Code Dojo 1 - F# Implementation of Binary Search

fsbsearch.fsx

module Algorithms = 
    let binary_search list value =
        let rec impl(list: 'a list) (value :'a) (hi: int) (low:int)  =
            let index = (hi + low) / 2
            match compare value (list.Item(index)) with
            | 0  -> Some(index)
            | 1 -> impl list value hi index
            | -1 ->  impl list value index low
            | _ -> None
        match list with
        | [] -> None
        | _ -> impl list value (List.length list) 0