Question

Create a F# Function.
Function Signature: zip L1 L2

The function zip combines the elements of two lists pairwise, resulting in a list of tuples, where the first tuple in the list contains the first element of L1 as the first element, and the first element of L2 as the second element

// // zip L1 L2
// // Zip two lists
// // Returns list of tuples
// // Examples:
// zip [] [] => []
// zip [1] [1] => [(1, 1)]
// zip [1; 2; 40] [3; 56; 6] => [(1, 3); (2, 56); (40, 6)]
// zip [1; 2; 3] ['a'; 'b'; 'c'] => [(1, 'a'); (2, 'b'); (3, 'c')]

Answer 1

Code: if inbuilt zip function is not to be used and need to make a zip function

let rec zip(list1:'list1 list, list2:'list2 list) : list<'list1 * 'list2> =
    // stoping condition for recursive call
    if List.length list1 = 1 then [List.head list1 , List.head list2]
    // continue the recursive call if the length > 1
    else (List.head list1, List.head list2) :: zip (List.tail list1 , List.tail list2)
  

let list1 = [1; 2; 3]
let list2 = ['a'; 'b'; 'c']
// if both the list are empty
if list1.IsEmpty then
    let zippedlist = []
    printf "%A, %A => %A\n" list1 list2 zippedlist
//if there is some content  in the list
else 
    let zippedlist = zip(list1, list2)
    printf "%A, %A => %A\n" list1 list2 zippedlist

Try the code for different values of list1 and list2

Code;: if inbuilt zip function can be used

let zip list1 list2 = 
    List.zip list1 list2
  

let list1 = [1; 2; 3]
let list2 = ['a'; 'b'; 'c']
// if both the list are empty
if list1.IsEmpty then
    let zippedlist = []
    printf "%A, %A => %A\n" list1 list2 zippedlist
//if there is some content  in the list
else 
    let zippedlist = zip list1 list2
    printf "%A, %A => %A\n" list1 list2 zippedlist

Output:

Explaination:

Firstly check if the list has some contents or not if no content i.e if list.IsEmpty = true then we can print the empty list else we go to the zip function

Zip function is a recursive function which every time takes element at the Head position of both the list and insert it as a tuple in the resulting list