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Here is the latest OCaml Weekly News, for the week of January 20 to 27, 2015.

  1. Detecting dead code, discovering a project's structure...
  2. new art made with ocaml
  3. Uutf 0.9.4
  4. otr 0.1.0
  5. Core Suite 112.06.02
  6. Other OCaml News

Detecting dead code, discovering a project's structure...


Continuing this old thread, Arnaud Spiwack asked and Yoann Padioleau replied:
> Could you give the relevant commands to be used in an ocaml
> project (in particular, it seems that `scheck -lang ml` fails with
> "unsuported language") ?

You first need to build the graph code database.
But for that you need to have the .cmt files generated for your
project. You can generate them just like you generate the .annot by
modifying your makefile, e.g.
by adding -bin_annot to OCAMLCFLAGS for instance.
Once the .cmt are here, do
~/pfff/codegraph -lang cmt -build /path/to/your/project

then you can use
~/pfff/scheck -lang cmt /path/to/your/project

new art made with ocaml


Tao Stein announced:
I am pleased to announce the release of my new work "A Thousand, a
Billion, a Trillion", which I believe to be the largest image ever
created (at over one terapixel). I am letting you folks know because I
coded and rendered it entirely using OCaml (well with a tiny bit of
bash script controllers thrown in).

The global work is segmented into 1,024 unique tiles, individually
watermarked, and linked to the RPC interface of my Hong Kong gallerist
for authenticity checks. If you want to own one of the works just add
"shitaoweekly" on the Chinese phone app WeChat and enter in "one
trillion" at the text interface. If you have any problems, email me. I
relish any opportunity to give back to the OCaml community, in the
ways I am most able.

This work is gaining substantial attention and interest within the
Chinese art world (in Beijing, where I work), and already some level
of international interest.

If you are interested in details, my gallerist's press release here
describes the work and also mentions the importance of the OCaml
system and community to this work:


Uutf 0.9.4


Daniel Bünzli announced:
I'd like to announce the release of Uutf 0.9.4 which should be
available shortly in opam.

You'll only be interested if you want to count bytes or if you are
using the utftrip utility distributed with the package. Details in the
release notes:

Uutf is a non-blocking streaming Unicode codec for OCaml. 


otr 0.1.0


Hannes Mehnert announced:
Off-the-record is a cryptographic protocol which is mainly used for
instant messaging. It provides encryption and authentication (plus
forward secrecy), uses AES128-CTR mode for encryption, SHA256 (and
SHA1 for MACs) and DSA for public/private keys, lots of DH computation
in oakley 5 (1536 bit).

In addition to the authenticated encrypted channel OTR features the
socialists millionaires problem (SMP) - to authenticate the other
party using a shared secret over an already established channel
(without exposing that shared secret, using some zero knowledge proofs).

I implemented this protocol, both version 2 and 3, in OCaml and am
happy to have an initial release (0.1.0, 2 clause BSD licensed),
already in the opam repository.

I'd be glad to receive feedback regarding coding style (similar to TLS
- immutable data, monadic error passing, API does not expose any
exceptions) etc.

Protocol spec:

Core Suite 112.06.02


Ben Millwood announced:
Well, this has been a long time in the pipeline. 112.06 was delayed
first by competing with other priorities, then by the winter holidays,
then by some mixups with the release process and some build issues on
OS X and 32-bit Linux. It's now finally ready for general consumption!
(shortly to be superseded by the 112.17 release anyway, oh well.)

The following packages were upgraded:

- async
- async_extended
- async_extra
- async_kernel
- async_unix
- bignum
- bin_prot
- core_bench
- core
- core_extended
- core_kernel
- custom_printf
- jenga
- ocaml_plugin
- pa_bench
- patdiff
- re2
- sexplib
- textutils
- typerep

Files for this release are available on our website and all packages
are in opam:

Unfortunately, the documentation generator has still not been fixed.
I'm hopeful it will be soon.

The full changelog:

### async_extended

- Unwound a recent change to `Mailbox` where one invocation of `receive`
  would put aside items, preventing other invocations from noticing
- Added `Delimited.Row.nth_conv_exn`, as a counterpart to
- Fixed `File_updates` handling of identical mtimes.

### async_extra

- In `Log`, exposed the raw message.
- Changed `Rpc` creators' `connection_state` to be a function that takes
  the connection and returns the state.

    This makes it possible for the connection state to actually get
    a handle on the connection itself, which simplifies a number of
    idioms for using RPC.  In particular, it makes it easier to respond
    with an RPC back to a client over client's own connection.

- Fixed some nondeterministically failing tests.
- In `Log`, made logs discard messages when their output list is empty.

    Also, removed redundant tracking of current level.

- Moved `Udp.bind_to_interface_exn` to `Unix` module in `async_unix`.
- Added `Versioned_typed_tcp.Repeater`.

    Repeater is used in the cases where we want to inspect and possibly
    alter the flow between a client and a server without having to
    change either the client or the server or the protocol between them.

### async_kernel

- Added `Deferred.Sequence` module, analogous to `Deferred.List` but for
- Modernized code style.

### async_unix

- Added `Writer.behave_nicely_in_pipeline`, which makes a program behave
  nicely when used in a shell pipeline where the consumer goes away.
- Modernized code style.
- Removed spurious overrides in `Signal`: `set` and `signal`.

    These overrides are no longer necessary because the functions moved
    from `Core.Signal` to `Core.Signal.Expert`.

- Moved `async_extra`'s `Udp.bind_to_interface_exn` to `Unix`.

### bignum

- Added functions to round from `Bignum.t` to `Bigint.t`, and to convert
  `Bigint.t` into `Bignum.t`.

### bin_prot

- Sped up `float` and `float array` operations.
- Removed a use of `Obj.magic` in code generated by `pa_bin_prot` for
  polymorphic variants that led to memory unsafety.

    Previously, `pa_bin_prot` generated this kind of code for
    polymorphic variants:

        match Obj.magic (read_int buf pos) with
        | `A as x -> x
        | `B as x -> x
        | `C -> `C (read_float buf pos)
        | _ -> fail

    and this caused the compiler to assume the result is an immediate
    value.  To fix this we removed the `as x -> x` and used the computed
    integer hash.

### core

- Renamed `Linux_ext.gettid` as `Unix.gettid`, and added OpenBSD support.

    `SYS_gettid` is not available on OpenBSD, but is used in
    `Core_extended`. See the mailing list discussion about this here:!topic/ocaml-core/51knlnuJ8MM

    Seems like the OpenBSD alternative is:

        pid_t        getthrid(void);

    although it's not defined in any header file, which is a bit unfortunate.

- Added `Piecewise_linear.precache`, which computes a lookup table that
  speeds up subsequent calls to `Piecewise_linear.get`.
- Added `Time_ns` module, representing times as 63-bit integers of
  nanoseconds since the epoch.
- Fixed build of `unix_stubs.c` on OpenBSD.
- In `Daemon`, fixed an error message regarding `WSTOPPED` (fixes #47).
- Added `Time.Span.Stable.V2`, with sexps that use new suffixes for
  microseconds (`us`) and nanoseconds (`ns`).

    `Time.Span.of_string` supports the new format, but
    `Time.Span.to_string` doesn't yet produce it -- we plan to change
    that later, after the new `of_string` has made it out more widely.

- Added `Time.Span.to_string_hum`, which gives more options for
  rendering time spans.
- Merged the `recvmmsg` stubs in `Bigstring` and `Iobuf`.

    Factored out a shared underlying `recvmmsg` call that both
    stubs use.

    Restored `-pedantic` by avoiding a C99 feature (variable-length
    stack arrays).

- Made `Date.t` abstract, and changed its representation from a 4-word
  record to an immediate int (packing year, month, day).
- In `Daemon`, changed the permissions of the `std{err,out}` files
  generated during daemonization from `0o777` to `0o644`.
- Moved `Thread_safe_queue` from `core` to `core_kernel`.

    This was done so that `Async_kernel` can use it, eliminating one of
    `Async_kernel`'s dependencies on `Core`.

    `Thread_safe_queue_unit_tests` remains `Core`, at least for now,
    because it has some dependencies on other stuff in `Core`.

### core_bench

- Solved a problem in which OCaml 4.02 was optimizing away benchmarks,
  making them meaningless.

### core_extended

- Sped up `String.is_substring` by replacing the OCaml implementation
with a call to libc `memmem`.

    `memmem` runs in 20% of the time, incurs minimal GC pressure, is
    portable among UNIXen that we target, AND it's clearer than the ML

- Made `Float_ref` support `bin_io` and `sexp`.
- Removed `gettid`, which is now available in `Core.Unix`.
- Added `Fast_int_div` module, which speeds up integer division by
  a fixed divisor.
- Moved `Sexp.of_sexp_allow_extra_fields` to core_kernel.

### core_kernel

- Made `String_id` have `Stable_containers.Comparable`.
- Changed `Gc.disable_compaction` to require an `allocation_policy`.
- Made `Option` match `Invariant.S1`.
- Added `Sequence.filter`, `compare`, and `sexp_of_t`.
- Added `With_return.with_return_option`, abstracting a common pattern
  of `with_return`.

        val with_return        : ('a return -> 'a  ) -> 'a
        val with_return_option : ('a return -> unit) -> 'a option

- Install a handler for uncaught exceptions, using
  `Printexc.set_uncaught_exception_handler`, new in OCaml 4.02.
- Changed `Day_of_week` representation to a normal variant.
- Changed `Exn.handle_uncaught` so that if it is unable to print, it
  still does `exit 1`.
- Added `Sexp.of_sexp_allow_extra_fields`, previously in
- Changed the implementation of `Exn.raise_without_backtrace` to use
  `raise_notrace`, new in OCaml 4.02.
- Added `Float` functions for converting to and from IEEE
- Added `String.Caseless` module, which compares and hashes strings
  ignoring case.
- Reimplemented `Type_equal.Id` using extensible types (new in OCaml
  4.02), removing a use of `Obj.magic`.

    Changed `Type_equal.Id.same_witness` to return `option` rather than
    `Or_error`, which allows it to be implemented without allocation.

- Removed a reference to the `Unix` module. Applications using
  `core_kernel` should be able to link without `unix.cma` again.
- Made `Char.is_whitespace` accept `\f` and `\v` as whitespace,
  matching C.

### jenga

- Support for user control of stale-artifact deletion, by allowing
  specification of an artifact-determination policy.
- Expose jenga's internal (and better - only quotes when necessary)
  definition of `Shell.escape` in `Api`
- Removed `` from the API, superseded by `Action.process`.
- Changed RPC interface as needed for build manager to switch from
  scraping error messages to RPCs.
- Fixed jenga's per-rule memo table, which mistakenly kept stale values.
- Show what target is being demanded, useful for debugging rules.
- Run user action when persistent format changes.
- When filtering buildable targets by globs, pay attention to the kinds
  allowed by the glob.

    Specifically, if the kinds don't include `` `File `` (i.e. only
    include `` `Directory ``) then we should not see any
    `buildable_targets` in the filtered list.

### ocaml_plugin

- Stopped using the `~exclusive` with `Reader`, because it doesn't work
  on read-only file systems.

    It's not even needed because these files are written atomically.

- Used a generative functor in the generated code, so the user code can
  apply generative functors at toplevel, or unpack first class modules
  that contain type components.
- Fixed bug when mli file references something defined only in
  another ml.
- Made it possible to compile a plugin in one process, and dynload the
  compiled `cmxs` file without starting async in another process.

    This was done with two new APIs in `Ocaml_dynloader.S`:

        val compile_ocaml_src_files_into_cmxs_file
          : dynloader
          -> string list
          -> output_file:string
          -> unit Deferred.Or_error.t

        val blocking_load_cmxs_file : string -> t Or_error.t

- Allowed plugins to optionally have a shebang line.
- Made `Ocaml_dynloader.find_dependencies` also support files with
  shebang lines.

### pa_bench

- Made the code generated by `pa_bench` for `BENCH` not use `ignore`,
  because OCaml 4.02 will remove dead code in some cases, meaning the
  benchmarks are no longer measuring what they should.  Instead the ignore
  is deep inside `Core_bench`, which is likely out of reach of the

    The result of the user functions given to `BENCH_FUN` and
    `BENCH_INDEXED` are changed so they don't have to return unit and
    people are encouraged not to use `ignore` when these functions don't
    return `unit` (you will get the same warning though, i.e. a warning
    if the result of your function is a function too, thus preventing
    unintended partial applications).

    For example, here are a few benchmarks and their output before the

        let x = if Random.bool () then 100 else 1001
        let r = ref 0
        BENCH "ig-1" = 10 / x
        BENCH "ig-2" = ()
        BENCH "ig-3" = phys_equal (10 / x) (Obj.magic 0)
        BENCH "ig-4" = r := (10 / x)
        BENCH "ig-5" = r := x

        | Name           | Time/Run | Percentage |
        | [] ig-1 |   3.92ns |     29.30% |
        | [] ig-2 |   3.34ns |     24.95% |
        | [] ig-3 |   3.91ns |     29.23% |
        | [] ig-4 |  13.37ns |    100.00% |
        | [] ig-5 |   3.24ns |     24.20% |

    Many of the the numbers above are much lower than they should be
    because of the implicit ignores inserted by the benchmark caused the
    division to to eliminated by the compiler. After the fix, the same
    benchmarks produced more meaningful numbers:

        | Name           | Time/Run | Percentage |
        | [] ig-1 |  12.78ns |     94.55% |
        | [] ig-2 |   3.23ns |     23.90% |
        | [] ig-3 |  13.51ns |     99.94% |
        | [] ig-4 |  13.52ns |    100.00% |
        | [] ig-5 |   3.30ns |     24.40% |

### sexplib

- Improved the implementation of `Exn.sexp_of_t`, using the unique id in
  exceptions in OCaml 4.02.

    We use the identifier to map exception constructors to converters.


We hope you find it useful!
-- Ben, on behalf of the Core team

Other OCaml News

From the ocamlcore planet blog:
Thanks to Alp Mestan, we now include in the OCaml Weekly News the links to the
recent posts from the ocamlcore planet blog at

Fast vectorizable math functions approximations:

Further OCaml GC Disharmony:

Recursive Memoize & Untying the Recursive Knot:

Securing the Unikernel:

Left-recursive versus right-recursive lists in LR parsers:


Brewing MISO to serve Nymote:

Old cwn

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Alan Schmitt