miniMax Algorithm in Elm - Tests - next move wins for row 2

Scorer.elm

module Scorer exposing (..)

import Array exposing (fromList, get, set)

-- below won't work, you can't do this in elm.  You can't have two statements in the in of a let like this
nextBestMove : List Char -> Int
nextBestMove gameNode =
    let
        cells =
            fromList gameNode
    in
        set 2 'X' cells
        if ((get 0 cells == get 1 cells) && (get 1 cells == get 2 cells)) then 2 else 0

        set 5 'X' cells
        if ((get 3 cells == get 4 cells) && (get 4 cells == get 5 cells)) then 5 else 0
        
        
-- this also does not work
nextBestMove : List Char -> Int
nextBestMove gameNode =
    let
        cells =
            fromList gameNode
        set 2 'X' cells
        set 5 'X' cells
    in
        if ((get 0 cells == get 1 cells) && (get 1 cells == get 2 cells)) then 2 else 0
        if ((get 3 cells == get 4 cells) && (get 4 cells == get 5 cells)) then 5 else 0
        
{--|
  Error:
    I ran into something unexpected when parsing your code!

13|         if ((get 0 cells == get 1 cells) && (get 1 cells == get 2 cells)) then 2 else 0
            ^
I am looking for one of the following things:

    end of input
    whitespace

--}

-- I then changed it to:
nextBestMove : List Char -> Int
nextBestMove gameNode =
    let
        cells =
            fromList gameNode
        set 2 'X' cells
        set 5 'X' cells
    in
        if ((get 0 cells == get 1 cells) && (get 1 cells == get 2 cells)) then 2
        else if ((get 3 cells == get 4 cells) && (get 4 cells == get 5 cells)) then 5 else 0
{--|
  Error: 
  It looks like the keyword `in` is being used as a variable.

14|     in
          ^
Rename it to something else.
--}

ScorerSpec.elm

it "next move wins for row 2" <|
    let
        gameNode =
            [ empty, empty, empty, markerX, markerX, empty, empty, empty, empty ]

        cellFifthIndex =
            5

        nextMove =
            Scorer.nextBestMove gameNode
    in
    expect nextMove to equal cellFifthIndex

ScorerWorking.elm

{--| 
The problem was this is an ML language so you can't 
just make statements such as populating a value in an array
and call it day.  An ML language always returns a reference to something either another function, another type
etc.  In this case calling set on the array to set a value returns a new array.  I wasn't doing anything with the
returned array and trying to check logic on the original array in the `in` (body) of my function

Here's how I changed it to work now below
--}

nextBestMove gameNode =
    let
        cells =
            fromList gameNode

        nextGameState1 =
            set 2 'X' cells

        nextGameState2 =
            set 5 'X' cells
    in
    if (get 0 nextGameState1 == get 1 nextGameState1) && (get 1 nextGameState1 == get 2 nextGameState1) then
        2
    else if (get 3 nextGameState2 == get 4 nextGameState2) && (get 4 nextGameState2 == get 5 nextGameState2) then
        5
    else
        0