Hello,
On Tuesday, March 4, 2014 10:47:12 PM UTC+1, Jason Felice wrote:
>
> Something like
>
> (with-open [rdr (clojure.java.io/reader "/dev/errors-sunday.csv")]
> (->> (line-seq rdr)
> (filter #(re-matches #"..."))
> (map #(nth (string/split % #",") 1))))
>
> Will do what you want. It's laziness to the rescue.
>
Just a heads up: laziness is dangerous when using I/O. In this case,
with-open will close the reader before all lines have been read, and throw
an IOException for trying to read from a closed reader.
Add a `doall` to the end of the threading, and it should be safe. Or use
`slurp` to read the whole file, avoiding the problem to begin with.
As another suggestion: You can use a for comprehension, if you consider it
more readable. It's relatively similar to your imperative version.
(with-open [rdr (clojure.java.io/reader "/dev/errors-sunday.csv")]
(doall
(for [line (line-seq rdr)
:when (re-matches #"^[^,]+,[^,]+,FAIL,.*$" line)]
(second (string/split line #",")))))
-- Jean Niklas
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