A design for warm fusion
Laszlo Nemeth and Simon Peyton Jones, Prc 10th International Worskhop
on the Implementation of Functional Languages (IFL'98), pp 381-394.
This is a rather old paper, and I don't have the Latex source.
However I've scanned it, and here's the result.
Here, too, is Laszlo's thesis "Catamorphism-based
program transformations for non-strict functional languages",
which gives a much more detailed exposition of warm fusion.