On May 28, 2009, at 12:35 AM, Mikio Hokari wrote:
>
>>> I wonder if there is a more idiomatic way to compare two lazy
>>> sequences... lazily?
>
> You can just use =.
I guess I'm imagining a group-by like Haskell's, which takes an
equality comparison function and just returns a list of lists. Which
would look like this:
(defn span [f coll]
(if (empty? coll)
['() '()]
(if (f (first coll))
(let [[more & rest] (span f rest)]
[(cons (first coll) more) rest])
['() coll])))
(defn group-by [f [x & xs :as coll]]
(if (empty? coll)
'()
(let [[ys zs] (span #(f x %) xs)]
(cons (cons x ys) (lazy-seq (group-by f zs))))))
Now you ought to be able to do this with = on a sorted list as I
described in the huge message I sent a bit ago. (remove #(= (length %)
1) (group-by = (sort ...))). Sorting is still the question for me
though.
—
Daniel Lyons
http://www.storytotell.org -- Tell It!
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