Currently generators and shrinkers (and observers, which generate functions
-- the analog to CoArbitrary in Haskell) are all written manually.  I do
intend to add syntax for them, but that's been pending on a few other
updates, especially our switch from camlp4 to ppx syntax extensions.  We do
print counterexamples using s-expressions, as you say.

Our shrinkers use the type ('a -> 'a Sequence.t), where Sequence.t is a
lazy, unmemoized sequence type in Core.

On Tue, Sep 15, 2015 at 10:30 AM, Simon Cruanes <simon.cruanes.2007@m4x.org>
wrote:

> I am working on adding shrinking into qtest
> (https://github.com/vincent-hugot/iTeML/), and I'm curious about what
> design choices you did. Haskell literate mentions
>
> shrink: 'a -> 'a list
>
> to shrink values, but on large counter-examples like large lists, it
> might be very slow. I'm trying to use iterators to generate shrunk(?)
> values lazily.
>
> Also, do Core users write random generators or shrinking functions
> themselves, or do you have a deriver for them? I assume you use "with sexp"
> to display counter-examples.
>
> Cheers,
>
> Le Tue, 15 Sep 2015, Carl Eastlund a écrit :
> > Glad you like it.  Our Quickcheck implementation is new and its design is
> > still somewhat of an experiment, so I can't claim it's a mature library
> as
> > originally asked for in this thread, but of course we appreciate feedback
> > from early adopters.  As Yaron said, I'm writing up a blog post that will
> > go into more detail about it.
> >
> > We just had an intern, Daniel Spencer, implement shrinking.  That will
> make
> > its way to the public release shortly.
> >
> > On Tue, Sep 15, 2015 at 10:06 AM, Gabriel Scherer <
> gabriel.scherer@gmail.com
> > > wrote:
> >
> > >
> > >>
> https://github.com/janestreet/core_kernel/blob/master/src/quickcheck_generator.mli
> > >>
> > >>
> https://github.com/janestreet/core_kernel/blob/master/src/quickcheck_observer.mli
> > >>
> > >
> > > This is very nice.
> > > I hope the library will also get shrinking support, because it not so
> easy
> > > to do, and important in practice.
> > >
> > > On Tue, Sep 15, 2015 at 3:09 PM, Yaron Minsky <yminsky@janestreet.com>
> > > wrote:
> > >
> > >> Core_kernel has a recently added quickcheck library.  Carl Eastlund,
> who
> > >> is the main author, is finishing up a blog post describing it, but
> you can
> > >> start with the documentation in this file:
> > >>
> > >>
> > >>
> https://github.com/janestreet/core_kernel/blob/master/src/quickcheck_generator.mli
> > >>
> > >> On Sun, Sep 13, 2015 at 11:52 AM, Simon Cruanes <
> > >> simon.cruanes.2007@m4x.org> wrote:
> > >>
> > >>> There is also qtest (also called iTeML on github) which is a bit
> > >>> special: it's a testing framework providing unit testing through
> OUnit,
> > >>> and simple random testing; its specificy is that tests can be
> written in
> > >>> comments within the module to test, so that the code itself has no
> > >>> additional
> > >>> dependencies or code bloat due to tests. It is very easy to write new
> > >>> tests, since you don't have to add specific test modules.
> > >>> It is used, afaik, at least in Batteries and in containers.
> > >>>
> > >>> I am probably going to work on making qtest and qcheck a bit closer,
> if
> > >>> qtest's developper(s) agree.
> > >>>
> > >>> Cheers,
> > >>>
> > >>> Le Sun, 13 Sep 2015, Török Edwin a écrit :
> > >>> > On 09/13/2015 11:09 AM, Keiko Nakata wrote:
> > >>> > > Hi,
> > >>> > >
> > >>> > > I am looking for (reasonably matured and hopefully easy to
> install)
> > >>> QuickCheck-like property based testing software for OCaml code.
> > >>> > >
> > >>> > > Any information is appreciated!
> > >>> >
> > >>> > There is qcheck.0.4, quickcheck.1.0.2 and kaputt.1.2 on opam.
> > >>> > qcheck has documentation in the mli, integration with OUnit and
> quite
> > >>> easy to get started with.
> > >>> > Kaputt also has reducers (to produce smaller counterexamples), and
> > >>> SmallCheck-like enumeration tests.
> > >>> >
> > >>> > I haven't tried quickcheck, and haven't found an equivalent to
> > >>> SmartCheck's counterexample generalization [1]
> > >>> >
> > >>> > [1] https://www.cs.indiana.edu/~lepike/pubs/smartcheck.pdf
> > >>> >
>
>
> --
> Simon Cruanes
>
> http://weusepgp.info/
> key 49AA62B6, fingerprint 949F EB87 8F06 59C6 D7D3  7D8D 4AC0 1D08 49AA
> 62B6
>



-- 
Carl Eastlund