On 22/04/2013, at 12:23 , "Edward Z. Yang"
I've got a solution for this problem and it will form the basis of Repa 4, which I'm hoping to finish a paper about for the upcoming Haskell Symposium.
Sounds great! You should forward me a preprint when you have something in presentable shape. I suppose before then, I should look at repa-head/repa-stream to figure out what the details are?
The basic approach is already described in: Automatic Transformation of Series Expressions into Loops Richard Waters, TOPLAS 1991 The Anatomy of a Loop Olin Shivers, ICFP 2005 The contribution of the HS paper is planning to be: 1) How to extend the approach to the combinators we need for DPH 2) How to package it nicely into a Haskell library. I'm still working on the above... Ben.