22 Oct
2002
22 Oct
'02
8:36 a.m.
The problem is that the G-machine optimizes away some of the updates which make sure that the heap is always in a consistent state in a pure graph-reduction system.
A pure G-machine updates all redexes, but the STG-machine only updates /shared/ redexes, yes?
It's a while since I looked at it but, IIRC, a naive graph reducer can update the same redex multiple times while the G-machine tries to update it just once. -- Alastair