Why tthis exercise dont complie in typescript?

It could be applied with either functions, but arrow functions always lead to cleaner code. In this solution, the num parameter was changed to length so he can just include the parameter as the length of the array instead of doing this {length: num}. Leads to cleaner code. the underscore at (_, i) basically a placeholder for the value since we don't really need a specific value from an array here.

nice

Thanks for the explanation

Why that code only work using the structure: "countSheep = length =>"?

I like this solution

I have learned through research from what I saw in this answer

Very complicated in my opinion, but is valid

Not a kata issue, your function should handle that too.