Hi,
Am 06.12.2010 um 22:38 schrieb Ken Wesson:
A reduce that discards one of its arguments (e.g. (reduce (fn [n _]
(inc n)) coll)) also strikes me as slightly icky. :)
Indeed this would fit in the 5% left. Anyway: I can't remember writing a
function with accumulator not using the other
What is the difference between rest and next?
This has to do with lazyness. I wrote an answer to that on
stackoverflow.
http://stackoverflow.com/questions/4288476/clojure-rest-vs-next
Should answer everthing.
I'm confused, should I use empty? or not? when to use it?
Why Clojure decided to
On Mon, Dec 6, 2010 at 4:02 AM, nickik nick...@gmail.com wrote:
The easy (and good) solution is to pass the running result onlong the
way. This can be done in diffrent ways.
First the CL Style where you creat a new function in you function that
then does all the work. (from
Ken Wesson)
I didn't expect my question would initiate such a wonderful
discussion, I'm speechless.
Thank you all guys, you are amazing.
Alex, your posts killed in a very good way :)
It was really helpful to morph the code and transform it.
On Dec 6, 11:14 am, Ken Wesson kwess...@gmail.com wrote:
On Mon,
Hi,
Am 06.12.2010 um 10:14 schrieb Ken Wesson:
Then we could use arity functions. (Alex Osborne)
(defn list-length
([coll] (list-length coll 0))
([coll n] (if-let [s (seq coll)]
(recur (rest s) (inc n))
n)))
This is nice style in
On Mon, Dec 6, 2010 at 5:19 AM, Meikel Brandmeyer m...@kotka.de wrote:
Hi,
Am 06.12.2010 um 10:14 schrieb Ken Wesson:
Then we could use arity functions. (Alex Osborne)
(defn list-length
([coll] (list-length coll 0))
([coll n] (if-let [s (seq coll)]
On Dec 6, 11:40 am, Ken Wesson kwess...@gmail.com wrote:
Won't that make the internal recursive call fail though?
And even if not -- ugly IMO. :)
Agree. Why make something slower and more ugly?
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Hi,
Am 06.12.2010 um 11:40 schrieb Ken Wesson:
Won't that make the internal recursive call fail though?
No. Because the metadata is just documentation.
And even if not -- ugly IMO. :)
Tastes vary. I prefer this over a second toplevel function named foo-aux or the
like. I also prefer it
On Dec 5, 9:52 pm, HB hubaghd...@gmail.com wrote:
Hi,
I'm trying to write a function that calculates the length of a list:
(defn list-length [col]
(if col
(+ 1 (list-length(rest col)))
0))
(list-length '(Java, Clojure, Scala))
Upon running it in the REPL, I got the error:
Your function never actually ends because even the empty list
evaluates to true :)
rlm.dna-melting (if (rest '()) true false)
true
rlm.dna-melting (if (next '()) true false)
false
so, changing your list length function to use next will work
rlm.dna-melting (defn list-length [col] (if col (+ 1
On Sun, Dec 5, 2010 at 5:16 PM, Robert McIntyre r...@mit.edu wrote:
Your function never actually ends because even the empty list
evaluates to true :)
rlm.dna-melting (if (rest '()) true false)
true
rlm.dna-melting (if (next '()) true false)
false
so, changing your list length function
What is the difference between rest and next?
I'm confused, should I use empty? or not? when to use it?
Robert,
Your code is working but if I use empty? , it returns 0 instead of the
actual count.
Why?
Why Clojure decided to handle an empty list as a not false? this is a
big (if not) departure
HB hubaghd...@gmail.com writes:
I'm trying to write a function that calculates the length of a list:
(defn list-length [col]
(if col
(+ 1 (list-length(rest col)))
0))
(list-length '(Java, Clojure, Scala))
Upon running it in the REPL, I got the error:
In Clojure, empty sequences are not considered logically false, so
your code continues going after reducing col to an empty list. You
need to explicitly check whether the collection is empty, like so:
(defn list-length [col]
(if (empty? col)
0
(+ 1 (list-length (rest col)
Cheers,
OMG, this is too much Clojure code for me to handle O.o
Alex, you just killed me :)
Do you previous Lisp knowledge? or Clojure is your first Lisp? you are
so good.
I will spend the next couple of hours studying it.
Thanks all, you are awesome.
On Dec 6, 12:47 am, Alex Osborne a...@meshy.org
Ken Alex,
Why you aren't calling empty? when you want to check if a collection
is empty?
Isn't (if s) supposed to return true if s is empty ?
On Dec 6, 12:27 am, Ken Wesson kwess...@gmail.com wrote:
On Sun, Dec 5, 2010 at 5:16 PM, Robert McIntyre r...@mit.edu wrote:
Your function never
On Sun, Dec 5, 2010 at 6:55 PM, HB hubaghd...@gmail.com wrote:
Ken Alex,
Why you aren't calling empty? when you want to check if a collection
is empty?
Isn't (if s) supposed to return true if s is empty ?
If coll is empty, (seq coll) and (next coll) are both nil, which is
logical false.
--
HB hubaghd...@gmail.com writes:
OMG, this is too much Clojure code for me to handle O.o
Alex, you just killed me :)
Hehe, sorry. Just thought it might be helpful to show the progression
of dealing with all the little edge cases.
It perhaps looks much more fiddly, but you're doing more there
HB hubaghd...@gmail.com writes:
Ken Alex,
Why you aren't calling empty? when you want to check if a collection
is empty?
Here's the definition of empty? from clojure/core.clj:
(defn empty?
Returns true if coll has no items - same as (not (seq coll)).
Please use the idiom
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