Calling OpenAI API from Crystal Language

If you want to use OpenAI API from Crystal Language, you can use the following code. (Note that you need a paid API KEY to call OpenAI API.) Make sure to set the environment variable so that ENV["OPENAI_ACCESS_TOKEN"] works.

require "option_parser"
require "http/client"
require "json"

data = {
  "model"       => "text-davinci-003",
  "prompt"      => "Hi!",
  "max_tokens"  => 10,
  "temperature" => 0,
}

OptionParser.parse do |parser|
  parser.on("-m INT", "--max-tokens INT") { |v| data["max_tokens"] = v.to_i }
end

data["prompt"] = ARGV.join(" ")

url = "https://api.openai.com/v1/completions"
api_key = ENV["OPENAI_ACCESS_TOKEN"]
headers = HTTP::Headers{
  "Authorization" => "Bearer #{api_key}",
  "Content-Type"  => "application/json",
}
response = HTTP::Client.post(url, body: data.to_json, headers: headers)

if response.status.success?
  response_data = JSON.parse(response.body)
  puts response_data["choices"][0]["text"]
else
  puts "Error: #{response.status_code} #{response.status}"
end

How to use?

crystal run file_name.cr -- Are you fine?
crystal run file_name.cr -- -m 20 Are you fine?

Or, after build,

executable_file Are you fine?
executable_file -m 20 Are you fine?

Have a nice day!