uwescience/datalogcompiler — pull request #99 by 7andrew7 (2014-01-21 00:18:41+00:00)
Title: Implement a variant of proposal #1 for stateful apply in Myrial

This PR adds support for stateful apply by adding a USING clause to the existing bag comprehension. For example:

```
out = [FROM X EMIT _sum/_count AS _avg USING 0: _count + 1 AS _count, 0: salary + _sum AS _sum];
```

I like this better than the proposal because it makes it clear that the state variables are not embedded in a particular column expression. Rather, the state variables are free-floating and can be accessed from any column. This approach also happens to be easier to implement.

comments?