Q:

Dart List negative indexing does not work

Dart's List Structure doesn't seem to support negative indexing. What is the reasoning behind this? Every other language I have ever used supports this. Why did dart decide to exclude such a basic construct?
The following code -
void main() {
    List<String> x = ["foo", "bar"];
    print(x[-1]);
}

Produces - 
Uncaught exception:
RangeError (index): Index out of range: index must not be negative: -1

A:

Dart does not support negative indexes.
To access elements relative to the end, you can calculate the index using
print(x[x.length - 1])

You can create a feature request in https://github.com/dart-lang/sdk to get feedback from the language designers.

