forwardable

config.ru

require 'sinatra/base'
require 'forwardable'

class I18n
  def self.t(s); "I18n.t(#{s})"; end
  def self.l(s); "I18n.l(#{s})"; end
end

class App < Sinatra::Base
  extend Forwardable
  helpers do
    def_delegators I18n, :t, :l
  end

  get '/t/:s' do
    t(params[:s])
  end
  get '/l/:s' do
    l(params[:s])
  end
end

run App.new

# Usage:
# $ rackup
#
# $ curl http://localhost:9292/t/hogehoge #=>