Quickcheck_Types defines a number of artificial types that quickcheck can use to instantiate type variables that occur in a theorem. Normally, quickcheck instantiates them with int provided that the sort constraints do not prevent this. In Enum.thy, there are already the types finite_X that quickcheck uses for enumerable types (type class enum) such that quantifiers can be unfolded into conjunctions or disjunctions.

The types in Quickcheck_Types now do the same for the lattices type class hierarchy, because int and the finite_X types cannot be used for type variables with sort lattice (or top/bot/...).

I believe that it should be fairly simple to adjust Quickcheck_Types to Isabelle2014. However, this only makes sense if it becomes part of Main. Otherwise, it will remain just a library theory that hardly anyone knows about and no one uses.

Moreover, we should make sure that Quickcheck_Types fits to the current code generator setup for lattices. IIRC, Florian has reworked a lot there over the past years. At the very least, we should have some test cases (e.g. in HOL/ex) to check that Quickcheck_Types works as expected.

If there's consensus on reviving this theory, I can do the changes to Quickcheck_Types such that Isabelle2014 digests it. This is probably all that can be done before the release as most of us will be busy in Vienna next week. A move to Main is something for the next release.

Andreas


On 11/07/14 13:22, Lawrence Paulson wrote:
I’m afraid that I don’t even know what it is.
Larry


On 11 Jul 2014, at 12:21, Florian Haftmann 
<florian.haftm...@informatik.tu-muenchen.de> wrote:

The issue that src/HOL/Library/Quickcheck_Types.thy is dead and broken
has not been addressed since before the last release.

So, which path to follow?  Is there any interested in a serious repair
effort?  Otherwise, we should honestly drop it.

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