old_contents: import R from 'ramda';
  
  // a -> b -> b
  const truncate = R.compose(
    R.join(''),
    R.append('...'),
    R.head,
    R.splitEvery
  );
  
  export default truncate;
  
new_contents: import R from 'ramda';
  import curry from './util/curry.js';
  import compose from './util/compose.js';
  
  // a -> b -> b
  const truncate = curry(function(a, b) {
    return compose(
      R.join(''),
      R.append('...'),
      R.head,
      R.splitEvery(a)
    )(b);
  });
  
  export default truncate;
  
subject: Refactor truncate function to use custom compose/curry function