,
Francesco Magliocca
,
Loïc Peyrot
,
Claudio Sacerdoti Coen
Creative Commons Attribution 4.0 International license
Skeletal call-by-need is an optimization of call-by-need evaluation also known as "fully lazy sharing": when the duplication of a value has to take place, it is first split into "skeleton", which is then duplicated, and "flesh" which is instead kept shared. Here, we provide two cost analyses of skeletal call-by-need. Firstly, we provide a family of terms showing that skeletal call-by-need can be asymptotically exponentially faster than call-by-need in both time and space; it is the first such evidence, to our knowledge. Secondly, we prove that skeletal call-by-need can be implemented efficiently, that is, with bi-linear overhead. This result is obtained by providing a new smooth presentation of ideas by Shivers and Wand for the reconstruction of skeletons, which is then smoothly plugged into the study of an abstract machine following the distillation technique by Accattoli et al.
@InProceedings{accattoli_et_al:LIPIcs.FSCD.2025.5,
author = {Accattoli, Beniamino and Magliocca, Francesco and Peyrot, Lo\"{i}c and Sacerdoti Coen, Claudio},
title = {{The Cost of Skeletal Call-By-Need, Smoothly}},
booktitle = {10th International Conference on Formal Structures for Computation and Deduction (FSCD 2025)},
pages = {5:1--5:22},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-374-4},
ISSN = {1868-8969},
year = {2025},
volume = {337},
editor = {Fern\'{a}ndez, Maribel},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2025.5},
URN = {urn:nbn:de:0030-drops-236206},
doi = {10.4230/LIPIcs.FSCD.2025.5},
annote = {Keywords: \lambda-calculus, abstract machines, call-by-need, cost models}
}
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