdr (io/reader filename)]
(reduce (fn [words line]
(->> (str/split line #"\s+")
(filter #(and (<= (count %) 9)
(>= (count %) 4)))
(set)
(set/union words)))
#{}
(line-seq rdr))))
Wether you want a set or a vector is up to you, set seems more logical to
me here. Didn't check how expensive set/union is, might be better to use
concat with a final set (after reduce) if there are a lot of lines.
Anyways, use reduce. ;)
HTH,
/thomas
On Saturday, June 8, 2013 6:53:05 AM UTC+2, Steven Arnold wrote:
>
> Hi, I am trying to write a function to extract words from a file that are
> four characters or more, and nine characters or less. Many words could
> appear on a single line, so the implementation needs to combine the words
> from all the lines. I wrote a function to do this, but I am getting an
> error that the stream is closed.
>
> The function and error are below. The idea is that we iterate over the
> lines in the file, splitting each line on whitespace and selecting those
> that meet the length requirements, giving us a list of lists, which is then
> flattened into a single list.
>
> Most examples online of 'with-open' use it in conjunction with 'doseq',
> but I don't think doseq returns the value of expressions like for does.
>
> As a Clojure newb, I'd welcome any feedback, but in particular I'm
> interested in what's going on with the closed stream. Any thoughts?
>
> (defn filter-file
> []
> (with-open [rdr (reader "/Users/thoth/wordlist.txt")]
> (flatten
> (for
> [line (line-seq rdr)]
> (filter
> (and #(<= (count %) 9)
> #(>= (count %) 4))
> (split line #"\s+"))))))
>
> The error is below. The 'ha-ha' and 'splenetic' are the first couple
> words in the wordlist. In case you're wondering, they come from
> dictionary.com's previous words of the day.
>
> [ 09:39 PM (6) theorem:thoth ~/Source/clojure/test ] > lein run
> (ha-ha splenetic Exception in thread "main" java.io.IOException: Stream
> closed
> [...lengthy traceback omitted, but the "for" line seems to be the one that
> triggers the error]
>
> Thanks in advance!
> steven
>
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