Add binary search

[janAkali]

I used linear_search.nim as base, so checkBinarySearch template is redundant, but could be useful in future for other implementations. I am also not sure if it is a good idea or not to check if array is sorted at the start of function; for example:

from std/algorithm import isSorted, SortOrder

func binarySearch*[T:Ordinal](arr: openArray[T], key: T): Option[Natural] {.raises: [ValueError].} =
  if not arr.isSorted(Ascending):
    raise newException(ValueError, "Array is not sorted or not in ascending order.")

[SatinWukerORIG]

The code looks very good! However, I recommend adding a recursive binary search in order to provide another alternative to people who wants to learn binary search. See https://www.geeksforgeeks.org/binary-search/

[janAkali]

I recommend adding a recursive binary search in order to provide another alternative to people who wants to learn binary search. See https://www.geeksforgeeks.org/binary-search/

Thank you for the link! I added recursive version and fixed a little inconsistency: mid.Natural->Natural(mid).

[SatinWukerORIG]

Looks great!

[ZoomRmc]

Thanks for your contribution! Please, consider the proposed changes.

[dlesnoff]

Thanks for your nice implementation!
Some more tests are required but apart from that, the implementation is great.
Please specify that you do not provide a specific element in case of duplicates.
The choice of pivot has to be explained. You use a neat trick to avoid arithmetic overflow and that particularity is non-trivial for beginners.

[dlesnoff]

I changed my mind. Let us just refer to Wikipedia for precisions on theoretical aspects, it will ever be more reviewed and better referenced as well.
Simplify the docstring as suggested, and I'll finally accept the changes.

[dlesnoff]

Run nimpretty to remove trailing whitespaces. You can wrap the arguments on one line by adding a line break after the parenthesis instead of the automatically inserted line break by nimpretty.
I will merge it immediately after.

[dlesnoff]

Nice first contribution!