Error installing iconv

Today I was trying to install the iconv gem, and was getting this error

$gem install iconv
Building native extensions.  This could take a while...
ERROR:  Error installing iconv:
	ERROR: Failed to build gem native extension.

        <rvm_dir>/rubies/ruby-2.0.0-preview2/bin/ruby extconf.rb
checking for rb_enc_get() in ruby/encoding.h... yes
checking for iconv() in iconv.h... no
checking for iconv() in -liconv... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=<rvm_dir>/rubies/ruby-2.0.0-preview2/bin/ruby
	--with-iconv-dir
	--with-iconv-include
	--without-iconv-include=${iconv-dir}/include
	--with-iconv-lib
	--without-iconv-lib=${iconv-dir}/
	--enable-config-charset
	--disable-config-charset
	--with-config-charset
	--without-config-charset
	--with-iconvlib
	--without-iconvlib


Gem files will remain installed in <rvm_dir>/gems/ruby-2.0.0-preview2/gems/iconv-1.0.2 for inspection.
Results logged to <rvm_dir>/gems/ruby-2.0.0-preview2/gems/iconv-1.0.2/ext/iconv/gem_make.out

After a bit of searching, I found a number of answers suggesting that I would need to reinstall ruby via RVM, but in the following StackOverflow question
failed-to-build-iconv-gem-on-ruby-1-9-2.

In it was the solution:
gem install iconv -- --with-iconv-dir=/usr/local/Cellar/libiconv/1.13.1

After that, all was well.

–Proctor

Log File parsing with Futures in Clojure

As the follow up to my post Running Clojure shell scripts in *nix enviornments, here is how I implemented an example using futures to parse lines read in from standard in as if the input was piped from a tail and writing out the result of parsing the line to standard out.

First due to wanting to run this a script from the command line I add this a the first line of the script:

 
!/usr/bin/env lein exec

As well, I will also be wanting to use the join function from the clojure.string namespace.

 
(use '[clojure.string  nly (join)])

When dealing with futures I knew I would need an agent to adapt standard out.

(def out (agent *out*))

I also wanted to separate each line by a new line so I created a function writeln. The function takes a Java Writer and calls write and flush on each line passed in to the function:

(defn writeln [^java.io.Writer w line]
  (doto w
    (.write (str line "\n"))
    .flush))

Next I have my function to analyze the line, as well as sending the result of that function to the agent via the send-off function.

(defn analyze-line [line]
  (str line "   " (join "  " (map #(join ":" %) (sort-by val > (frequencies line))))))

(defn process-line [line]
  (send-off out writeln (analyze-line line)))

The analyze-line function is just some sample code to return a string of the line and the frequencies of each character in the line passed in. The process-line function takes a line and calls send-off to the agent out for the function writeln with the results of calling the function analyze-line.

With all of these functions defined I now need to just loop continuously and process lines that are not empty, and call process-line for each line as a future.

(loop []
  (let [line (read-line)]
    (when line
      (future (process-line line)))
      (recur)))

Running Clojure shell scripts in *nix environments

I was recently trying to create a basic piece of Clojure code to play with “real-time” log file parsing by playing with futures. The longer term goal of the experiment is to be able to tail -f a log file pipe that into my Clojure log parser as input.

As I wasn’t sure exactly what I would need to be doing, I wanted an easy way to run some code quickly without having to rebuild the jars through Leiningen every time I wanted to try something, in a manner similar to the way I am thinking I will be using it if the experiment succeeds.

I created a file test_input with the following lines:

1 hello
2 test
3 abacus
4 qwerty
5 what
6 dvorak

With this in place, my goal was to be able to run something like cat test_file | parser_concept. After a bit of searching I found the lein-exec plugin for Leiningen, and after very minor setup I was able to start iterating with input piped in from elsewhere.

The first step was to open my profiles.clj file in my ~/.lein directory. I made sure lein-exec was specified in my user plugins as so:

{:user {:plugins [[lein-exec "0.2.1"]
                  ;other plugins for lein
                 ]}}

With this in place I just put the following line at the top of my script.clj file:

#!/usr/bin/env lein exec

I then changed the permissions of script.clj file to make it executable, I was able to run the following and have my code run against the input.

cat test_input | ./script.clj

I will be posting a follow up entry outlining my next step of experimenting with “processing” each line read in as a future.

Setting the title in Terminal on OS X

Working through my Project Euler problems in Clojure, I wound up having a number of Terminal windows open at the same time: one for the REPL, one for a prompt to commit to my Project Euler git repo, one for a Midje program, one to start the Light Table Playground, and various others with other things I had going on.

With all of these windows, getting stacked on top of one another I was losing track of which Terminal window was which when I went to the Window menu for Terminal to get to the window I wanted.

I found this post Mac OS X Change the Terminal Window Title and then followed the instructions to get a nice little shell program setup to set the title of the window.

echo -n -e "33]0;$107"

Where I use the $1 instead the title itself, or a environment variable, per his two examples, to be able to have the first argument to the script, so now I can just run:

title "Light Table Playground"

I just figured I would share my find for anyone out there who hasn’t yet stumbled across it yet.

–Proctor