Comments on: Clojure: A first look at recursive functions http://www.markhneedham.com/blog/2009/11/17/clojure-a-first-look-at-recursive-functions/ Thoughts on Software Development Tue, 09 Mar 2010 23:57:49 +0000 http://wordpress.org/?v=2.8.4 hourly 1 By: Tweets that mention Clojure: A first look at recursive functions at Mark Needham -- Topsy.com http://www.markhneedham.com/blog/2009/11/17/clojure-a-first-look-at-recursive-functions/comment-page-1/#comment-26896 Tweets that mention Clojure: A first look at recursive functions at Mark Needham -- Topsy.com Wed, 18 Nov 2009 09:48:15 +0000 http://www.markhneedham.com/blog/?p=1836#comment-26896 [...] This post was mentioned on Twitter by Mark Needham, ajlopez. ajlopez said: RT @markhneedham: first thoughts on clojure recur - http://bit.ly/3O2lRZ [...] [...] This post was mentioned on Twitter by Mark Needham, ajlopez. ajlopez said: RT @markhneedham: first thoughts on clojure recur – http://bit.ly/3O2lRZ [...]

]]> By: Mark Needham http://www.markhneedham.com/blog/2009/11/17/clojure-a-first-look-at-recursive-functions/comment-page-1/#comment-26862 Mark Needham Tue, 17 Nov 2009 14:09:51 +0000 http://www.markhneedham.com/blog/?p=1836#comment-26862 Thanks, I didn't know about defn not being defined in the local scope so I won't be doing that anymore! Thanks, I didn't know about defn not being defined in the local scope so I won't be doing that anymore!

]]> By: James Sofra http://www.markhneedham.com/blog/2009/11/17/clojure-a-first-look-at-recursive-functions/comment-page-1/#comment-26844 James Sofra Tue, 17 Nov 2009 02:49:33 +0000 http://www.markhneedham.com/blog/?p=1836#comment-26844 Your last example using the arity overload is actually the most idiomatic. Nesting a named function using defn is not idiomatic at all and is discouraged since it is not really defined in the local scope as you may expect, you could use letfn to achieve the same thing. Otherwise you could also use loop as a recur target which works quite nicely, so it may look like this: (defn count-down [from] (loop [so-far [] down-from from] (if (zero? down-from) so-far (recur (conj so-far down-from) (dec down-from))))) Cheers, James Your last example using the arity overload is actually the most idiomatic. Nesting a named function using defn is not idiomatic at all and is discouraged since it is not really defined in the local scope as you may expect, you could use letfn to achieve the same thing. Otherwise you could also use loop as a recur target which works quite nicely, so it may look like this:

(defn count-down [from]
(loop [so-far [] down-from from]
(if (zero? down-from)
so-far
(recur (conj so-far down-from) (dec down-from)))))

Cheers,
James

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