00195.rb

%w[yaks morpher ast].each do |lib|
  $:.unshift("/home/arne/github/#{lib}/lib")
  $:.unshift("/home/arne/github/#{lib}/#{lib}/lib")
  require lib
end

require 'pp'

r=Yaks::Resource.new(
  attributes: {name: "Plain grass", type: "grass"},
  links: [
    Yaks::Resource::Link.new(rel: :self, uri: 'http://api.example.com/plants/7/plain_grass')
  ]
)

include Morpher::NodeHelpers

ast = s(:block,
        s(:dump_attribute_hash, s(:param, Yaks::Resource)),
        s(:key_fetch, :attributes))

evaluator = Morpher.compile(ast)

result = evaluator.call(r) # => {:name=>"Plain grass", :type=>"grass"}

# So far so good, but now I need to transform r.links into a specific
# format, and put it under the :_links key. How would I do that with
# Morpher?

link_hash = r.links.reduce({}) do |hsh, l|
  hsh[l.rel] = { href: l.uri }
end

result = result.merge(_links: link_hash)

pp result
# >> {:name=>"Plain grass",
# >>  :type=>"grass",
# >>  :_links=>{:href=>"http://api.example.com/plants/7/plain_grass"}}