back

Other collections with illustration

2. Marks management with Sets and Maps

let s1 = set ["john";"kate";"bill"];;
let s2 = set ["kate";"sam";"amy"];;
let (&&), (||) = Set.intersect, Set.union;; // overloadind
s1 && s2, s1 || s2;;

let marks1 = Map [("bill",12);("amy",18);("john",15);("kate",16)];;
marks1 |> Map.find "bill";;
marks1 |> Map.values |> Seq.sort;;
let marks2 = Map [("bill",15);("amy",11);("john",5);("kate",19)];;
let marks n = 
    let m1 = marks1 |> Map.find n |> fun m ->("PF",m)
    let m2 = marks2 |> Map.find n |> fun m ->("UML",m)
    [m1;m2];;
marks "bill"

• Sets are similar to lists except they don't have duplicate elements and ordering is omitted. They have other operators such as union, intersection, difference, etc.
• Maps are sets of pairs (key,value) and can encode a function by the way of data that can be changed.

As an exercise, how to define the functions used in the preceding examples ?