*Disclaimer*: This is intended for discussion
My impression is that the with-exceptions backend is to be superseded by the
without-exception backend, which is more general and more efficient. Therefore,
seeing the added complexity of maintaining the two in parallel, I see no good
reason to keep the with-exceptions version now that the equivalence of their
semantics have been proved.
It will also be nice to reduce divergences between the different backends ; and
this should make further simplifications possible (e.g. some thunkings may no
longer be needed)
Of course I am ready to hear arguments in favor of keeping it, be it in the mid-
or long-term.
This patch removes the `--avoid-exceptions` flag, making it the only option, and
the corresponding `with_exceptions` variant of the dcalc->lcalc translation. It
doesn't do further simplifications.
NOTE: This is a temporary solution
A future approach could be to have Catala generate a module loader (with the
proper hash), relieving the user implementation from having to do the
registration.
This includes a few separate changes:
- pass visibility information of declarations (depending on wether the
declaration was in a ```catala-metadata block or not)
- add reasonable hash computation functions to discriminate the interfaces. In
particular:
* Uids have a `hash` function that depends on their string, but not on their
actual uid (which is not stable between runs of the compiler) ; the existing
`hash` function and its uses have been renamed to `id`.
* The `Hash` module provides the tools to properly combine hashes, etc. While
we rely on `Hashtbl.hash` for the atoms, we take care not to use it on any
recursive structure (it relies on a bounded traversal).
- insert the hashes in the artefacts, and properly check and report those (for
OCaml)
**Remains to do**:
- Record and check the hashes in the other backends
- Provide a way to get stable inline-test outputs in the presence of module
hashes
- Provide a way to write external modules that don't break at every Catala
update.
