Abstract

We implemented a command that can be used to easily generate elements of a restricted type {x :: ‘a. P x}, provided the definition is of the form f ys = (if check ys then Some(generate ys :: ‘a) else None) where ys is a list of variables y1 ... yn and check ys ==> P(generate ys) can be proved.

In principle, such a definition is also directly possible using the lift_definition command. However, then this definition will not be suitable for code-generation. To this end, we automated a more complex construction of Joachim Breitner which is amenable for code-generation, and where the test check ys will only be performed once. In the automation, one auxiliary type is created, and Isabelle’s lifting- and transfer-package is invoked several times.

BibTeX

@article{RT-AFP14c, 
  author  = {René Thiemann},
  title   = {Lifting Definition Option},
  journal = "Archive of Formal Proofs",
  month   = oct,
  year    = 2014,
  note    = {\url{https://www.isa-afp.org/entries/Lifting_Definition_Option.html},
            Formal proof development},
  ISSN    = {2150-914x},
}