Looking at the API for Tango, there's little to no usage of operator overloading. While I'm not a fan of overloading operator meanings, there are at least a few cases where it makes sense, particularly the collection classes. Sequences could overload opIndex, opSlice, opCat, and their respective variations, while maps could implement opIndex, and all container types could implement opIn and opEquals.
Is it a deliberate part of your design not to overload operators, or have you just not got around to it yet?