Thanks. Does it make sense that changing a function definition from point-free to an explicit definition should eliminate this exception? Because that seems to have been the problem.

On Wed, Sep 10, 2014 at 6:20 PM, Jeremy Yallop <yallop@gmail.com> wrote:
On 10 September 2014 21:32, Yotam Barnoy <yotambarnoy@gmail.com> wrote:
> I just encountered this nasty RUNTIME error in my code. What does it mean?
> How does it happen?

The behaviour is documented in the manual:

   http://caml.inria.fr/pub/docs/manual-ocaml-400/manual021.html#toc75

See the paragraph beginning "Currently, the compiler requires [...]".