node-http-fp.js

const http = require('http');

// Swagger-like API description
const api = {
  '/users': {
    'get': {
      'parameters': {
        'role': {
          'in': 'query'
        },
        'session_id': {
          'in': 'cookies'
        }
      },
      'x-handler': 'getUsers'
    }
  }
};

function getUsers(role, session_id) {
  return checkSession(session_id)
    .then(getUserByRole(role));
}

/**
 * @param {Object} req node req object
 * @return {Array} params
 */
function prepareParamsBasedOnSchema(req) {
  // processing request, including all possible HTTP cases
}

function getHandlerForRequest(req) {
  // retrieving handler from current req based on schema
}

/**
 * @param res node res object
 * @returns {function()}
 */
function formResponseBasedOnSchema(res) {
  return (result) => {
    // Filling headers according to schema
    // Sending result
  }
}

function errorHandler(res) {
  return (error) => {
    // log error and send some response
  }
}

http.createServer((req, res) => {
  const params = prepareParamsBasedOnSchema(req);
  const handler = getHandlerForRequest(req);
  handler.apply(null, params)
    .then(formResponseBasedOnSchema(res))
    .catch(errorHandler(res));
});