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The thoughts of Wes Oldenbeuving

Adventures in REIA land

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One of my current interests is the new Reia programming language, created by Tony Arcieri. The wiki contains most of the documentation, but but besides a simple “Hello, World!” and Fibonacci implementation, there is not much working code. Reia is a work in progress, so that makes sense.

Philipp Pirozhkov created Ryan, a web framework built on top of Reia and YAWS. For reasons I have yet to figure out, it does not want to build on my machine. At least there’s more code to look at to learn the language. Ryan also has a RSpec-like syntax for writing tests, which look interesting.

Starting with web development might be a bit too ambitious for me. I actually managed to mess up a simple “Hello, world!” example, so I’m starting slow. Note to self: methods in Reia have parentheses. It’s not Ruby, where you can omit them.

Wrong hello world:

puts "Hello, world!"

Proper hello world:

puts("Hello, world!")

Sincy my brain still thinks in Ruby, let’s start with a simple bit of Ruby code and convert it to Reia.

First, the Ruby code:

[1,2,3].each { |n| puts n }

This prints out three lines with 1, 2 and 3 on them. Now the same code in Reia:

[1,2,3].each { |n| puts(n.to_s()) }

The two obvious differences:

  1. All method calls need their parentheses. So use “puts(‘String’)” instead of “puts ‘String’”.
  2. The int has to be explicitly cast to a String.

Just like Ruby, Reia has multiple ways to write this code. Another Ruby-esque way to write it is by using the ‘do’ block notation instead of curly braces:

[1,2,3].each do |n|

Notice the puts() is indented and there is no “end”: that is the Python-style indentation at work. A third way to write the code is by (ab)using List Comprehensions:

[puts(x.to_s()) | x in [1,2,3]]

This is the strangest form for me, since Ruby does not have something similar. The way I interpret it is by reading from right to left: for each x in [1,2,3], do the puts thingy left of the pipe.