The slides from my presentation about functional programming in Scala at JEEConf in Kiev, Ukraine are uploaded to Slideshare and awaiting your comments.

Thank you, thank you, Coursera, Martin Odersky and his team, Michał, Thomas, and whoever has helped me to learn so much and at long last sorted the assignment out! I could score 10 out of 10 in Week 6: Collections in the course Functional Programming Principles in Scala at Coursera.

I can finally go to bed without worrying I couldn’t finish the assignment on time! I was tearing my hair out trying to get the job finished on time and I even asked people around about additional tips as it seemed I might’ve not found the solution.

After almost a week of very intensive labours, my dear friend Michał Fijołek sent me a hint – the thread sentenceAnagrams Suggestions on the course’s discussion forum in which I found missing pieces to the puzzle! Without the hint I would certainly not have sorted it out, but fortunately I was close. When I followed the advices given in the very first email in the thread, I reorganized my code and all of a sudden the very first test run finished without any errors! I couldn’t believe my eyes. I thought they’re deceiving me.

When I submitted the code, the time the result took to show up lasted forever. The result was available after a very, very, very long 2 minutes and 10 out of 10 was the most amazing end of the day. Just a day before the final submission date I passed the tests! All of them!

Thanks Michał and Thomas Otani (who wrote the email in the golden thread)! You made my day and I’m very grateful.

On to Week 7: Lazy Evaluation.

I like simple solutions and I usually very easily adapt behaviors that reflect similar approach. I quickly learnt pattern matching as a way to destructure collections and sequences in Scala. So quickly that I almost forgot about the plain old if expression. Too bad, Jacek!

I’ve just noticed that once I got used to pattern matching in Scala I kept writing applications as follows:

It struck me when I went as far as to use pattern matching for a check of emptiness vs non-emptiness yet I didn’t want to have the list to be destructured.

Notice the last case expression with a catch-all _ wildcard. It was ridiculous to use pattern matching when the if expression was all I actually needed. That’s why I believe that pattern matching might not always be the most elegant approach and the plain, old if expression might be better.

It’s much more elegant for me. Hopefully, it’s a more idiomatic code, too. Is it?

You may be asking yourself, when do I care about the case of an empty list and don’t bother about destructuring? I’d love hearing your thoughts about it before I share mine. Go ahead and teach me a bit of Scala!

My schedule didn’t work out well for the past weeks. I simply couldn’t spare much time for a few self-learning activities and so I couldn’t submit the programming assignment for Huffman Coding (Week 4: Types and Pattern Matching) in the course Functional Programming Principles in Scala at Coursera earlier.

1,5 days later I scored the maximum – 10 out of 10, but with the penalty of 20% less a day after the due date I ultimately ended up with 6.

What the course has learnt me is more valuable than the score itself, tough. I’m getting used to Scala’s tools like Scala’s REPL and sbt, and at the end of the week at Coursera my working environment was Sublime Text 2 and a terminal that looked as follows.

I’ve got the upper window for sbt ~test, the middle for Scala REPL and finally the bottom for git. It worked so well that I have just upgraded IntelliJ IDEA to 12.1.2 in the meantime even though I promised myself to use IDEA more often.

I also submitted the question Idiomatic search of value in a list of element-value pairs in Scala at StackOverflow and got 5 points more.

I’ve been following Odersky’s Functional Programming Principles in Scala at Coursera and when I’ve been asked to tackle a programming problem I ended up with the following:

Since I’ve been writing the application in Sublime Text 2 and copying and pasting it to Scala REPL, the only result I’ve been getting were the following errors:

:load A.scala didn’t work either.

When I defined an empty trait A first so I could get passed the error, I got another.

Now, I’ve been facing two issues :( I’ve been fooled by

and spent hours googling to figure out what was wrong.

Right before I submitted a question on StackOverflow, I remembered :paste to paste an entire application so it’s compiled as a single compilation unit. That was that!

It looks I might need a bit more support from tools than what I got from Sublime Text 2 and Scala REPL as I’m simply still in my infancy of developing applications in Scala. Lesson learnt.

I can’t explain how happy I am! At long last I could score 10.00 out of 10.00 in the part Object-Oriented Sets (Week 3: Data and Abstraction) in the course Functional Programming Principles in Scala at Coursera. It took me almost 3 weeks of a very intensive mental exercise to finally make it and I’m pretty sure I wouldn’t have achieved it without the tests that were part of the assignment and many more I wrote myself.

The exercise has therefore proved to me that the idea of writing tests is the only viable approach to tackle programming assignments.

I used to think that writing standalone applications could replace tests. It had been working fine for my self-study exercises, but didn’t work for the exercises at Coursera. Since they were part of the assignment it’d have been weird not to leverage their existence that eventually led me to writing even more. I enjoyed the activity so much.

Before I could see the above result, I submitted four other solutions with the maximum score of 9.94. I used git to keep the sources under control and compare the previous submissions that also helped a lot – when I wasn’t satisfied with the results I simply checked out another version and started over.

What I found very productive was to have sbt console open with ~test. When I saved a test or a class it automatically fired up the tests and gave me a result. It was so much easier than re-executing sbt test or test in the sbt console every change.

All in all, git, ScalaTest, sbt’s ~test and many late-night hours of rewriting the code and reading the discussions on the course’s forum made the score of 10 out of 10 achievable. It was painful mental-wise, but the final result did make my day.

I’m yet to submit the other exercise Huffman Coding of Week 4: Types and Pattern Matching by Sun 28 Apr 2013 11:59 PM CEST +0200 to score high. It’s certainly not an easy task given I’ve got 2 days left. It’s gonna be tough. Wish me luck.