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Expand Up @@ -23,25 +23,17 @@
<h1>The Power of Crystal:<br /><span style="font-size: 80%">A language for humans and computers</span></h1>
<h2>Johannes Müller &ndash; Crystal Core Team / Manas.Tech</h2>
</hgroup>
<img src="assets/helvetic-crystal.svg" style="width: 2em; margin-top: 1em; filter: invert();" />
<img src="assets/crystal.svg" style="width: 2em; margin-top: 1em; filter: invert();" />
</section>

<section>
<h1>Agenda</h1>
<ul>
<li>Intro to Crystal</li>
<li>Comparison with Ruby</li>
<li>Combined Power</li>
<li>Learnings for Ruby devs</li>
<li>Hello World</li>
<li>Crystal primer</li>
<li>Open Source and Me</li>
</ul>
<aside class="notes">
<ul>
<li>Last point: In case you go out of this talk and feel like you never want to have anything to do with
Crystal,
there are some useful insights when looking at Ruby from a Crystal perspective which might help you become
a better Ruby programmer.
</li>
</ul>
</aside>
</section>

Expand All @@ -55,8 +47,7 @@ <h1>Agenda</h1>
<p>mastodon: <a href="https://fosstodon.org/@straightshoota">@straightshoota</a></p>

<p style="clear: right; text-align: right;">
Follow the slides<br />
<a href="https://straight-shoota.github.io/power-of-crystal/">straight-shoota.github.io/power-of-crystal</a>
<a href="https://crystal-lang.github.io/crystal-intro/">Follow the slides</a>
</p>
<hr>
<p>
Expand All @@ -65,162 +56,42 @@ <h1>Agenda</h1>

<aside class="notes">
<ul>
<li>Slide info</li>
<li>....</li>
<li>When I learned Ruby, it was the first time I fell in love with a programming language (fun)</li>
<li>Later Crystal was the second time</li>
<li>it expanded on Ruby, adding some extra flavour that I find very attractive</li>
<li>Crystal was/is still young, so lots of stuff was missing and I started contributing (stdlib and compiler)
</li>
<li>Eventually became a Core Team member</li>
<li>now working on Crystal full time. I'm principal engineer of the Crystal team at Manas, the place were
Crystal was born and continues stewardship of the project.</li>
</ul>
</aside>
</section>

<section>
<h2>Manas.Tech</h2>
<a href="https://manas.tech/"><img src="assets/manas.svg" alt="Manas" style="width: 33%; aspect-ratio: 1;"></a>

<aside class="notes">
<ul>
<li>Manas is a software agency from Argentina with an international team</li>
<li>we use lots of different technologies</li>
<li>lot of love for Ruby (on Rails)</li>
<li>Ruby has some great properties:</li>
</ul>
</aside>
</section>

<section>
<div>
<h2>Benefits of Ruby</h2>
<ul>
<li>User-friendly syntax</li>
<li>Versatile and productive</li>
<li>Simple and intuitive</li>
</ul>
</div>

<aside class="notes">
<ul>
<li>I just picked some examples, we could continue this list</li>
<li>These are a result of the creators vision.</li>
</ul>
</aside>
</section>

<section>
<div>
<p style="text-wrap: balance;">Matz (1993): <em>“What would a <strong>really good</strong> programming language look
like?”</em></p>

<p class="fragment">
<code class="language-crystal">puts <span class="hljs-string">"Hello, Ruby!"</span></code>
</p>
</div>
<div class="fragment">
<hr>
<p style="text-wrap: balance;">Ary (2011): <em>“What if Matz's good programming language could
somehow statically compile?”</em></p>
</div>

<p class="fragment">
<code class="language-crystal">puts <span class="hljs-string">"Hello, Crystal!"</span></code>
</p>

<aside class="notes">
<ul>
<li>Journey back in time, to a dude in Japan. Yukihiro Matsumoto</li>
<li>Matz (father of Ruby) realized his vision of “a good” programming language. Many people agree on
that and found it useful</li>
<li>Hello Ruby</li>
<li>approval rate is probably pretty high in this room here</li>
<li>Ary (father of Crystal) wondered “what if we could somehow
statically compile Ruby?”
</li>
<li>Hello Crystal</li>
<li>Started as experiment. Compiler originally written in Ruby. Grew into language and ecosystem.</li>
<li>Matz is grandfather of Crystal</li>
<li>The reasons to change anything about Ruby is that it has some downsides</li>
</ul>
<a href="https://manas.tech/blog/2016/04/01/the-story-behind-crystal/">The story behind Crystal</a>
<a href="https://www.youtube.com/watch?v=KbFHbkY27no">Yukihiro "Matz" Matsumoto - Pushing boundaries | Crystal
1.0 Conference</a>
</aside>
</section>

<section>
<div>
<h2>Ruby Drawbacks</h2>
<ul>
<li>Type checking</li>
<li>Raw performance</li>
<li>Software distribution</li>
<li>Concurrency</li>
</ul>
</div>

<aside class="notes">
<ul>
<li>type checking is possible via RBS or Sorbet. But those are bolted on and limited; challenging with
compatibility and coherence of the ecosystem.</li>
<li>Ruby 3 and JIT increased performance significantly.<br>But dynamic nature puts it still
on a different level of efficiency compared to native code.</li>
<li>Ruby requires the language runtime. It's hard to distribute software to non-developers.</li>
<li>Writing concurren software can be an adventure</li>
<li>Some examples. I'm sure there are more issues with Ruby.</li>
<li>A programming language is always a set of features and compromises</li>
</ul>
</aside>
</section>

<section>
<h2>Crystal's answers</h2>
<h2>Benefits of Crystal</h2>
<ul>
<li>Goodies from Ruby's lineage</li>
<li>Inherited a lot of goodies from Ruby</li>
<li>User-friendly syntax</li>
<li>Versatile and productive</li>
<li>Simple and intuitive</li>
<li>Static typing with type inference</li>
<li>Compiles to highly efficient machine code</li>
<li>Strong, intuitive concurrency model</li>
</ul>

<aside class="notes">
<p>Crystal takes the best from Ruby and adds some more</p>
<p>moves more to the static without loosing to much dynamic feel</p>
<p>...</p>
<p>fresh approach to the underlying ideas of Ruby as a new but similar language.</p>
<p>somewhat similar to alternative Ruby implementations (JRuby, Rubinious, or mruby), but it goes a step
further</p>
<p>still very similar and largely identical to Ruby.</p>
<p>You can leverage your Ruby knowledge for Crystal.</p>
<p>Lets explore some commonalities and differences</p>
</aside>
</section>

<section>
<h2>Syntax</h2>
<div>
<pre><code class="language-crystal"># src/hello.crb

# Polyglot program that is valid Ruby and Crystal
# and can tell one from the other

LANGUAGE = Array.to_s == "Array(T)" ? "Crystal" : "Ruby"

puts "Hello, #{LANGUAGE}!"</code></pre>
<pre class="fragment"><code class="language-console" style="white-space: pre-wrap;">$ ruby src/hello.crb
Hello, Ruby!
<h2>Install</h2>
</section>

$ crystal src/hello.crb
<section>
<h2>Hello, World</h2>
<div>
<pre><code class="language-crystal"># src/hello.cr
puts "Hello, Crystal!"</code></pre>
<pre class="fragment"><code class="language-console" style="white-space: pre-wrap;">$ crystal src/hello.cr
Hello, Crystal!
</code></pre>
</div>
<aside class="notes">
<p>extremely similar</p>
<p>Detection uses a trick: `Array.to_s` returns `"Array(T)"` in Crystal. The `T` is a generic type argument and we'll come to that
later</p>
</aside>
</section>

<section>
Expand All @@ -242,7 +113,6 @@ <h2>Batteries included</h2>

<aside class="notes">
<ul>
<li>This could be a Ruby program, right? Just using some `HTTP` library</li>
<li><code>http/server</code> is part of Crystal's standard library</li>
<li>Crystal comes with a lot of useful tools out of the box</li>
<li>requests are handled in individual fibers, enabling concurrency (not that useful if you just print hello Crystalm but imagine bigger)</li>
Expand Down Expand Up @@ -313,11 +183,9 @@ <h2>Static Typing</h2>

<aside class="notes">
<ul>
<li>Ruby has a similar error, but it only appears when the code executes</li>
<li>In Crystal you get the error at compile time</li>
<li>Excludes a whole class of common errors in Ruby (like
<code>NoMethodError: undefined method for nil:NilClass</code>)</li>
<li>in Ruby you need to do extensive testing to lock this down</li>
<li>In Crystal you get an error at compile time (unlike in a dynamically typed language where it would be a runtime error)</li>
<li>Excludes a whole class of common errors like null pointer exceptions</li>
<li>in dynamic languages you need extensive testing to lock this down</li>
</ul>
</aside>
</section>
Expand Down Expand Up @@ -416,7 +284,7 @@ <h2>Compilation</h2>
<li>cross compilation is also possible</li>
<li>LLVM is used for codegen by other languages as well (Rust for example, or clang)</li>
<li>optimizations are sometimes ridiculously good</li>
<li>All code needs to be fixed at compile time. There’s no `eval` or `send`. Cannot modify program at runtime. Core feature of Ruby's dynamicness.</li>
<li>All code needs to be fixed at compile time.</li>
</ul>
</aside>
</section>
Expand Down Expand Up @@ -590,118 +458,24 @@ <h2>Dependencies</h2>
</section>

<section>
<h2>Ruby with Crystal</h2>
<p>Embed Crystal code directly in Ruby</p>

<pre><code class="language-ruby" data-trim>require 'crystalruby'

module MyTestModule
# The below method will be replaced by a compiled Crystal version
# linked using FFI.
crystalize [a: :int, b: :int] => :int
def add(a, b)
a + b
end
end

# This method is run in Crystal, not Ruby!
MyTestModule.add(1, 2) # => 3
</code></pre>
<a href="https://github.com/wouterken/crystalruby">wouterken/crystalruby</a>
</section>

<section>
<h2>Crystal with Ruby</h2>
<p>Embed an mruby interpreter in Crystal</p>

<pre><code class="language-crystal" data-trim>require "anyolite"

Anyolite::RbInterpreter.create do |rb|
rb.execute_script_line(%[puts "Hello from Ruby"])
end
</code></pre>
<a href="https://github.com/Anyolite/anyolite">Anyolite/anyolite</a>
</section>

<section>
<h2>Combine Ruby &amp; Crystal</h2>
<ul>
<li>delegate performance-critical workloads</li>
<li>background job processing</li>
<li>service backend</li>
<li><a href="https://crystal-lang.org/reference/tutorials/basics/index.html">Language introduction tutorial</a></li>
<li><a href="https://exercism.org/tracks/Crystal">Excercism Track</a></li>
</ul>

<aside class="notes">
<p>Other forms of collaboration</p>
<p>Crystal is as good as other alternatives (Rust, Go, Zig, C ...)</p>
<p>let Crystal handle performance-critical jobs</p>
<p>bg-jobs via sidekiq adapter etc.</p>
<p>e.g. websocket server, streaming server</p>
</aside>
</section>

<section>
<h2>Learnings for Rubyists</h2>

<p>avoiding repeat calculations</p>
<pre><code class="language-crystal">abstract def bar : String | Nil
abstract def foo(arg : String)
</code></pre>
<pre><code class="language-crystal" data-trim>if bar
foo(bar) # Error: expected argument #1 to 'foo'
# to be String, not (String | Nil)
end
</code></pre>
<pre class="fragment"><code class="language-crystal" data-trim>
if b = bar
foo(b)
end
</code></pre>

<aside class="notes">
<p><em>How Crystal makes you a better Ruby developer</em></p>
</aside>
</section>

<section>
<h2>Learnings for Rubyists</h2>
<pre><code class="language-ruby">
{
"action" => "foo",
"credentials" => {
"id" => "abc",
"secret" => "psst"
},
"value" => 12,
}
</code></pre>
<aside class="notes">
<ul>
<li>In Ruby there's often a tendency to put semi-structured data into shapeless hashes</li>
<li>This is problematic in Crystal due to static typing</li>
<li>explicitly structured types are more efficient, descriptive</li>
<li>for static key names, use a type</li>
</ul>
</aside>
<h1>Open Source</h1>
</section>

<section>
<ul>
<li><a href="https://crystal-lang.org/reference/1.12/tutorials/basics/index.html">Language introduction tutorial</a></li>
<li><a href="https://www.crystalforrubyists.com/">Crystal for Rubyists</a></li>
<li><a href="https://crystal-lang.org/reference/1.12/crystal_for_rubyists/index.html">Crystal for Rubyists</a></li>
<li><a href="https://github.com/crystal-lang/crystal/wiki/Crystal-Shards-for-Ruby-Gems">Crystal-Shards-for-Ruby-Gems</a></li>
<li><a href="https://exercism.org/tracks/Crystal">Excercism Track</a></li>
</ul>
<h1>Contributing to Open Source</h1>
</section>

<section>
<h2>Conclusion</h2>
<ul>
<li>Crystal can be a useful asset in your toolbox</li>
<li>Enhance your Ruby project</li>
<li>Knowing Ruby makes you almost a Crystal developer</li>
<li>Knowing Crystal makes you a better Ruby developer</li>
</ul>
</section>

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