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This work makes it possible to take advantage of a compact
representation for integers in the entire system, as opposed to only
in some reduction machines. It is useful for heavily computational
applications, where even constructing terms is not possible without such
a representation.
Concretely, it replaces part of the retroknowledge machinery with
a primitive construction for integers in terms, and introduces a kind of
FFI which maps constants to operators (on integers). Properties of these
operators are expressed as explicit axioms, whereas they were hidden in
the retroknowledge-based approach.
This has been presented at the Coq workshop and some Coq Working Groups,
and has been used by various groups for STM trace checking,
computational analysis, etc.
Contributions by Guillaume Bertholon and Pierre Roux <Pierre.Roux@onera.fr>
Co-authored-by: Benjamin Grégoire <Benjamin.Gregoire@inria.fr>
Co-authored-by: Vincent Laporte <Vincent.Laporte@fondation-inria.fr>
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Users can now register string notations for custom inductives.
Much of the code and documentation was copied from numeral notations.
I chose to use a 256-constructor inductive for primitive string syntax
because (a) it is easy to convert between character codes and
constructors, and (b) it is more efficient than the existing `ascii`
type.
Some choices about proofs of the new `byte` type were made based on
efficiency. For example, https://github.com/coq/coq/issues/8517 means
that we cannot simply use `Scheme Equality` for this type, and I have
taken some care to ensure that the proofs of decidable equality and
conversion are fast. (Unfortunately, the `Init/Byte.v` file is the
slowest one in the prelude (it takes a couple of seconds to build), and
I'm not sure where the slowness is.)
In String.v, some uses of `0` as a `nat` were replaced by `O`, because
the file initially refused to check interactively otherwise (it
complained that `0` could not be interpreted in `string_scope` before
loading `Coq.Strings.String`).
There is unfortunately a decent amount of code duplication between
numeral notations and string notations.
I have not put too much thought into chosing names; most names have been
chosen to be similar to numeral notations, though I chose the name
`byte` from
https://github.com/coq/coq/issues/8483#issuecomment-421671785.
Unfortunately, this feature does not support declaring string syntax for
`list ascii`, unless that type is wrapped in a record or other inductive
type. This is not a fundamental limitation; it should be relatively
easy for someone who knows the API of the reduction machinery in Coq to
extend both this and numeral notations to support any type whose hnf
starts with an inductive type. (The reason for needing an inductive
type to bottom out at is that this is how the plugin determines what
constructors are the entry points for printing the given notation.
However, see also https://github.com/coq/coq/issues/8964 for
complications that are more likely to arise if inductive type families
are supported.)
N.B. I generated the long lists of constructors for the `byte` type with
short python scripts.
Closes #8853
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[Dune](https://github.com/ocaml/dune) is a compositional declarative
build system for OCaml. It provides automatic generation of
`version.ml`, `.merlin`, `META`, `opam`, API documentation; install
management; easy integration with external libraries, test runners,
and modular builds.
In particular, Dune uniformly handles components regardless whether
they live in, or out-of-tree. This greatly simplifies cases where a
plugin [or CoqIde] is checked out in the current working copy but then
distributed separately [and vice-versa]. Dune can thus be used as a
more flexible `coq_makefile` replacement.
For now we provide experimental support for a Dune build. In order to
build Coq + the standard library with Dune type:
```
$ make -f Makefile.dune world
```
This PR includes a preliminary, developer-only preview of Dune for
Coq. There is still ongoing work, see
https://github.com/coq/coq/issues/8052 for tracking status towards
full support.
## Technical description.
Dune works out of the box with Coq, once we have fixed some modularity
issues. The main remaining challenge was to support `.vo` files.
As Dune doesn't support custom build rules yet, to properly build
`.vo` files we provide a small helper script `tools/coq_dune.ml`. The
script will scan the Coq library directories and generate the
corresponding rules for `.v -> .vo` and `.ml4 -> .ml` builds. The
script uses `coqdep` as to correctly output the dependencies of
`.v` files. `coq_dune` is akin to `coq_makefile` and should be able to
be used to build Coq projects in the future.
Due to this pitfall, the build process has to proceed in three stages:
1) build `coqdep` and `coq_dune`; 2) generate `dune` files for
`theories` and `plugins`; 3) perform a regular build with all
targets are in scope.
## FAQ
### Why Dune?
Coq has a moderately complex build system and it is not a secret that
many developer-hours have been spent fighting with `make`.
In particular, the current `make`-based system does offer poor support
to verify that the current build rules and variables are coherent, and
requires significant manual, error-prone. Many variables must be
passed by hand, duplicated, etc... Additionally, our make system
offers poor integration with now standard OCaml ecosystem tools such
as `opam`, `ocamlfind` or `odoc`. Another critical point is build
compositionality. Coq is rich in 3rd party contributions, and a big
shortcoming of the current make system is that it cannot be used to
build these projects; requiring us to maintain a custom tool,
`coq_makefile`, with the corresponding cost.
In the past, there has been some efforts to migrate Coq to more
specialized build systems, however these stalled due to a variety of
reasons. Dune, is a declarative, OCaml-specific build tool that is on
the path to become the standard build system for the OCaml ecosystem.
Dune seems to be a good fit for Coq well: it is well-supported, fast,
compositional, and designed for large projects.
### Does Dune replace the make-based build system?
The current, make-based build system is unmodified by this PR and kept
as the default option. However, Dune has the potential
### Is this PR complete? What does it provide?
This PR is ready for developer preview and feedback. The build system
is functional, however, more work is necessary in order to make Dune
the default for Coq.
The main TODOs are tracked at https://github.com/coq/coq/issues/8052
This PR allows developers to use most of the features of Dune today:
- Modular organization of the codebase; each component is built only
against declared dependencies so components are checked for
containment more strictly.
- Hygienic builds; Dune places all artifacts under `_build`.
- Automatic generation of `.install` files, simplified OPAM workflow.
- `utop` support, `-opaque` in developer mode, etc...
- `ml4` files are handled using `coqp5`, a native-code customized
camlp5 executable which brings much faster `ml4 -> ml` processing.
### What dependencies does Dune require?
Dune doesn't depend on any 3rd party package other than the OCaml compiler.
### Some Benchs:
```
$ /usr/bin/time make DUNEOPT="-j 1000" -f Makefile.dune states
59.50user 18.81system 0:29.83elapsed 262%CPU (0avgtext+0avgdata 302996maxresident)k
0inputs+646632outputs (0major+4893811minor)pagefaults 0swaps
$ /usr/bin/time sh -c "./configure -local -native-compiler no && make -j states"
88.21user 23.65system 0:32.96elapsed 339%CPU (0avgtext+0avgdata 304992maxresident)k
0inputs+1051680outputs (0major+5300680minor)pagefaults 0swaps
```
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