Arrays with Missing Hunks

Is it feasible that DArray could support distributed arrays in which pieces are missing?

For instance, say I have the following:

```
X X X
X X X X
X X
```

where each `X` represents a dense portion of an array and the blanks represent a portion which can be modeled as representing a single value throughout.

In my mind, DArray has some sort of address table and, when it does a lookup, it could note the gap and return an appropriately formatted response using the constant value.