The filter documentation reads:
"Returns a lazy sequence of the items in coll for which (pred item)
returns true. pred must be free of side-effects."
So that means I should not write a function like this:
(defn unique [sc]
"Returns a lazy sequence with all consecutive duplicates removed"
(let [last (atom (Object.))]
(filter #(let [ok (not= @last %)] (reset! last %) ok) sc)))
user=> (unique [1 2 3 3 4 5 5 6])
(1 2 3 4 5 6)
But in contrast to functions that can be retried (compare-and-swap
etc.), I don't immediately see why having side effects in filter would
be bad. Can anybody enlighten me? And how should I do this instead?
Thanks
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
