Raamwerk

A toy proof of concept Ruby framework based on continuations.

Usage: gem install sinatra ruby arcchallenge.rb

The solution to the arc challenge:

page '/' do
  form do
    msg = input()
    submit do
      link("Click me"){ puts "You said #{msg}" }
    end
  end
end

As you can see you can use normal lexically scoped variables for inputs. This is an improvement over Arc which does not provide an abstraction over form input, you have to use string keys into request parameters to get form input.

A counter with links to increase and decrease the count:

def counter(i)
  puts "the counter is #{i}"
  link("increase") { counter(i+1) }
  link("decrease") { counter(i-1) }
end

page '/' do
  counter(0)
end

A todolist application looks like this:

$todo = []

def todo
  tag(:ul) do
    $todo.each do |x| 
      tag(:li){puts x; link("delete"){ $todo.delete(x); todo }}
    end
  end
  
  form do
    t = input()
    submit { $todo << t; todo }
  end
end

page '/' do
  todo
end

This displays a list of todo items with delete links, and a form to add an item.