The Journey from Lambda to Unlambda

While scrounging around the Net looking at functional programming languages I came across Unlambda. The name by itself piqued my interest so I though I'd go have a look-see.

Here follows the troubled tale of the journey from Lambda to Unlambda ...
Nature of the Beast
It was created by David Madore and is a minimal functional programming language that was specifically built to make programming in it obtuse (or as the author's site refers to it as: "... fun and challenging"). It is based on combinatory logic but omits the lambda abstraction forcing you to rely on K and S combinators.

Beside hailing itself as a functional language it also succeeds in being an obfuscated programming language through severely restricting the set of allowed operations in the language and making it generally alien to programmers from more conventional languages.

It strictly only manipulates functions. A function is the only function parameter that you can pass in to a function and a function is the only construct that can be returned from a function. It relies heavily on its built-in k and s functions (K and S combinators) to get anything done.

The source is built to be intentionally incomprehensible for a human making it next to impossible to deduce what the intention of the program is by simply reading the source.

You are welcome to create your own functions, but be warned, you cannot name or save the custom function(s) because Unlambda does not have support for variables. Besides dispelling variables from its cloth you will also notice the lack of built-in support for data structures or code constructs (e.g. loops, conditionals, etc.). You are however welcome to build your own code constructs.

As an illustration, here is a loop that prints “Hello, world!” repeatedly, followed by an incrementing number of asterisks (an explanation of this severely limited subset of alphabet soup can be found here):

```s``sii`ki
``s``s`ks
   ``s``s`ks``s`k`s`kr
             ``s`k`si``s`k`s`k
                             `d````````````.H.e.l.l.o.,. .w.o.r.l.d.!
                      k
    k
`k``s``s`ksk`k.*

Unlambda is the little functional language that could however and in the face of all its consciously implemented obscurity it still manages to be Turing-complete.

Sure, but can it speak?
Here's the Unlambda equivalent for the trusty old "Hello world" we're used to:

`r```````````.H.e.l.l.o. .w.o.r.l.di

More examples, a tutorial and some HOWTOs can be found at David's site for Unlambda.

Secret Murmurings on Unlambda

• “It's disgusting — it's revolting — we love it.” CyberTabloid


• “Unlambda, the language in which every program is an IOUCC.” Encyclopædia Internetica


• “The worst thing to befall us since Intercal.” Computer Languages Today


• “The effect of reading an Unlambda program is like having your brains smashed out by a Lisp sexp wrapped around an ENIAC. You won't find anything like it west of Alpha Centauri.” The Hitch-Hacker's Guide to Programming

Epitaph
Unlambda is inevitably compared to Intercal, but unlike Intercal it has a kind of weird elegance; this is because Intercal gets in your way, but Unlambda simply fails to help you."

OS X File Name Subterfuge

While saving a file via the well known OS X file Save As dialog I noticed something really queer. The filename I had pasted in was magically altered to adhere to OS X's ideas on which characters are kosher for file/directory names!

Silent Substitution
To see the magic simply open TextEdit, create a new document (if you are not already presented with one) and add the following text to the document:

 watch: this: space:

Now, select the text, copy it and save the file with the selected text as the file name.

Et voilà!

Subterfuge Uncorked
The dialog magically converts the colons to hyphens (-) to ensure that you don't have to go through he whole 'This filename is not allowed' error cycle needlessly. Brill.

The reason for the substitution is that OS X prohibits the use of colon characters in file/directory names because this character is used to represent a directory in the HFS+ file system.

According to the HFS+ spec you can use any Unicode or ASCII (including NUL) characters. OS APIs may limit some of these characters for legacy reasons.

I love subtlety.

Dynamic Arbitrary Depth Hashes In Ruby

UPDATE: Charles Duan has an interesting article in a similar vein.

Arbitrary array and hash depth constructs cannot be created in Ruby in the way you would in Perl or PHP. The following will simply fail with an error:

irb(main):001:0> a = []
=> []
irb(main):002:0> a[1][2][3][4] = 1
NoMethodError: undefined method `[]' for nil:NilClass
      from (irb):2
irb(main):003:0> h = {}
=> {}
irb(main):004:0> h[1][2][3][4] = 5
NoMethodError: undefined method `[]' for nil:NilClass
      from (irb):4

When dynamically constructing your array or hash (aka Autovivification) this really gets in the way.

Autovivification
This is a dynamic data structure creation feature that can be found in Perl and PHP (those are the ones I know of). It allows you to create dynamic, complex, nested data structures based on the types implied in the syntax of the statement of code accessed through the data structure.

IOW, the act of fetching or storing a value at a leaf through a branch dynamically creates the branch(es) to the leaf.

VivifiedHash
One approach is to do the following:

  irb(main):011:0* VivifiedHash = Hash.new(&(p=lambda{|h,k| h[k] = Hash.new(&p)}))
  => {}
  irb(main):012:0> VivifiedHash[1][2][3][4] = 5
  => 5
  irb(main):013:0> VivifiedHash[1][2][3][4]
  => 5
  irb(main):014:0> VivifiedHash[1][2][3]
  => {4=>5}
  irb(main):015:0> VivifiedHash[1][2]
  => {3=>{4=>5}}
  irb(main):016:0> VivifiedHash[1]
  => {2=>{3=>{4=>5}}}
  irb(main):017:0> VivifiedHash
  => {1=>{2=>{3=>{4=>5}}}}

All this does is recursively assign the default key of the hash a new hash object as value. Each branch you specify in your assignment will recursively trigger the creation of a new hash.

Limitations
The limitation on this are of course that your data structure cannot contain anything but hashes as branches. Leaf nodes can be any data type though.

Sources

1. Ruby Hashes of Arbitrary Depth


2. Multidimensional arrays and hashes discussion on the RubyTalk mailing


3. Auto Vivification

Mechanized Scraping

Ever needed to interface with a web application without any real APIs? Take one step back from looking for a traditional API and use WWW::Mechanize to bend the application to your will.

WWW:Mechanize (inspired by "Andy Lester's":mailto://andy@petdance.com perl Mechanize module and written by Aaron Patterson) allows you to moonlight as a web User Agent (browser) from the comfort of your ruby scripting environment. It is great for building automated tests of your web applications, creating your favourite mashups and also to treat another web application's UI as the API to the application.

I've been working on some code that needs to gather reporting information from our billing system but I have no real access to the Oracle db in the back to get to the require stored procedures. So, I decided to simply use the UI as my API to the data and dusted my trusty old WWW:Mechanize (which uses Hpricot internally to parse and tokenise pages) off for the challenge.

It provides you with all the required tools to log in to a site (as well as automatic cookie handling), click on URI, submit forms and oh so much more. The only real feature currently lacking is support for JavaScript (they do however provide you with ideas on how to manoeuvre around some of the more mundane corers) which is becoming more and more painful in this Web2.0 world of ours.

WWW:Mechanize is quite easy to use so I am not going to write an exposé on the in's and out's of the lib or share with you its secrets that helped me to sate world hunger and bring peace to all. Instead, I will mention some of the bits that tripped me up while trying to make the web application dance to my flute.

Button Value Attributes
I was getting nowhere while trying to submit a form in the web application with some crafted values. Tinker here, tinker there and still no go. Try a browser and the application itself and things work like swiss cheesewatches.

Right you mangy ASP application, its time for the big guns! Out comes Wireshark and the debugging starts in earnest. First I dump a session from my script and then one from a browser.

From the diff of of the POST request I notice that the browser has the value attribute for the 'Save' button in the form set whereas I didn't. Because the form was posting back to itself I assume they had some code like (pseudocode):

if $submit == 'Submit'
then
    do your stuff when the form has been submitted
else
    display the normal form
end

Adding something that resembles the following did the trick:

form.buttons.name('some_convoluted_button_name').value = 'Submit'

Out of Buffer Error
A few more form hoops later and I started getting an error like:

hpricot/parse.rb:44:in `scan': ran out of buffer space on element <group>, starting on line 361. (Hpricot::ParseError?)

Hey?!

A quick look on the bug db for WWW:Mechanize on RubyForge listed this closed bug that has some application to our situation. The error messages are not the same (I assume this is the case due to an earlier version of Hpricot that was used when this was reported).

According to this TT it is a Hrpicot issue and refers to this TT.

According to the problem description:

An 'OUT OF BUFFER SPACE' error shuts down my whole app when I try to parse through an aspx page with an abnormally (or normally?) large viewstate stuffed into an input. Here's what it looks like:

    <input type="hidden" name="__VIEWSTATE"
        value="dDw3NzQ0ODQ2ODQ ... 11954 characters in total ... DsXdJfP+k" />

If I remove the large value it works fine. Is there a way hpricot could not exit when trying to parse a page like this?

DING! DING DING!

I am also scraping an ASP application and lo and behold I too have a ginormous __VIEWSTATE input tag in the page in question. I knew ASP was evil, but this?!

The limit on the buffer was of course a protection mechanism to ensure that a parsed page does not cause your computer to become the black hole of memory. The workaround for this is quite simple though, just increase the buffer

Okay, kids. [98] now has a buffer_size method.
    Hpricot.buffer_size = 262144
    doc = Hpricot(open("http://asp.net/big-viewstate-vomit.html"))

Perhaps I will find the wherewithal to fix the parser to read these massive attributes, but on-the-other-hand I don't want to encourage this disastrous behavior by ASP.NET!! You know?

"That's all good and well but we're not really using Hpricot directly, we're using WWW:Mechanize!", you all shout in unison.

True, true. All you do is simply add the buffer_size declaration after instantiating your shiny new WWW:Mechanize object like so:

agent = WWW::Mechanize.new
Hpricot.buffer_size = 204800

The default buffer size is defined in hpricot_scan.rl as:

[...]

#define BUFSIZE 16384

[...]

buffer_size = BUFSIZE;
if (rb_ivar_defined(self, rb_intern("@buffer_size")) == Qtrue) {
  bufsize = rb_ivar_get(self, rb_intern("@buffer_size"));
  if (!NIL_P(bufsize)) {
    buffer_size = NUM2INT(bufsize);
  }
}
buf = ALLOC_N(char, buffer_size);

[...]

That's a buffer of about 16KB for an attribute which under normal circumstances would be more than ample space for an attribute but working with ASP seems to be anything but normal.

In Closing
I have not had as much fun in quite some time. WWW:Mechanize had me clapping my little hands in glee while shouting "Wheeeeeeeeeee!" like a little kid that was given his first bunny rabbit just after having his second double espresso for the hour.

Ruby (Hpricot) Program Guide - III

As discussed in the previous article our next steps will be to refactor the constructor and provide an example of how we can use objects from the DSTVSchedule class to collect and display channels of our choice.

Let's change the constructor to take the channel ID, time offset (to account for different time zones) and the period ahead in time for which we want to gather schedule information as parameters. This will mean that we get rid of the custom hash class and tidy things up a little bit:

def initialize(channel=219, offset=2, period=30)
  start_date, end_date = get_search_dates(period)
  url = build_url(build_query_string(channel, start_date ,end_date))

  p "Start: #{start_date}  End: #{end_date}  URL: #{url}"

  @hp = Hpricot(open(url))
  @ic = Iconv.new('US-ASCII//TRANSLIT', 'UTF-8')
  @coder = HTMLEntities.new
  @schedule = process_html(@hp, offset)
end

def get_search_dates(period=30)
  [DateTime.now().strftime("%d %b %Y"), (DateTime.now()+period).strftime("%d %b %Y")]
end

def build_query_string(channel, start_date, end_date)
  urlencode({
    'channelid' => channel,
    'startDate' => start_date,
    'EndDate'   => end_date}) +
      '&sType=5&searchstring=&submit=Submit'
end

def build_url(query_string)
  host = 'www.mnet.co.za'
  cgi = '/schedules/default.asp?'
  "http://#{host}#{cgi}#{query_string}"
end

def urlencode(hash)
  hash.map {|k, v| "#{URI::encode(k.to_s)}=#{URI::encode(v.to_s)}"}.join('&')
end

We no longer statically define the query parameters in the constructor and therefore have no real need for the custom hash. We can still use the urlencode() method though and add it as a helper in the class.

The start and end dates for the query are calculated based on today's date and the period provided to the constructor as an argument.

We also dumped all that horrible looking query string and url variable construction code into separate methods.

The next step is to provide some automation to the channel schedule collection code for our example program. Look at the the HTML data in any of the search pages and you'll see the following (excerpt):

<select  name="channelid" class="ScheduleInputSelect">
    <option value="" >CHANNEL</option>
    <option value=246>actionX                                           </option>
    <option value=322>Activate                                          </option>
    <option value=496>Africa Magic</option>
    <option value=487>Africa Magic Channel (C-Band)                     </option>
    <option value=639>Africa Magic W4</option>
    <option value=417>Animal Planet                                     </option>
[...]
    <option value=254>TV Globo                                          </option>
    <option value=493>TV5 Afrique                                       </option>
    <option value=110>TV5 Afrique (Africa)                              </option>
    <option value=65>VH1                                               </option>
    <option value=67>ZEE TV                                            </option>
</select>

These are the channels that we can search for. What we need is to represent this information as an internal data structure that we can use to search for the channels we want. I suggest a hash that has the channel name as a key and the channel ID and offset as a tuple.

I am lazy so I'd prefer to avoid typing all that information up or manually trying to transform it in the editor. Perhaps we can use some good old command line ruby to chew up and spit out the code we need which we can then just cut 'n paste or import (depending on the editor you use).

Copy the HTML and drop it in a file somewhere. Let's call the file in.html and run it through this command line script (output is truncated):

$ ruby -n -e '$_=~/value=(\d+)\>(.+)\s+\</;if $1&&$2 then a=$1;b=$2;print "\# \"#{b.sub(/\s+$/,"")}\" => [#{a}, 120],\n" end' < in.html | head   
# "actionX" => [246, 120],
# "Activate" => [322, 120],
# "Africa Magic Channel (C-Band)" => [487, 120],
# "Animal Planet" => [417, 120],
# "B4U Movies" => [227, 120],
# "BBC Food" => [284, 120],
# "BBC Prime" => [121, 120],
# "BBC World" => [5, 120],
# "Bloomberg Information TV" => [8, 120],
# "Boomerang" => [314, 120],
[...]

Now take the output and place it in your script as a hash (as described above):

channels = {
  # "actionX" => [246, 120],
  # "Activate" => [322, 120],
  # "Africa Magic Channel (C-Band)" => [487, 120],
  # "Animal Planet" => [417, 120],
  # "B4U Movies" => [227, 120],
  "BBC Food" => [284, 120],
  "BBC Prime" => [121, 120],
  # "BBC World" => [5, 120],
  # "Bloomberg Information TV" => [8, 120],
  # "Boomerang" => [314, 120],
  # "BVN" => [270, 120],
  # "Canal+ Horizons" => [237, 120],
  # "Cartoon Network" => [13, 120],
  # "Cartoon Network (Africa)" => [219, 120],
  # "Cartoon Network (W4)" => [182, 120],
  # "Channel O - Sound Television" => [27, 120],
  # "China Central Television 4" => [15, 120],
  # "China Central Television 9 (Africa)" => [226, 120],
  # "CNBC" => [90, 120],
  # "CNBC (Africa)" => [194, 120],
  # "CNBC (W4)" => [187, 120],
  # "CNN International" => [18, 120],
  # "Deukom - 3SAT" => [165, 120],
  # "Deukom - ARD" => [93, 120],
  # "Deukom - DW" => [94, 120],
  # "Deukom - PRO 7" => [164, 120],
  # "Deukom - RTL" => [91, 120],
  # "Deukom - SAT 1" => [92, 120],
  # "Deukom - ZDF" => [95, 120],
  "Discovery Channel" => [21, 120],
  # "E-Entertainment" => [646, 120],
  "ESPN" => [24, 120],
  # "eTV" => [111, 120],
  # "Fashion TV" => [145, 120],
  # "Fashion TV (Africa)" => [196, 120],
  # "Fashion TV (W4)" => [216, 120],
  "GO" => [542, 120],
  # "Go  (K-World Teen)" => [341, 120],
  "Hallmark Entertainment Network" => [32, 120],
  "History Channel" => [484, 120],
  # "History Channel (Africa)" => [485, 120],
  # "K-TV World" => [36, 120],
  # "KTV (Indian Bouquet)" => [501, 120],
  # "kykNET" => [112, 120],
  # "M-Net Domestic" => [39, 120],
  "M-Net East (Africa)" => [40, 120],
  "M-Net Series" => [75, 120],
  # "MK89" => [592, 120],
  # "Movie Magic (Africa)" => [57, 120],
  "Movie Magic 2 (Africa)" => [234, 120],
  # "Movie Magic 2 (W4)" => [233, 120],
  # "MTV" => [42, 120],
  # "MTV Base" => [69, 120],
  "National Geographic" => [102, 120],
  # "NDTV" => [499, 120],
  # "Parliamentary Service" => [45, 120],
  # "Pay Per View" => [109, 120],
  "Reality TV" => [248, 120],
  # "Rhema Network" => [46, 120],
  # "RTPi" => [48, 120],
  # "SABC 1" => [84, 120],
  # "SABC 2" => [85, 120],
  # "SABC 3" => [86, 120],
  # "SABC Africa" => [87, 120],
  # "SIC" => [255, 120],
  # "Sky News" => [120, 120],
  "Sony Entertainment" => [228, 90],
  # "Summit" => [104, 120],
  # "Sun TV" => [500, 120],
  # "SuperSport" => [52, 120],
  # "SuperSport 2" => [54, 120],
  # "SuperSport 3" => [80, 120],
  # "SuperSport 3 (W4)" => [172, 120],
  # "SuperSport 5" => [208, 120],
  # "SuperSport 5 (Africa)" => [252, 120],
  # "SuperSport 5 (W4)" => [251, 120],
  # "SuperSport 6" => [209, 120],
  # "SuperSport 7 (C-Band)" => [580, 120],
  # "SuperSport Zone Mosaic" => [235, 120],
  # "TellyTrack" => [34, 120],
  # "Travel Channel" => [61, 120],
  # "Trinity Broadcasting Network" => [276, 120],
  # "Turner Classic Movies" => [59, 120],
  # "Turner Classic Movies (Africa)" => [60, 120],
  # "Turner Classic Movies (W4)" => [181, 120],
  # "TV Globo" => [254, 120],
  # "TV5 Afrique" => [493, 120],
  # "TV5 Afrique (Africa)" => [110, 120],
  # "VH1" => [65, 120],
  # "ZEE TV" => [67, 120]
}

You'll notice I have removed the comments from any of the channels I want (I recommend you do the same for the channels you may be interested in). I also added a default time offset of 2 hours (120 minutes) for most of the channels to adjust the time for my time zone. You can change this in the command line ruby filter above to suit your needs.

All we need to do now is wrap our object creation and the output from it in a loop and we're off:

channels.keys.each do |channel|
  p "Channel: #{channel}"
  schedule = DSTVSchedule.new(channels[channel][0], channels[channel][1], 30)
  schedule.print_schedule
  print "\n\n"
end

All done. Here is the complete script source listing:

#!/usr/bin/ruby

class DSTVSchedule
  require 'rubygems'
  require 'hpricot'
  require 'open-uri'
  require 'htmlentities'
  require 'iconv'
  require 'collections/sequenced_hash'

  def initialize(channel=219, offset=2, period=30)
    start_date, end_date = get_search_dates(period)
    url = build_url(build_query_string(channel, start_date ,end_date))

    p "Start: #{start_date}  End: #{end_date}  URL: #{url}"

    @hp = Hpricot(open(url))
    @ic = Iconv.new('US-ASCII//TRANSLIT', 'UTF-8')
    @coder = HTMLEntities.new
    @schedule = process_html(@hp, offset)
  end

  def process_html(hp, offset)
    schedule = SequencedHash.new
    date = ""
    time = ""
    (hp/"td").each do |line|
      case line.inner_html
      when /ScheduleChannel/
        @channel = sanitize((line/"[@class='ScheduleChannel']").inner_html)
      when /(ScheduleDate|date)/
        date = utf7((line/"[@class='ScheduleDate']|[@class=date]").inner_html)
        schedule[date] = SequencedHash.new
      when /ScheduleTime/
        time = sanitize((line/"[@class='ScheduleTime']").inner_html)
        time = (Time.parse("#{date} #{time}") + (60 * offset)).strftime("%H:%M")
        schedule[date][time] = []
      when /ScheduleTitle/
        schedule[date][time] << sanitize((line/"[@class='ScheduleTitle']").inner_html)
      when /\<p\>/
        schedule[date][time] << sanitize((line/"p").inner_html)
      end
    end

    schedule
  end

  def to_s
    self.print_schedule("\t")
  end

  alias :to_tdt :to_s

  def to_csv
    ##TODO - Add channel to the output
    self.print_schedule(",")
  end

  def print_schedule(separator="||")
    sep = separator
    @schedule.keys.each do |date|
      @schedule[date].keys.each do |time|
        print [date, time, @schedule[date][time][0], @schedule[date][time][1]].join(sep) + "\n"
      end
    end
  end

  protected

  def sanitize(string)
    string.gsub!(/\<\!\-\-.+$/, '')  # remove HTML comments to the end of the line
    string.gsub!(/^\s+/, '')  # remove leading whitespace
    string.gsub!(/\s+$/, '')  # remove trailing whitespace
    string
  end

  def utf7(string="")
    @ic.iconv(@coder.decode(string))
  end

  def get_search_dates(period=30)
    [DateTime.now().strftime("%d %b %Y"), (DateTime.now()+period).strftime("%d %b %Y")]
  end

  def build_query_string(channel, start_date, end_date)
    urlencode({
      'channelid' => channel,
      'startDate' => start_date,
      'EndDate'   => end_date}) +
        '&sType=5&searchstring=&submit=Submit'
  end

  def build_url(query_string)
    host = 'www.mnet.co.za'
    cgi = '/schedules/default.asp?'
    "http://#{host}#{cgi}#{query_string}"
  end

  def urlencode(hash)
    hash.map {|k, v| "#{URI::encode(k.to_s)}=#{URI::encode(v.to_s)}"}.join('&')
  end
end


#
# Main
#
channels = {
  # "actionX" => [246, 120],
  # "Activate" => [322, 120],
  # "Africa Magic Channel (C-Band)" => [487, 120],
  # "Animal Planet" => [417, 120],
  # "B4U Movies" => [227, 120],
  "BBC Food" => [284, 120],
  "BBC Prime" => [121, 120],
  # "BBC World" => [5, 120],
  # "Bloomberg Information TV" => [8, 120],
  # "Boomerang" => [314, 120],
  # "BVN" => [270, 120],
  # "Canal+ Horizons" => [237, 120],
  # "Cartoon Network" => [13, 120],
  # "Cartoon Network (Africa)" => [219, 120],
  # "Cartoon Network (W4)" => [182, 120],
  # "Channel O - Sound Television" => [27, 120],
  # "China Central Television 4" => [15, 120],
  # "China Central Television 9 (Africa)" => [226, 120],
  # "CNBC" => [90, 120],
  # "CNBC (Africa)" => [194, 120],
  # "CNBC (W4)" => [187, 120],
  # "CNN International" => [18, 120],
  # "Deukom - 3SAT" => [165, 120],
  # "Deukom - ARD" => [93, 120],
  # "Deukom - DW" => [94, 120],
  # "Deukom - PRO 7" => [164, 120],
  # "Deukom - RTL" => [91, 120],
  # "Deukom - SAT 1" => [92, 120],
  # "Deukom - ZDF" => [95, 120],
  "Discovery Channel" => [21, 120],
  # "E-Entertainment" => [646, 120],
  "ESPN" => [24, 120],
  # "eTV" => [111, 120],
  # "Fashion TV" => [145, 120],
  # "Fashion TV (Africa)" => [196, 120],
  # "Fashion TV (W4)" => [216, 120],
  "GO" => [542, 120],
  # "Go  (K-World Teen)" => [341, 120],
  "Hallmark Entertainment Network" => [32, 120],
  "History Channel" => [484, 120],
  # "History Channel (Africa)" => [485, 120],
  # "K-TV World" => [36, 120],
  # "KTV (Indian Bouquet)" => [501, 120],
  # "kykNET" => [112, 120],
  # "M-Net Domestic" => [39, 120],
  "M-Net East (Africa)" => [40, 120],
  "M-Net Series" => [75, 120],
  # "MK89" => [592, 120],
  # "Movie Magic (Africa)" => [57, 120],
  "Movie Magic 2 (Africa)" => [234, 120],
  # "Movie Magic 2 (W4)" => [233, 120],
  # "MTV" => [42, 120],
  # "MTV Base" => [69, 120],
  "National Geographic" => [102, 120],
  # "NDTV" => [499, 120],
  # "Parliamentary Service" => [45, 120],
  # "Pay Per View" => [109, 120],
  "Reality TV" => [248, 120],
  # "Rhema Network" => [46, 120],
  # "RTPi" => [48, 120],
  # "SABC 1" => [84, 120],
  # "SABC 2" => [85, 120],
  # "SABC 3" => [86, 120],
  # "SABC Africa" => [87, 120],
  # "SIC" => [255, 120],
  # "Sky News" => [120, 120],
  "Sony Entertainment" => [228, 90],
  # "Summit" => [104, 120],
  # "Sun TV" => [500, 120],
  # "SuperSport" => [52, 120],
  # "SuperSport 2" => [54, 120],
  # "SuperSport 3" => [80, 120],
  # "SuperSport 3 (W4)" => [172, 120],
  # "SuperSport 5" => [208, 120],
  # "SuperSport 5 (Africa)" => [252, 120],
  # "SuperSport 5 (W4)" => [251, 120],
  # "SuperSport 6" => [209, 120],
  # "SuperSport 7 (C-Band)" => [580, 120],
  # "SuperSport Zone Mosaic" => [235, 120],
  # "TellyTrack" => [34, 120],
  # "Travel Channel" => [61, 120],
  # "Trinity Broadcasting Network" => [276, 120],
  # "Turner Classic Movies" => [59, 120],
  # "Turner Classic Movies (Africa)" => [60, 120],
  # "Turner Classic Movies (W4)" => [181, 120],
  # "TV Globo" => [254, 120],
  # "TV5 Afrique" => [493, 120],
  # "TV5 Afrique (Africa)" => [110, 120],
  # "VH1" => [65, 120],
  # "ZEE TV" => [67, 120]
}

channels.keys.each do |channel|
  p "Channel: #{channel}"
  schedule = DSTVSchedule.new(channels[channel][0], channels[channel][1], 30)
  schedule.print_schedule
  print "\n\n"
end

I hope these articles have tickled your lobes and gets you to go explore Hpricot and the Wonderful World of Web Scraping.