Beyond Ruby

Metorex runs Ruby, and it has a few features MRI does not. Each sample below runs under Metorex and prints the output shown. Under MRI 4.0.6 each one stops at its first line with a NoMethodError.

Assertions#

assert, assert_equal, and assert_raises are available in every program, with no library to require. A failed assertion raises a RuntimeError naming what was expected and what came instead.

assert(3.between?(1, 5))
assert_equal(4, 2 + 2)
assert_raises { Integer("four") }

begin
  assert_equal(5, [2, 2].sum)
rescue RuntimeError => failure
  puts failure.message
end

Expected 5, got 4

Finding and running test files#

metorex --test DIR runs each file under DIR named *_test.rb, test_*.rb, or *_spec.rb, reports each one as ok or FAIL with the error that stopped it, and exits with status 1 when one fails. A test file is a program that uses the assertions above.

metorex --test test

RSpec with no gems#

Rex, the spec framework built into Metorex, runs suites written for RSpec 3.13 with metorex spec, and loads the first time a program names RSpec. metorex spec --coverage reports the lines and branches that ran, counted by the interpreter.

Code as objects#

parse turns source text into the syntax tree nodes the interpreter runs, and body, called on the method get_source returns, answers that method's statements as the same nodes. Each node is a hash with a "type" key. Code as objects goes through them.

def grouped(node)
  case node["type"]
  when "BinaryOp" then "(#{grouped(node["left"])} #{node["op"]} #{grouped(node["right"])})"
  when "Grouped" then grouped(node["expression"])
  when "IntLiteral" then node["value"].to_s
  when "Identifier" then node["name"]
  end
end

puts grouped(parse("rate * hours + 40").first)
puts grouped(parse("rate * (hours + 40)").first)

((rate * hours) + 40)
(rate * (hours + 40))

Listed in the README, not built yet#

The metorex README lists these, and Metorex does not have them yet:

• Traits. A module included in a class is a Ruby module and nothing more.
• Optional static typing and type inference.
• The Deque, PriorityQueue, and TreeMap collections.
• Channels, async and await, and atomics.
• MessagePack serialization.
• A JIT compiler, a language server, a debugger of its own, and a linter or formatter.

The samples on this page are tests/_examples/site/beyond_assertions.rb and beyond_parse.rb in the metorex repository, where the test suite checks their output.