Slice literal assignment

[liamoc]

The following code

a[5..8] = [1,2,3]

Compiles to

(function(){
  a.slice(5, 8 + 1) = [1, 2, 3];
})();

I suggest it should compile to:

(function(){
    a.splice.apply(a,[1,3].concat([1,2,3]));
    return a;
})();          

The main problem with this approach is simply that the return value of that expression is what is removed not the new array, which would fit better with assignment semantics, hence the return statement.

[jashkenas]

Very nice idea. Splice literal to go with the slice literal. It can't be a "return", but I think we can do it with the JS comma operator.

(a.splice.apply(a,[1,3].concat([1,2,3])), a)

[liamoc]

Sounds good.

[jashkenas]

Splice literals are now on master. Your first example:

a[5..8] = [1,2,3]

Compiles to:

a.splice.apply(a, [5, 8 - 5 + 1].concat([1, 2, 3]));

You can use inclusive or exclusive ranges, as usual. We actually don't need to worry about the return value, because splices modify the array in place, and it's an AssignNode that's doing the compilation, suppressing the actual, y'know, assignment.

Closing the ticket.