Trustworthy Systems

PureCake: A verified compiler for a lazy functional language

Authors

Hrutvik Kanabar, Samuel Vivien, Oskar Abrahamsson, Magnus O. Myreen, Michael Norrish, Johannes \AAman Pohjola and Riccardo Zanetti

University of Kent
United Kingdom\ \'Ecole Normale Sup\'erioeure PSL
France\ Chalmers University
Sweden\ Australian National University
Australia\ UNSW Sydney
Australia

Abstract

We present PureCake, a mechanically-verified compiler for PureLang, a lazy, purely functional programming language with monadic effects. PureLang syntax is Haskell-like and indentation-sensitive, and its constraint-based Hindley-Milner type system guarantees safe execution. We derive sound equational reasoning principles over its operational semantics, dramatically simplifying some proofs. We prove end-to-end correctness for the compilation of PureLang down to machine code—the first such result for any lazy language—by targeting CakeML and composing with its verified compiler. Multiple optimisation passes are necessary to handle realistic lazy idioms effectively. We develop PureCake entirely within the HOL4 interactive theorem prover.

BibTeX Entry

  @article{Kanabar_VAMNP_23,
    author           = {Hrutvik Kanabar and Samuel Vivien and Oskar Abrahamsson and Magnus O. Myreen and Michael Norrish and
                        Johannes {\AA}man Pohjola and Riccardo Zanetti},
    doi              = {10.1145/3591259},
    journal          = {Proceedings of the ACM on Programming Languages},
    number           = {PLDI},
    pages            = {952--976},
    paperurl         = {https://trustworthy.systems/publications/papers/Kanabar_VAMNP_23.pdf},
    publisher        = {ACM},
    title            = {{PureCake}: {A} Verified Compiler for a Lazy Functional Language},
    volume           = {7},
    year             = {2023}
  }

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