Your challenge is to implement fold in the language of your choice.

fold is a higher order function that takes

• a sequence of type A
• a "starting" value of type B
• a function (A, B) -> B

and returns a B. E.g., the sum of an array is a special case of fold, where

• the sequence is an array of numbers
• the starting value is 0
• the function is +

You can find more information on Wikipedia.

Fork this repository.

Implement fold in any language of your choice. Don't directly use the fold that is already part of your language (see the list on Wikipedia).

Send us a link to your fork within 1 week of being invited to participate on this challenge.

Aim to use about 1 hour of time on the solution, don't use more than 2 hours. We give roughly equal weight to the each of the following:

• Documentation
• Packaging
• Testing
• Readability of code
• Correctness of implementation
• Performance
• Generality
• Correntness of types (if applicable)

Please don't stress if your solution isn't perfect. With a timebox of at most 2 hours, you most likely won't be able to check all the boxes above. This challenge is intended as an exercise in tradeoffs. We want to understand how you view the overall value and lifecycle of software.