Why can't I initialize storage array right away?

Question

Why can't I initialize storage arrays when declaring them rather than initializing them in function or constructor?

example: this does not work, it amounts to [0, 0, 0, 0]

contract Example {
   uint256[4] array = [1, 2, 3, 4];
   ...
   constructor () {}
}

this does work

contract Example {
   uint256[4] array;
   ...
   constructor () {
      array[0] = [1];
      array[1] = [2];
      ...
   }
}

Answer 1

You can initialize the storage array like state variable.

Your code works!

To see the values inside your array you can add this function in your contract:

function getArray(uint index) external view returns(uint256){
       return array[index];
}

Now, you must to compile the contract, and put the position index of array that you want the value and it will return the value.

UPDATED ANSWER: For initialize state variable, you must use the following statement:

uint256[4] array = [[VALUE_INDEX_0], [VALUE_INDEX_1], [VALUE_INDEX_2], [VALUE_INDEX_3]];

You must to use only the statement above if you want to initialize and array like state variable. But in a function or constructor you can the statement above or you can access at single index of array and pass it the value. Ex.:

array[0] = 10;
array[1] = 20;

Answer 2

Your code works perfectly fine!
I added a view function getArray() to get your storage array.

contract Example {
   uint256[4] array = [1, 2, 3, 4];

   constructor () {}

    function getArray() external view returns(uint256[4] memory) {
       return array;
   }
}