Why std.algorithm.sort can't be applied to char[]?

[hane via Digitalmars-d-learn]

and is there any way to sort char array with algorithm.sort?
---
import std.algorithm;
import std.range;

void main()
{
   int[] arr = [5, 3, 7];
   sort(arr); // OK

   char[] arr2 = ['z', 'g', 'c'];
   sort(arr2); // error
   sort!q{ a[0] > b[0] }(zip(arr, arr2)); // error
}
---
I don't know what's difference between int[] and char[] in D, but 
it's very unnatural.