2026-08-06T20:38:55Z https://drops.dagstuhl.de/oai

oai:drops-oai.dagstuhl.de:20352 2024-07-05T06:20:34Z ddc:004 open_access

Mirroring Call-By-Need, or Values Acting Silly Accattoli, Beniamino Lancelot, Adrienne Lambda calculus intersection types call-by-value call-by-need Call-by-need evaluation for the λ-calculus can be seen as merging the best of call-by-name and call-by-value, namely the wise erasing behaviour of the former and the wise duplicating behaviour of the latter. To better understand how duplication and erasure can be combined, we design a degenerated calculus, dubbed call-by-silly, that is symmetric to call-by-need in that it merges the worst of call-by-name and call-by-value, namely silly duplications by-name and silly erasures by-value. We validate the design of the call-by-silly calculus via rewriting properties and multi types. In particular, we mirror the main theorem about call-by-need - that is, its operational equivalence with call-by-name - showing that call-by-silly and call-by-value induce the same contextual equivalence. This fact shows the blindness with respect to efficiency of call-by-value contextual equivalence. We also define a call-by-silly strategy and measure its length via tight multi types. Lastly, we prove that the call-by-silly strategy computes evaluation sequences of maximal length in the calculus. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Beniamino Accattoli and Adrienne Lancelot 2024 Is Part Of LIPIcs, Volume 299, 9th International Conference on Formal Structures for Computation and Deduction (FSCD 2024) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.FSCD.2024.23 urn:nbn:de:0030-drops-203527 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2024.23 eng https://creativecommons.org/licenses/by/4.0/legalcode