new exercise bowling

[abo64]

No description provided.

[rbasso]

Thanks for implementing one more exercise, @abo64!

Except for the comment in the stub solution, everything seems great. 👍

[rbasso]

Since #302 , the stub solutions do not have comments anymore.

We did this because most people where submitting solutions without removing them, and HINTS.md seemed the most appropriate place, so people will have to get used to reading the README.md file in case of trouble.

Also, to mark data types that need to be changed by the user, we are using Dummy and adding instructions in HINTS.md. Take a look at the exercises forth, custom-set and binary-search-tree that we fixed; all of them now have a HINTS.md and a data type to be implemented.

We are trying to make the stub solutions allow compiling and running the tests when that doesn't ruin the exercise, so it would be nice if this exercise could allow that from the start #421.

[abo64]

I appreciate your continuous efforts to improve the exercises!
It makes it somewhat harder for contributors, but the end result is worth it.

I considered to change bowlingStart to empty but decided to keep the more telling name. Hope that's ok with you.

btw perhaps you can do the squashing this time to avoid the mess I created last time? :-)

[rbasso]

It makes it somewhat harder for contributors, but the end result is worth it.

Sorry for that! We should definitely write instructions on how to implement an exercise to make things easier for contributors.

The fact is that until now we didn't standardized a format for the exercises, because we are still evolving the infrastructure and some of the exercises do not fit in anything.

An alternative would be to avoid standardization, but with more than 70 exercises it is really hard to keep things updated and manageable.