Blag blogs!

My first post on Ada

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Thu, 01 Oct 2015 20:27:00 +0000

Well...it might be my fist post on Ada but it's not my first encounter with Ada -;) I learned it about 10 years ago or more...but until now...I didn't give to much of a use...

If you're wondering...what's Ada? Well...according to Wikipedia...

Ada is a structured, statically typed, imperative, wide-spectrum, and object-oriented high-level computer programming language, extended from Pascal and other languages.

So yes...it pretty much looks like Pascal...but way more strict...and complex...

As usual with my "My first post on..." I build a Fibonacci List generator...something simple to start re-learning the language...so here it goes...

fibonacci.adb
with Ada.Text_IO; with Ada.Strings.Unbounded; use Ada.Strings.Unbounded; procedure Fibonacci is package IO renames Ada.Text_IO; package Number_IO is new Ada.Text_IO.Integer_IO (Integer); num : Integer; function Fib(num:Integer;a:Integer;b:Integer) return Unbounded_String is result : Unbounded_String; begin if a > 0 and num > 1 then result := result & Integer'Image(a+b) & " " & Fib(num-1,a+b,a); elsif a = 0 then result := Integer'Image(a) & " " & Integer'Image(b) & " " & Integer'Image(a+b) & " " & Fib(num-1,a+b,b); end if; return result; end Fib; begin IO.Put("Enter a number: "); Number_IO.Get(num); IO.Put(To_String(Fib(num,0,1))); end Fibonacci;

fibonacci.adb

with Ada.Text_IO;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;

procedure Fibonacci is
 package IO renames Ada.Text_IO;
 package Number_IO is new Ada.Text_IO.Integer_IO (Integer);
 num : Integer;
 
 function Fib(num:Integer;a:Integer;b:Integer) return Unbounded_String is
 result : Unbounded_String;
 begin
  if a > 0 and num > 1 then
   result := result & Integer'Image(a+b) & " " & Fib(num-1,a+b,a);
  elsif a = 0 then
   result := Integer'Image(a) & " " & Integer'Image(b) & " " & 
             Integer'Image(a+b) & " " & Fib(num-1,a+b,b);
  end if;
  return result;
 end Fib;
 
begin
 IO.Put("Enter a number: ");
 Number_IO.Get(num);
 IO.Put(To_String(Fib(num,0,1)));
end Fibonacci;

And here are the screenshots...

Well...that's was fairly easy...but of course I needed to investigate a little bit...so the challenge will be when I start working on my LED Numbers app... -:P

Greetings,

Blag.
Development Culture.

SAP HANA on the OCaml hump

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Tue, 29 Sep 2015 20:03:00 +0000

This post was originally posted on SAP HANA on the OCaml hump.

OCaml is an industrial strength programming language supporting functional, imperative and object-oriented styles.

Sounds nice, right? OCaml is the next step of the Caml programming language.

Having learning other functional programming languages like Haskell and Erlang, OCaml was the next obvious choice for me…so I decided to start learning it…not an easy task for sure…but really fun and enlighten.

So…no example or demonstration would be complete if we didn’t hook it up with SAP HANA, right? So…let’s go and do it -;)

First, we need to create a Calculation View and call it “FLIGHTS_BY_CARRIER”. It will be composed of two tables, SCARR and SFLIGHT.

First, we need to create a Join object and link the table by MANDT and CARRID. From here select the following fields as output MANDT, CARRID, CARRNAME, PRICE and CURRENCY.

Then create an Aggregation object selecting the fields CARRNAME, PRICE (As Aggregated Column) and CURRENCY. Filter the CURRENCY field by ‘USD’.

Then create a Projection object and select only PRICE and CARRNAME.

On the Semantics object make sure to select “CROSS CLIENT” as the Default Client.

Now, switch to the SAP HANA Development View and create a new repository. Call it “Flights”.

Create a new “XS Engine” project and call it “Flights” as well. Link it to the “Flights” repository.

Create an empty “.xsapp” file.

Create a file called “.xsaccess” with the following code.

.xsaccess
{ "exposed" : true, "authentication" : [ { "method" : "Basic" } ] }

Finally create a file called “flights.xsodata” with the following code

flights.xodata
service { "Blag/FLIGHTS_BY_CARRIER.calculationview" as "FLIGHTS" keys generate local "Id"; }

Activate your project and launch it on your browser, you should see something like this…

The SAP HANA part is done…so we can move into the OCaml part…

For first timers, OPAM (the package manager for OCaml can be tricky and sometimes frustrating), so let’s make your lives easier by following this single easy steps…on a terminal session type this…

• opam init

• eval `opam config env`

• opam switch 4.01.0

• eval `opam config env`

• opam install core utop core_extended async uri yojson cohttp lwt ezjsonm

It will take a while but by installing all the required packages in a single command, prevents errors from happening.

To code for OCaml I use one of the most awesome editors I have ever found…Geany. It comes almost pre-configured to handle a lot of programming languages, but just to make sure, here’s how I configure it to work with OCaml.

First, create a file and save it as OCaml_HANA.ml

Then, click on the “Choose more build actions” button

The little half arrow on the right of the brown brick looking button. This will open the following screen

On Compile put the following

corebuild -pkg yojson,cohttp.async,cohttp.lwt,lwt,ezjsonm "%e.native"

And on Execute put

“./%e.native”

With that, we should be more than ready to start coding -:) Copy and paste the following code…

OCaml_HANA.ml
open Core.Std open Yojson.Basic.Util open Ezjsonm let get_definition_from_json json = let json = Ezjsonm.from_string(json) in let json = Ezjsonm.(find json ["d";"results"]) in let json = Ezjsonm.to_string(json) in let json = Yojson.Basic.from_string(json) in let json = Yojson.Basic.Util.to_list json in let carrname = Yojson.Basic.Util.filter_member "CARRNAME" json in let carrname = Yojson.Basic.Util.filter_string carrname in let price = Yojson.Basic.Util.filter_member "PRICE" json in let price = Yojson.Basic.Util.filter_string price in printf "Reading SAP HANA from OCaml\n\n"; for i = 0 to List.length(carrname) - 1 do printf "%s: %s\n" (List.nth_exn carrname i) (List.nth_exn price i) done let fetch uri = let cred = Cohttp.Auth.string_of_credential(`Basic("SYSTEM", "YourPassword")) in let headers = Cohttp.Header.init() in let headers = Cohttp.Header.add headers "Authorization" cred in let open Lwt in Cohttp_lwt_unix.Client.get ~headers:headers uri >>= fun (_,body) -> Cohttp_lwt_body.to_string_list body >>= fun strings -> return(get_definition_from_json (String.concat strings)) let () = let hana_uri = Uri.of_string "http://YourServer:8000/Flights/flights.xsodata /FLIGHTS?$format=json" in Lwt_main.run (fetch hana_uri)

OCaml_HANA.ml

open Core.Std
open Yojson.Basic.Util
open Ezjsonm

let get_definition_from_json json =
 let json = Ezjsonm.from_string(json) in
 let json = Ezjsonm.(find json ["d";"results"]) in
 let json = Ezjsonm.to_string(json) in
 let json = Yojson.Basic.from_string(json) in
 let json = Yojson.Basic.Util.to_list json in
 let carrname = Yojson.Basic.Util.filter_member "CARRNAME" json in
 let carrname = Yojson.Basic.Util.filter_string carrname in
 let price = Yojson.Basic.Util.filter_member "PRICE" json in
 let price = Yojson.Basic.Util.filter_string price in
 printf "Reading SAP HANA from OCaml\n\n";
 for i = 0 to List.length(carrname) - 1 do
  printf "%s: %s\n" (List.nth_exn carrname i) (List.nth_exn price i)
done

let fetch uri =
 let cred = Cohttp.Auth.string_of_credential(`Basic("SYSTEM", "YourPassword")) in
 let headers = Cohttp.Header.init() in 
 let headers = Cohttp.Header.add headers "Authorization" cred in
 let open Lwt in
 Cohttp_lwt_unix.Client.get ~headers:headers uri 
 >>= fun (_,body) ->
 Cohttp_lwt_body.to_string_list body
 >>= fun strings ->
 return(get_definition_from_json (String.concat strings))  

let () =
  let hana_uri = Uri.of_string "http://YourServer:8000/Flights/flights.xsodata

                                /FLIGHTS?$format=json"
  in Lwt_main.run (fetch hana_uri)

Save your file, press the “Compile the current file” button. The first on the previous images which shows a triangle with an arrow and a ball (all in nice 3D) and then press the “Run or view the current file” button. Last one on the previous image which shows two engines.

You will notice that it comes pretty fast…

Now…something funny about my code…and that might be because of two simple reasons…

• I’m still learning OCaml
• The documentation for external packages is almost non-existent (Actually, I need to browse the GitHub source codes in order to achieve most of the code)

So…the funny thing is that I’m using two different JSON libraries to actually read the ODATA generated by SAP HANA…by using only one I couldn’t manage to get the information that I needed…so using both and extracting pieces from here and there I actually got what I wanted…not so fun when you are doing it…but in the end there a big reward on finally being able to compile it and get the desired output -;)

Greetings,

Blag.

Development Culture.

Amazon Alexa and Philips Hue

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Mon, 28 Sep 2015 20:34:00 +0000

This post was originally posted on Amazon Alexa and Philips Hue.

If you are an SAP Employee, please follow us on Jam.

Since we got the Amazon Alexa on the d-shop here at SAP Labs Silicon Valley...I have been looking for new ways to make it interact with many things...so a couple of days my good friend and colleague Aaron Williams asked me about the Philips Hue...

At first...I wasn't sure it was going to work, because as everybody knows...the Hue needs to be on the same network to be able to work...and Amazon Lambda is sitting on a server who knows where...so I start looking into it...

When using the Amazon Alexa app we can hook up the Hue to allow Alexa to turn on and off the light...but nothing more...

You need to go to Settings --> Connected Home -> Discover Devices (It will ask you to push the button on the Hue Bridge).

For sure...this wasn't enough for me...so I kept thinking about it and realized that "Hey!...the Philips Hue works when you want to change the lights...and it does it remotely...so there must be a way to do it"...

Gladly...I found this blog...Philips Hue Remote API Explained...where the author basically explains how you can "trick" Hue into thinking that you are connecting from your IPhone...hence...you're doing a remote connection...genius if you ask me -;)

For this to work you need to create a meethue account...just singing using your Google account didn't worked for me...

Basically, you need to first find your BridgeId by going here https://www.meethue.com/api/nupn
Get your access token by going here www.meethue.com/en-US/api/gettoken?devicename=iPhone+5&appid=hueapp&deviceid=**BRIDGEID**
On the "Back to the App" button, copy the link for the AccessToken that will look like this phhueapp://sdk/login/**ACCESSTOKEN**

By the way...if you find something like this at the end "%3D" simply change it for an "="

Having both the BridgeId and AccessToken we should be ready to go -;)

We need to create both a Function and a Skill...please refer to this blog Amazon Alexa and SAP HANA to create them...

The function will be called getLights and the skill Lights. The Invocation Name will be "lights".

Here's the Interaction Model that we're going to use...

Intent Schema
{ "intents": [ { "intent": "GetLightsIntent", "slots": [ { "name": "color", "type": "LITERAL" } ] }, { "intent": "HelpIntent", "slots": [] } ] }

Sample Utterances
GetLightsIntent color {red\|color} GetLightsIntent color {blue\|color} GetLightsIntent color {green\|color} GetLightsIntent color {pink\|color} GetLightsIntent color {purple\|color} GetLightsIntent color {aqua\|color} GetLightsIntent color {white\|color} GetLightsIntent color {yellow\|color} GetLightsIntent color {black\|color} HelpIntent help HelpIntent help me HelpIntent what can I ask you HelpIntent get help HelpIntent to help HelpIntent to help me HelpIntent what commands can I ask HelpIntent what commands can I say HelpIntent what can I do HelpIntent what can I use this for HelpIntent what questions can I ask HelpIntent what can you do HelpIntent what do you do HelpIntent how do I use you HelpIntent how can I use you HelpIntent what can you tell me HelpIntent how do i change colors

Sample Utterances

GetLightsIntent color {red|color}
GetLightsIntent color {blue|color}
GetLightsIntent color {green|color}
GetLightsIntent color {pink|color}
GetLightsIntent color {purple|color}
GetLightsIntent color {aqua|color}
GetLightsIntent color {white|color}
GetLightsIntent color {yellow|color}
GetLightsIntent color {black|color}

HelpIntent help
HelpIntent help me
HelpIntent what can I ask you
HelpIntent get help
HelpIntent to help
HelpIntent to help me
HelpIntent what commands can I ask
HelpIntent what commands can I say
HelpIntent what can I do
HelpIntent what can I use this for
HelpIntent what questions can I ask
HelpIntent what can you do
HelpIntent what do you do
HelpIntent how do I use you
HelpIntent how can I use you
HelpIntent what can you tell me
HelpIntent how do i change colors

Now...the most important thing is the code -:P

Let’s create a folder and call it “Lights” or something nice like that…then create a folder called “src”. Copy the code from here...and create a file called “AlexaSkills.js”

We’re going to need to install the request package on our function, so do the following on a terminal

sudo npm install --prefix=~/Alexa/Lights/src request

This will create a folder called “node_modules” with the package in our project folder…then create a file called “index.js” and copy and paste the following code…

index.js
var request = require("request") , AlexaSkill = require('./AlexaSkill') , APP_ID = 'YourAPPId' , TOKEN = 'YourAccessToken'; var error = function (err, response, body) { console.log('ERROR [%s]', err); }; var getJsonFromLights = function(color,callback){ switch(color){ case 'red': x = 0.674; y = 0.322; break; case 'green': x = 0.408; y = 0.517; break; case 'blue': x = 0.168; y = 0.041; break; case 'white': x = 0.3227; y = 0.329; break; case 'yellow': x = 0.4317; y = 0.4996; break; case 'purple': x = 0.2725; y = 0.1096; break; case 'orange': x = 0.5562; y = 0.4084; break; case 'pink': x = 0.3944; y = 0.3093; break; case 'black': x = 0.168; y = 0.041; break; case 'aqua': x = 0.2858; y = 0.2747; break; default: x = 0.3227; y = 0.329; break; } var options = { method: 'POST', url: 'https://www.meethue.com/api/sendmessage', qs: { token: TOKEN}, headers: { 'content-type': 'application/x-www-form-urlencoded' }, body: 'clipmessage={ bridgeId: "YourBridgeId", clipCommand: {url:"/api/0/lights/1/state", method: "PUT", body: {xy:[' + x + ',' + y + ']}}}' }; var error_log = ""; request(options, function (error, response, body) { if (!error) { error_log = color; }else{ error_log = "There was a mistake"; } callback(error_log); }); } var handleLightsRequest = function(intent, session, response){ getJsonFromLights(intent.slots.color.value, function(data){ var text = 'The color has been changed to ' + data; var cardText = 'The color has been changed to ' + intent.slots.color.value; var heading = 'The color has been changed to ' + intent.slots.color.value; response.tellWithCard(text, heading, cardText); }); }; var Lights = function(){ AlexaSkill.call(this, APP_ID); }; Lights.prototype = Object.create(AlexaSkill.prototype); Lights.prototype.constructor = Lights; Lights.prototype.eventHandlers.onSessionStarted = function(sessionStartedRequest, session){ console.log("onSessionStarted requestId: " + sessionStartedRequest.requestId + ", sessionId: " + session.sessionId); }; Lights.prototype.eventHandlers.onLaunch = function(launchRequest, session, response){ // This is when they launch the skill but don't specify what they want. var output = 'Welcome to Hue Lights. Please say a color'; var reprompt = 'Which color would you like?'; response.ask(output, reprompt); console.log("onLaunch requestId: " + launchRequest.requestId + ", sessionId: " + session.sessionId); }; Lights.prototype.intentHandlers = { GetLightsIntent: function(intent, session, response){ handleLightsRequest(intent, session, response); }, HelpIntent: function(intent, session, response){ var speechOutput = 'Change your Hue Light to any color. Which color would you like?'; response.ask(speechOutput); } }; exports.handler = function(event, context) { var skill = new Lights(); skill.execute(event, context); };

index.js

var request = require("request")
  , AlexaSkill = require('./AlexaSkill')
  , APP_ID     = 'YourAPPId'
  , TOKEN = 'YourAccessToken';

var error = function (err, response, body) {
    console.log('ERROR [%s]', err);
};

var getJsonFromLights = function(color,callback){
switch(color){
 case 'red':
  x = 0.674; y = 0.322; break;
 case 'green':
  x = 0.408; y = 0.517; break;
 case 'blue':
  x = 0.168; y = 0.041; break;
 case 'white':
  x = 0.3227; y = 0.329; break;
 case 'yellow':
  x = 0.4317; y = 0.4996; break;
 case 'purple':
  x = 0.2725; y = 0.1096; break;
 case 'orange':
  x = 0.5562; y = 0.4084; break;
 case 'pink':
  x = 0.3944; y = 0.3093; break;
 case 'black':
  x = 0.168; y = 0.041; break;    
 case 'aqua':
  x = 0.2858; y = 0.2747; break;
 default:
  x = 0.3227; y = 0.329; break;
}

var options = { method: 'POST',
                url: 'https://www.meethue.com/api/sendmessage',
                qs: { token: TOKEN},
                headers: { 'content-type': 'application/x-www-form-urlencoded' },
                body: 'clipmessage={ bridgeId: "YourBridgeId",

                                     clipCommand:  {url:"/api/0/lights/1/state",

                                     method: "PUT", body: {xy:[' + x + ',' + y + ']}}}' };

var error_log = "";

request(options, function (error, response, body) {
 if (!error) {
  error_log = color;
 }else{
  error_log = "There was a mistake";
 }
 callback(error_log);
    });
}

var handleLightsRequest = function(intent, session, response){
  getJsonFromLights(intent.slots.color.value, function(data){
 var text = 'The color has been changed to ' + data;
    var cardText = 'The color has been changed to ' + intent.slots.color.value;

    var heading = 'The color has been changed to ' + intent.slots.color.value;
    response.tellWithCard(text, heading, cardText);
  });
};

var Lights = function(){
  AlexaSkill.call(this, APP_ID);
};

Lights.prototype = Object.create(AlexaSkill.prototype);
Lights.prototype.constructor = Lights;

Lights.prototype.eventHandlers.onSessionStarted = function(sessionStartedRequest, session){
  console.log("onSessionStarted requestId: " + sessionStartedRequest.requestId
      + ", sessionId: " + session.sessionId);
};

Lights.prototype.eventHandlers.onLaunch = function(launchRequest, session, response){
  // This is when they launch the skill but don't specify what they want.

  var output = 'Welcome to Hue Lights. Please say a color';

  var reprompt = 'Which color would you like?';

  response.ask(output, reprompt);

  console.log("onLaunch requestId: " + launchRequest.requestId
      + ", sessionId: " + session.sessionId);
};

Lights.prototype.intentHandlers = {
  GetLightsIntent: function(intent, session, response){
    handleLightsRequest(intent, session, response);
  },

  HelpIntent: function(intent, session, response){
    var speechOutput = 'Change your Hue Light to any color. Which color would you like?';
    response.ask(speechOutput);
  }
};

exports.handler = function(event, context) {
    var skill = new Lights();
    skill.execute(event, context);
};

When it's done...simply compress the node_module folder, AlexaSkills.js and index.js files into a .zip file called Lights.zip and upload it to your Amazon Lambda...

To call this skill on Alexa...you can do the following...

Alexa, turn on lamp 1 (Taking into account that your light my be called different)
Alexa, ask lights for color blue
Alexa, turn off lamp 1

You can see the available colors in the code...but just in case they should be...

Red
Green
Blue
Aqua
Pink
White
Black
Yellow
Purple
Orange

And of course...here's the video -:D

Greetings,

Blag.
Development Culture.

R - My journey so far

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Thu, 24 Sep 2015 22:13:00 +0000

The first time I heard about R, was about 4 years ago...a couple of week after I joined SAP. At that time I read in one of our internal documents that SAP HANA was going to be able to interact with the R programming Language.

At first, I was totally clueless about R...I had never heard from it before...so I of course start looking for some more information, download R and RStudio and start learning how to use it...

After some time...I posted my first blog talking about R...that was on November 28, 2011...the blog was Dealing with R and HANA...

After that I kept learning and using it whenever it was suitable...and I end up writing my most successful blog on the SAP Community Network...that was on May 21, 2012.

When SAP HANA met R - First kiss

That up to now, has 21,879 views and 62 comments, 16 likes and 32 bookmarks.

R is huge...it really is...there's thousands of packages that solve thousands of issues...so that's when I start reading R related books from my good friends at Packt Publishing...

Web Application Development with R using Shiny (See my review here).

As I was improving my R skills...I knew that something was missing...I really didn't knew much about Statistics and my Machine Learning skills were pretty dull as well...that's when I read another awesome book...and I think my favorite book on R so far...

Machine Learning with R (See my review here).

Another topic that it's interesting is Social Media...and how to get value out of it...

Social Media Mining with R (See my review here).

If you're wondering how Social Media can be used with R, then please take a look at my blog Getting Flexible with SAP HANA where I use SAP HANA, R, Twitter and Schema Flexibility to analyze hashtags that can be further explored using for example SAP Lumira.

If you are into the Bioinformatics world...which I'm not -:( You should appreciate this book...

Bioinformatics with R Cookbook (See my review here).

And there are some more books that I haven't read yet, but might help you to get started into the R world like...

Data Manipulation with R

R Data Visualization Cookbook

Instant R Starter

So...why are all this books important? Well...obviously, they are all about R and R is amazing and becoming more important each and every day...

Look at this video to realize why Data Science is a hot topic to learn...

Or you just can download it as a nice PDF for offline reading http://bit.ly/1MryNha

Also...by just reading this blog post...you have the opportunity to buy any of these books with a 50% discount by using this code at checkout time...

SIXRB50

A big opportunity NOT to be missed out...

The validity of codes till 31st October. Limited copies are available.

Greetings,

Blag.

Development Culture.

Join us for Geeky Thursday on October

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Thu, 24 Sep 2015 19:56:00 +0000

What's Geeky Thursday?

It's an event that happens every Thursday per week. An hour and little bit more of "hands-on" session where not so common programming languages (ex: Lua, Julia, R, Haskell) and Programming Paradimgs (Functional, Stack Based, Logical, Object-Oriented) are being presented.

Why Geeky Thursday?

Because Developers...because knowing just a couple of programming languages is not enough...because learning another paradigm can expand your horizons and make a better developer.

Geeky Thursday is hands-on...do I need my laptop?

Well...it really depends on you...the source code is going to be available...it's going to be explained and run on-site...there's not going to be live typing...but it's always better if you can compile and run the examples yourself...

Is Geeky Thursday only about Programming?

No...without any aims to become a "Brown Bag Session"...Geeky Thursday looks forward to become a "Mini Meetup" space...where cool things can be explored.

Is Geeky Thursday held only on Silicon Valley?

For now...it is...but...if you manage or you are in touch with a d-shop manager, ask him/her to get in touch with me (a.tejada.galindo@sap.com)...I would be more than happy to share my slides and anything needed to expand Geeky Thursday to other locations.

Is any space limitation?

Yes, we can invite 10 people from SAP and we have space for 5 people that external to SAP. Depending on the attendance level we might increase this values.

Can I host a Geeky Thursday event?

Of course! You're more than welcome! Just get in touch with me and will be setup an slot for you!

Scheduled Geeky Thursdays

R Programming Language --> October 8 from 1:00 to 2:00pm (d-shop on Building 9 at SAP Labs Silicon Valley)

For SAP Employees

https://jam4.sapjam.com/groups/sh2Kp26QQkHwkMPFAEqAD9/events/K7BJsIiucH7XjLszzcO0Eh

For Externals

https://www.eventbrite.com/myevent?eid=18783268261

R is a programming language and software environment for statistical computing and graphics. Please join us to learn the basics of R.

You can download R from here https://cran.r-project.org/

You can download RStudio from here https://www.rstudio.com/

Julia Programming Language --> October 15 from 1:00 to 2:00pm (d-shop on Building 9 at SAP Labs Silicon Valley)

For SAP Employees

https://jam4.sapjam.com/groups/sh2Kp26QQkHwkMPFAEqAD9/events/5FieiznXF6EgaGfg34qKdd

For Externals

https://www.eventbrite.com/myevent?eid=18783317408

Julia is a high-level dynamic programming language designed to address the requirements of high-performance numerical and scientific computing while also being effective for general-purpose programming, even web use or as a specification language.

You can download Julia from here http://julialang.org/

Clojure Programming Language --> October 29 from 1:00 to 2:00pm (d-shop on Building 9 at SAP Labs Silicon Valley)

For SAP Employees

https://jam4.sapjam.com/groups/sh2Kp26QQkHwkMPFAEqAD9/events/RoZ8dId4NGqxzWCys2hMN4

For Externals

https://www.eventbrite.com/myevent?eid=18783402663

Clojure is a dynamic programming language that targets the Java Virtual Machine (and the CLR, and JavaScript). It is designed to be a general-purpose language, combining the approachability and interactive development of a scripting language with an efficient and robust infrastructure for multithreaded programming. Clojure is a dialect of Lisp, and shares with Lisp the code-as-data philosophy and a powerful macro system.

You can download Clojure from here http://clojure.org/

Greetings,

Blag.
Development Culture.

(Defining SAP HANA (OData) with Racket)

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Wed, 23 Sep 2015 19:42:00 +0000

This post was originally posted on (Defining SAP HANA (OData) with Racket).

Racket is a full spectrum programming language that goes beyond Lisp and Scheme with dialects that support objects, types, laziness and more. And that more means Functional, Procedural, Object Oriented, Logic, Reflective and Meta.

Basically…Racket is the new name of PLT Scheme. And PLT Scheme comes from the Lisp family.

So, before we move on…I want to share an XKCD comic that brings some light about Lisp -:)

First, we need to create a Calculation View and call it “FLIGHTS_BY_CARRIER”. It will be composed of two tables, SCARR and SFLIGHT.

First, we need to create a Join object and link the table by MANDT and CARRID. From here select the following fields as output MANDT, CARRID, CARRNAME, PRICE and CURRENCY.

Then create an Aggregation object selecting the fields CARRNAME, PRICE (As Aggregated Column) and CURRENCY. Filter the CURRENCY field by ‘USD’.

Then create a Projection object and select only PRICE and CARRNAME.

On the Semantics object make sure to select “CROSS CLIENT” as the Default Client.

Now, switch to the SAP HANA Development View and create a new repository. Call it “Flights”.

Create a new “XS Engine” project and call it “Flights” as well. Link it to the “Flights” repository.

Create an empty “.xsapp” file.

Create a file called “.xsaccess” with the following code.

.xsaccess
{ "exposed" : true, "authentication" : [ { "method" : "Basic" } ] }

Finally create a file called “flights.xsodata” with the following code

flights.xodata
service { "Blag/FLIGHTS_BY_CARRIER.calculationview" as "FLIGHTS" keys generate local "Id"; }

Activate your project and launch it on your browser, you should see something like this…

The SAP HANA part is done…so we can move into the Racket part…

Racket is a very complete programming language…so no external packages are needed…

To code for Racket I use the best Racket editor “Dr. Racket” that is actually embedded in the Racket installer…so again…no need to worry -:)

Copy and paste the following code…

Racket_HANA.rkt
#lang racket (require json) (require net/base64) (require net/url) (define make-auth-header (list (string-append "Authorization: Basic " (bytes->string/utf-8 (base64-encode (string->bytes/utf-8 (string-append "SYSTEM" ":" "YourPassword"))))))) (define (get_path path params) (port->string(get-pure-port path params))) (define json (string->jsexpr (get_path (string->url "YouServer:8000/Flights/flights.xsodata/FLIGHTS?$format=json") make-auth-header))) (define results (hash-ref (hash-ref json 'd) 'results)) (define (show_info results len ctr) (cond [(or (= ctr len) (< ctr len)) (string-append (hash-ref (list-ref results ctr) 'CARRNAME) ": " (hash-ref (list-ref results 0) 'PRICE) "\n" (show_info results len (add1 ctr)))] [(> ctr len) (string-append "" "\n")])) (display (show_info results (sub1 (length results)) 0))

Racket_HANA.rkt

#lang racket
(require json)
(require net/base64)
(require net/url)

(define make-auth-header
     (list (string-append
       "Authorization: Basic "
       (bytes->string/utf-8
        (base64-encode
         (string->bytes/utf-8
          (string-append "SYSTEM" ":" "YourPassword")))))))

(define (get_path path params)
  (port->string(get-pure-port path params)))

(define json (string->jsexpr (get_path (string->url "YouServer:8000/Flights/flights.xsodata/FLIGHTS?$format=json") 
                              make-auth-header)))
(define results (hash-ref (hash-ref json 'd) 'results))

(define (show_info results len ctr)
  (cond [(or (= ctr len) (< ctr len))
         (string-append (hash-ref (list-ref results ctr) 'CARRNAME) ": "
                        (hash-ref (list-ref results 0) 'PRICE) "\n"
                        (show_info results len (add1 ctr)))]
        [(> ctr len)
         (string-append "" "\n")]))

(display (show_info results (sub1 (length results)) 0))

Now you see it…Racket is all about parenthesis -:) Anyway…press the run button and you will have this…

I have been interfacing SAP HANA OData with a lot of languages…and so far…Racket has been one of my fastest implementations…while it’s hard to get used to all these weird parenthesis…it’s a very nice and powerful language…and thing get done faster that one could imagine…

Greetings,

Blag.

Development Culture.

LED is my new Hello World - Falcon Time

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Fri, 18 Sep 2015 18:35:00 +0000

Following my tradition...here's my LED Numbers app using Falcon...I used my Julia code as a base start...and I gotta say...the code is pretty much the same...which is nice for now...but I hope to find some hidden and weird features as I learn more about Falcon -;)

Here's the source code...

LED_Numbers.fal
leds = ["0" => [" _ ","\| \| ","\|_\| "], "1" => [" ","\| ","\| "], "2" => [" _ "," _\| ","\|_ "], "3" => ["_ ","_\| ","_\| "], "4" => [" ","\|_\| "," \| "], "5" => [" _ ","\|_ "," _\| "], "6" => [" _ ","\|_ ","\|_\| "], "7" => ["_ "," \| "," \| "], "8" => [" _ ","\|_\| ","\|_\| "], "9" => [" _ ","\|_\| "," _\| "]] print("Enter a number: ") number = input() len = number.len() for i in [0:3] for j in [0:len] print(leds[number[j]][i]) end printl("") end

LED_Numbers.fal

leds =  ["0" => [" _  ","| | ","|_| "],
         "1" => ["  ","| ","| "],
         "2" => [" _  "," _| ","|_  "],
         "3" => ["_  ","_| ","_| "],
         "4" => ["    ","|_| ","  | "],
         "5" => [" _  ","|_  "," _| "],
         "6" => [" _  ","|_  ","|_| "],
         "7" => ["_   "," |  "," |  "],
         "8" => [" _  ","|_| ","|_| "],
         "9" => [" _  ","|_| "," _| "]]
   
print("Enter a number: ")
number = input()
len = number.len()
for i in [0:3]
 for j in [0:len]
  print(leds[number[j]][i])
 end
 printl("")
end

And of course...here are the pictures...

Greetings,

Blag.
Development Culture.

My first post on Falcon

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Fri, 18 Sep 2015 17:55:00 +0000

I discovered Falcon a couple of months ago...but didn't have the time to start playing with it...

Falcon is an open source, multi-paradigm programming language. While it looks like a new programming language, it's actually kind of old having it's first appearance on 2003...

Syntactically, it's pretty similar to Lua...which means is kind of similar to Go or C++...but of course it has some pretty and unique cool features -;)

For now...I just ported my Lua version of the Fibonacci Numbers...and beside the fact that Falcon doesn't use "then" and the fact that Falcon can't concatenate numbers with string (but can concatenate string with numbers)...the code is pretty much the same...

Let's see how it goes when I code my LED Numbers app -;)

Here's the code...

fibonacci.fal
function fib(num,a,b) result = "" if a > 0 and num > 1 result = result + (a+b) + " " + fib(num-1,a+b,a) elif a == 0 result = "" + a + " " + b + " " + (a+b) + " " + fib(num-1,a+b,b) end return result end print("Enter a number: ") num = int( input() ) print(fib(num,0,1))

fibonacci.fal

function fib(num,a,b)
 result = ""
 if a > 0 and num > 1
  result = result + (a+b) + " " + fib(num-1,a+b,a)
 elif a == 0
  result = "" + a + " " + b + " " + (a+b) + " " + fib(num-1,a+b,b)
 end
 return result 
end

print("Enter a number: ")
num = int( input() )
print(fib(num,0,1))

Here's the result...

Greetings,

Blag.
Development Culture.

Purely SAP HANA with Haskell

noreply@blogger.com (Alvaro "Blag" Tejada Galindo) — Thu, 17 Sep 2015 19:22:00 +0000

This post was originally posted on Purely SAP HANA with Haskell.

Haskell is a general-purpose purely functional programming language with non-strict semantics and strong static typing.

What does that means? Nothing…just that Haskell is the most pure programming language around…which means that there are not and cannot be side effects…like Haskellers like to say…”If it compiles…it will always work”…

There’s an XKCD cartoon that nicely resumes what Haskell is about -;)

Well…I will run it -:P What I love about Haskell is that it really makes you forget everything you learned before…once assigned, a variable can’t never change its value…recursion is a must…printing on the terminal is considered impure, but there’s of course a work around it…everything is a function…forget about Classes and Objects…pattern matching is your best friend…and so many more cool things -;)