• Regular Expressions
• CLI
• Grep
• Binary Trees
• Graphs
• Recursion

See README in regex

See README in cli.

See README in grep

See README in binary-trees.

See README in graphs.

See README in recursion.

Using the following template, implement the functions in the relevant file:

function template(list) {
  if (isEmpty(list)) {
    return _____;
  }

  let [first, rest] = unprepend(list);

  return _____;
}

Use this same template to implement foldl and foldr. These are higher-level functions called fold (fold left and fold right, respectively). In JavaScript, reduce is a left fold and reduceRight is a right fold.

Re-implement the functions as a single call to foldl and as a single call to foldr. Some functions are easier to implement using one pattern rather than the other. Why?

Every function can be modified to work with arrays, too. You will find it easier to use left fold with append and unappend, though.

See A tutorial on the universality and expressiveness of fold.