Improving the lazy Krivine machine

Krivine presents the K machine, which produces weak head normal form results. Sestoft introduces several call-by-need variants of the K machine that implement result sharing via pushing update markers on the stack in a way similar to the TIM and the STG machine. When a sequence of consecutive markers appears on the stack, all but the first cause redundant updates. Improvements related to these sequences have dealt with either the consumption of the markers or the removal of the markers once they appear. Here we present an improvement that eliminates the production of marker sequences of length greater than one. This improvement results in the C machine, a more space and time efficient variant of K. We then apply the classic optimization of short-circuiting operand variable dereferences to create the call-by-need S machine. Finally, we combine the two improvements in the CS machine. On our benchmarks this machine uses half the stack space, performs one quarter as many updates, and exec...

• Type: Journal
• Year: 2007
• Where: LISP
• Authors: Daniel P. Friedman, Abdulaziz Ghuloum, Jeremy G. Siek, Onnie Lynn Winebarger
• Keywords: Head Normal Form, LISP 2007, Machine, Markers