Re: update a ref struct
I know you are asking about refs, but you might want to think about using reduce to walk the line-seq. the nature of reduce lets you have access to the line-seq, two lines at a time no need for a ref. On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle <[EMAIL PROTECTED]> wrote: > I am parsing a file and to compare the current line > with the previous line of the file. I am using line-seq > to go thru the file and I thought I would create a > ref to store the previous line. When I want to update > the previous line value I can't seem to do it. I've > never used refs before so I'm sure I'm doing something > very stupid. > > (defstruct line :lat :lon :name) > > (defn convert [file] > (let [prev-line (ref (struct line))] > (with-open [r (reader file)] >(doseq [l (line-seq r)] > (let [ps (split #"," l) > c-line (struct line (ps 0) (ps 1) (ps 2))] >(if (not= c-line @pre-line) > (do ; do stuff here then update pre-line > (dosync ref-set pre-line (apply struct line (vals c-line))) > (println @pre-line ; this prints out all nils > doesn't seem to work > > > > Sorry if this email is not formatted correctly. Something is wrong with my > browser > currently typing in a textarea. Thanks. > > > > > > -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
Thanks Kevin, I will try using reduce instead. I would like to know what I'm doing wrong with updating the ref for future reference. Thanks. On Mon, Nov 24, 2008 at 3:23 PM, Kevin Downey <[EMAIL PROTECTED]> wrote: > > I know you are asking about refs, but you might want to think about > using reduce to walk the line-seq. the nature of reduce lets you have > access to the line-seq, two lines at a time no need for a ref. > > On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle <[EMAIL PROTECTED]> > wrote: > > I am parsing a file and to compare the current line > > with the previous line of the file. I am using line-seq > > to go thru the file and I thought I would create a > > ref to store the previous line. When I want to update > > the previous line value I can't seem to do it. I've > > never used refs before so I'm sure I'm doing something > > very stupid. > > > > (defstruct line :lat :lon :name) > > > > (defn convert [file] > > (let [prev-line (ref (struct line))] > > (with-open [r (reader file)] > >(doseq [l (line-seq r)] > > (let [ps (split #"," l) > > c-line (struct line (ps 0) (ps 1) (ps 2))] > >(if (not= c-line @pre-line) > > (do ; do stuff here then update pre-line > > (dosync ref-set pre-line (apply struct line (vals > c-line))) > > (println @pre-line ; this prints out all nils > > doesn't seem to work > > > > > > > > Sorry if this email is not formatted correctly. Something is wrong with > my > > browser > > currently typing in a textarea. Thanks. > > > > > > > > > > > > > > > -- > The Mafia way is that we pursue larger goals under the guise of > personal relationships. >Fisheye > > > > --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
On Mon, Nov 24, 2008 at 5:17 PM, Brian Doyle <[EMAIL PROTECTED]> wrote: > I am parsing a file and to compare the current line > with the previous line of the file. I am using line-seq > to go thru the file and I thought I would create a > ref to store the previous line. When I want to update > the previous line value I can't seem to do it. I've > never used refs before so I'm sure I'm doing something > very stupid. > > (defstruct line :lat :lon :name) > > (defn convert [file] > (let [prev-line (ref (struct line))] > (with-open [r (reader file)] >(doseq [l (line-seq r)] > (let [ps (split #"," l) > c-line (struct line (ps 0) (ps 1) (ps 2))] >(if (not= c-line @pre-line) > (do ; do stuff here then update pre-line > (dosync ref-set pre-line (apply struct line (vals c-line))) > (println @pre-line ; this prints out all nils > doesn't seem to work > > Your let binds prev-line, while the code inside uses pre-line. Is that just a typo in your email, or is that the code you're running, too? Shawn --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
ref-set needs its one set of parens, and the last thing in the ref-set call needs to be a function either (fn [x] ...) or a symbol for a var that holds a function On Mon, Nov 24, 2008 at 2:30 PM, Brian Doyle <[EMAIL PROTECTED]> wrote: > Thanks Kevin, I will try using reduce instead. I would like to know what > I'm doing wrong with updating the ref for future reference. Thanks. > > On Mon, Nov 24, 2008 at 3:23 PM, Kevin Downey <[EMAIL PROTECTED]> wrote: >> >> I know you are asking about refs, but you might want to think about >> using reduce to walk the line-seq. the nature of reduce lets you have >> access to the line-seq, two lines at a time no need for a ref. >> >> On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle <[EMAIL PROTECTED]> >> wrote: >> > I am parsing a file and to compare the current line >> > with the previous line of the file. I am using line-seq >> > to go thru the file and I thought I would create a >> > ref to store the previous line. When I want to update >> > the previous line value I can't seem to do it. I've >> > never used refs before so I'm sure I'm doing something >> > very stupid. >> > >> > (defstruct line :lat :lon :name) >> > >> > (defn convert [file] >> > (let [prev-line (ref (struct line))] >> > (with-open [r (reader file)] >> >(doseq [l (line-seq r)] >> > (let [ps (split #"," l) >> > c-line (struct line (ps 0) (ps 1) (ps 2))] >> >(if (not= c-line @pre-line) >> > (do ; do stuff here then update pre-line >> > (dosync ref-set pre-line (apply struct line (vals >> > c-line))) >> > (println @pre-line ; this prints out all nils >> > doesn't seem to work >> > >> > >> > >> > Sorry if this email is not formatted correctly. Something is wrong with >> > my >> > browser >> > currently typing in a textarea. Thanks. >> > >> > >> > >> > > >> > >> >> >> >> -- >> The Mafia way is that we pursue larger goals under the guise of >> personal relationships. >>Fisheye >> >> > > > > > -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
For using references in general, here is a little example: [EMAIL PROTECTED]:~$ clj Clojure user=> (def foo (ref 0)) #'user/foo user=> foo # user=> @foo 0 user=> (ref-set foo 1) java.lang.IllegalStateException: No transaction running (NO_SOURCE_FILE:0) user=> (dosync (ref-set foo 1)) 1 user=> @foo 1 user=> Notice that you have to wrap ref-set in a transaction using dosync, and reading the reference requires the @ macro. -Jeff Brian Doyle wrote: > I am parsing a file and to compare the current line > with the previous line of the file. I am using line-seq > to go thru the file and I thought I would create a > ref to store the previous line. When I want to update > the previous line value I can't seem to do it. I've > never used refs before so I'm sure I'm doing something > very stupid. > > (defstruct line :lat :lon :name) > > (defn convert [file] > (let [prev-line (ref (struct line))] > (with-open [r (reader file)] >(doseq [l (line-seq r)] > (let [ps (split #"," l) > c-line (struct line (ps 0) (ps 1) (ps 2))] >(if (not= c-line @pre-line) > (do ; do stuff here then update pre-line > (dosync ref-set pre-line (apply struct line (vals c-line))) > (println @pre-line ; this prints out all nils > doesn't seem to work > > > > Sorry if this email is not formatted correctly. Something is wrong with > my browser > currently typing in a textarea. 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
On Mon, Nov 24, 2008 at 2:34 PM, Kevin Downey <[EMAIL PROTECTED]> wrote: > ref-set needs its one set of parens, and the last thing in the ref-set > call needs to be a function either (fn [x] ...) or a symbol for a var > that holds a function I made a mistake here. I was thinking of alter, not ref-set. > On Mon, Nov 24, 2008 at 2:30 PM, Brian Doyle <[EMAIL PROTECTED]> wrote: >> Thanks Kevin, I will try using reduce instead. I would like to know what >> I'm doing wrong with updating the ref for future reference. Thanks. >> >> On Mon, Nov 24, 2008 at 3:23 PM, Kevin Downey <[EMAIL PROTECTED]> wrote: >>> >>> I know you are asking about refs, but you might want to think about >>> using reduce to walk the line-seq. the nature of reduce lets you have >>> access to the line-seq, two lines at a time no need for a ref. >>> >>> On Mon, Nov 24, 2008 at 2:17 PM, Brian Doyle <[EMAIL PROTECTED]> >>> wrote: >>> > I am parsing a file and to compare the current line >>> > with the previous line of the file. I am using line-seq >>> > to go thru the file and I thought I would create a >>> > ref to store the previous line. When I want to update >>> > the previous line value I can't seem to do it. I've >>> > never used refs before so I'm sure I'm doing something >>> > very stupid. >>> > >>> > (defstruct line :lat :lon :name) >>> > >>> > (defn convert [file] >>> > (let [prev-line (ref (struct line))] >>> > (with-open [r (reader file)] >>> >(doseq [l (line-seq r)] >>> > (let [ps (split #"," l) >>> > c-line (struct line (ps 0) (ps 1) (ps 2))] >>> >(if (not= c-line @pre-line) >>> > (do ; do stuff here then update pre-line >>> > (dosync ref-set pre-line (apply struct line (vals >>> > c-line))) >>> > (println @pre-line ; this prints out all nils >>> > doesn't seem to work >>> > >>> > >>> > >>> > Sorry if this email is not formatted correctly. Something is wrong with >>> > my >>> > browser >>> > currently typing in a textarea. Thanks. >>> > >>> > >>> > >>> > > >>> > >>> >>> >>> >>> -- >>> The Mafia way is that we pursue larger goals under the guise of >>> personal relationships. >>>Fisheye >>> >>> >> >> >> >> >> > > > > -- > The Mafia way is that we pursue larger goals under the guise of > personal relationships. >Fisheye > -- The Mafia way is that we pursue larger goals under the guise of personal relationships. Fisheye --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
Another possible approach. Key idea here is to use partition to create a sliding window over the lines, plus a sentinel value (I picked "") before the first line. Pretty sure I like partition over reduce for this particular example. (ns examples.convert (:use [clojure.contrib.duck-streams :only (reader)]) (:use [clojure.contrib.str-utils :only (re-split)])) (defstruct line :lat :lon :name) (defn convert [file] (with-open [r (reader file)] (doseq [[l1 l2] (partition 2 1 (cons "" (line-seq r)))] (if (not= l1 l2) (println (apply struct line (re-split #"," l2))) > I am parsing a file and to compare the current line > with the previous line of the file. I am using line-seq > to go thru the file and I thought I would create a > ref to store the previous line. When I want to update > the previous line value I can't seem to do it. I've > never used refs before so I'm sure I'm doing something > very stupid. > > (defstruct line :lat :lon :name) > > (defn convert [file] > (let [prev-line (ref (struct line))] > (with-open [r (reader file)] >(doseq [l (line-seq r)] > (let [ps (split #"," l) > c-line (struct line (ps 0) (ps 1) (ps 2))] >(if (not= c-line @pre-line) > (do ; do stuff here then update pre-line > (dosync ref-set pre-line (apply struct line (vals c- > line))) > (println @pre-line ; this prints out all > nils doesn't seem to work > > > > Sorry if this email is not formatted correctly. Something is wrong > with my browser > currently typing in a textarea. 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
Re: update a ref struct
Yep, that's just a typo in the email. Something was wrong with my browser and I couldn't just paste the code in :( On Mon, Nov 24, 2008 at 3:33 PM, Shawn Hoover <[EMAIL PROTECTED]>wrote: > On Mon, Nov 24, 2008 at 5:17 PM, Brian Doyle <[EMAIL PROTECTED]>wrote: > >> I am parsing a file and to compare the current line >> with the previous line of the file. I am using line-seq >> to go thru the file and I thought I would create a >> ref to store the previous line. When I want to update >> the previous line value I can't seem to do it. I've >> never used refs before so I'm sure I'm doing something >> very stupid. >> >> (defstruct line :lat :lon :name) >> >> (defn convert [file] >> (let [prev-line (ref (struct line))] >> (with-open [r (reader file)] >>(doseq [l (line-seq r)] >> (let [ps (split #"," l) >> c-line (struct line (ps 0) (ps 1) (ps 2))] >>(if (not= c-line @pre-line) >> (do ; do stuff here then update pre-line >> (dosync ref-set pre-line (apply struct line (vals >> c-line))) >> (println @pre-line ; this prints out all nils >> doesn't seem to work >> >> > Your let binds prev-line, while the code inside uses pre-line. Is that just > a typo in your email, or is that the code you're running, too? > > Shawn > > > > > --~--~-~--~~~---~--~~ 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 To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~--~~~~--~~--~--~---
