post_hello.rb

# post_hello.rb
require 'rubygems'
require 'sinatra'

get '/' do
  <<-form
  <h1>Name to say hi!</h1>
  <form method="post">
    <input type="text" name="name">
    <input type="submit" value="send">
  </form>
  form
end

post '/' do
  "Hi #{params[:name]}"
end