I'll introduce some uses of Ruby in my everyday office hours. Various kind of tasks are helped by Ruby: deta processiong, scraping, excel sheet generation, Instllation ruby, etc. This is a continuation of old my talk series: Shigoto de tsukau Ruby.

In my view, the primary reason why Python has become popular in scientific computing is that Python has Numpy, a powerful tool for data processing and it serves as the basis of various libraries. As an equivalent to Numpy in Ruby, I have been developing NArray as I reported in RubyKaigi 2010. Now I am developing the new version of NArray as a library in Ruby/Numo (NUmerical MOdule). Currently Ruby/Numo contains interfaces to BLAS/LAPACK, GSL, FFTE, and Gnuplot. However, the development is far from complete and needs further effort. In this talk, I will report the progress of the Ruby/Numo project and discuss issues in scientific computing with Ruby.

TreasureData deals with huge amount of streaming data import request and saves them into our database in realtime without any lost.

New scalable system is required to process requests increasing day by day, and I decided to replace old system with rails and fluentd to new system with h2o and mruby for gateway server.

I'll introduce why h2o and mruby is good and how I optimized mruby server handler for the system. In addition, I'll talk about my patches for h2o to make it possible for mruby parallel processing/asynchronous processing. And also, I'll show benchmarks of actual product.

This talk describes how to write Lint for Ruby program.

Lint finds bugs from code automatically. So, if you can write Lint, you can reduce bugs from your code automatically.

This talk includes the following topics.

- Implementation of existing Lint such as [RuboCop](https://github.com/bbatsov/rubocop) and [Reek](https://github.com/troessner/reek).

- How to create new Lint or add a new rule to existing Lint yourself.

The Smalruby is a 2D game development library that aims to be compatible with Scratch (Scratch is most famous visual programming language: https://scratch.mit.edu/).

Reacently, programming education for kids is expanding rapidly and Scratch is ususally a first-contact programming language for them.

Some kids, good Scratchers, try to learn a text-based programming languege.

Smalruby helps to make Scratcher Rubyist!

This talk includes the following topics:

* The recent situation of programming education for kids.

* Smalruby's features.

* Smalruby inside.

WebAssembly is a state-of-the-art technology to run CPU intensive calculation on the browser. So how does it relate to Ruby? Well, for instance, you would like to use it while writing browser games, with Ruby.

In this talk, I will introduce [DXOpal](https://github.com/yhara/dxopal), a game programming framework for Opal (Ruby-to-JavaScript compiler). DXOpal takes advantage of WebAssembly for complex calculations like collision detection.