Hi Guys,
I'm pretty new of clojure so sorry for the maybe stupid question...
Anyway, i'm looking for read a file byte by byte, perfect would be get
a lazy-seq of every byte in the file, it's looks, for me, very weird
that there isn't a built-in or some easy way to do that, but I haven't
find noth
On Sat, 2011-12-10 at 23:13 -0800, Simone Mosciatti wrote:
> Anyway, i'm looking for read a file byte by byte, perfect would be get
> a lazy-seq of every byte in the file, it's looks, for me, very weird
> that there isn't a built-in or some easy way to do that
The tradeoffs aren't universal enough
It's hard to do this efficiently, unfortunately. See my notes & comments on
http://dev.clojure.org/display/design/Byte+Sequences
I did experiment with creating "chunked" binary sequences once, but never
had time to finish it.
-S
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If I do just something like that:
(def fl (clojure.java.io/reader "/path/to/file"))
(defn lazy-reader [fl]
(lazy-seq
(cons (.read fl) (lazy-reader fl
Can work ? (0.03696 ms for 500 char)
Possible problem ?
On Dec 11, 9:49 pm, Stephen Compall wrote:
> On Sat, 2011-12-10 at 23:13
On Mon, 2011-12-12 at 10:21 -0800, Simone Mosciatti wrote:
> (defn lazy-reader [fl]
> (lazy-seq
> (cons (.read fl) (lazy-reader fl
>
> Can work ? (0.03696 ms for 500 char)
> Possible problem ?
You need a termination case; your lazy-reader currently always yields an
infinite sequen
I thought to just put it into a take...
(take number-of-byte-necessary (lazy-reader (clojure.java.io/reader
"path/to/file")))
On Dec 12, 12:34 pm, Stephen Compall
wrote:
> On Mon, 2011-12-12 at 10:21 -0800, Simone Mosciatti wrote:
> > (defn lazy-reader [fl]
> > (lazy-seq
> > (cons (.
Ok, I found a possible problem, if i try to put all together, so write
something like this:
(defn lazy-reader [filename]
(with-open [fl (clojure.java.io/reader filename)]
(loop [bite (.read fl)]
(lazy-seq
(cons (bite) (recur (.read fl)))
Obviously doesn't work...
Any su
On Mon, 2011-12-12 at 20:03 -0800, Simone Mosciatti wrote:
> Any suggest of how fix that ?
In general, avoid loop.
Specifically, try using letfn or (fn SOME-NAME-HERE [args...] ...) as
your recursion target.
--
Stephen Compall
^aCollection allSatisfy: [:each|aCondition]: less is better
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You
You also probably want more efficiency. Try something closer to:
(defn lazy-reader [filename]
(let [rd (fn [rdr]
(let [buf (char-array 4096)
n (.read rdr buf 0 4096)]
(condp == n
-1 (.close rdr)
0 (recur rdr)
Here's a version I hacked up a while ago:
https://gist.github.com/1472163
-S
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No, I'm sure to not use all the sequence, so I will follow your second
advice, but...
Cause of my non-perfect english I've not really understand the last
part.
Who is the caller ?
You suggest something like this:
(let [fl (clojure.java.io/reader "path/filename")
rd (lazy-reader fl)]
(do-m
On Tue, Dec 13, 2011 at 10:14 PM, Simone Mosciatti wrote:
> No, I'm sure to not use all the sequence, so I will follow your second
> advice, but...
>
> Cause of my non-perfect english I've not really understand the last
> part.
> Who is the caller ?
> You suggest something like this:
>
> (let [f
Ok, now by now i think to have understand...
To do right, I should build a macro similar to let where I pass the
filename and after execute the body close the stream, right ?
On Dec 13, 9:42 pm, Cedric Greevey wrote:
> On Tue, Dec 13, 2011 at 10:14 PM, Simone Mosciatti wrote:
> > No, I'm sure t
On Tue, Dec 13, 2011 at 11:12 PM, Simone Mosciatti wrote:
> Ok, now by now i think to have understand...
>
> To do right, I should build a macro similar to let where I pass the
> filename and after execute the body close the stream, right ?
Easier to just use the pre-existing one: with-open.
Som
Where by now:
(defn lazy-reader [fl]
(assert ...)
(lazy-seq
(cons (.read fl) (lazy-reader fl
The first one ?
This means that I haven't understand nothing, right?
(I'm so sorry for this stupid question... :embarassed: )
On Dec 13, 10:23 pm, Cedric Greevey wrote:
> On Tue,
On Tue, Dec 13, 2011 at 11:33 PM, Simone Mosciatti wrote:
> Where by now:
> (defn lazy-reader [fl]
> (assert ...)
> (lazy-seq
> (cons (.read fl) (lazy-reader fl
>
> The first one ?
Er, buffering of the I/O is probably preferable, but that would
probably work OK in many cases.
Thank you so much, just one last thing, why you use a char-array ?
If I want use a byte-array, and no map all the whole sequence ?
On Dec 13, 10:39 pm, Cedric Greevey wrote:
> On Tue, Dec 13, 2011 at 11:33 PM, Simone Mosciatti wrote:
> > Where by now:
> > (defn lazy-reader [fl]
> > (assert .
On Wed, Dec 14, 2011 at 12:04 AM, Simone Mosciatti wrote:
> Thank you so much, just one last thing, why you use a char-array ?
Reader returns chars.
> If I want use a byte-array, and no map all the whole sequence ?
Use an InputStream rather than a reader if you're reading binary files
(or text
Ok thank you so much, i got it.
Thanks again ;-)
Simone
On Dec 14, 3:22 am, Cedric Greevey wrote:
> On Wed, Dec 14, 2011 at 12:04 AM, Simone Mosciatti wrote:
> > Thank you so much, just one last thing, why you use a char-array ?
>
> Reader returns chars.
>
> > If I want use a byte-array, and n
On Wed, Dec 14, 2011 at 11:47 PM, Simone Mosciatti wrote:
> Ok thank you so much, i got it.
>
> Thanks again ;-)
You're welcome.
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