[cwn] Attn: Development Editor, Latest OCaml Weekly News

[Alan Schmitt]

Hello

Here is the latest OCaml Weekly News, for the week of December 21 to 28,
2021.

Happy Winter Solstice!

Table of Contents
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New release of Feat
Debugger support for OCaml
Old CWN


New release of Feat
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  Archive:
  <https://sympa.inria.fr/sympa/arc/caml-list/2021-12/msg00010.html>


François Pottier announced
──────────────────────────

  I am happy to announce a new release of Feat, a library that offers
  support for counting, enumerating, and sampling objects of a certain
  kind, such as (say) the inhabitants of an algebraic data type.

  This new release integrates a contribution by Jonah Beckford. The
  library is now split in three packages: `feat-core' is parameterized
  over an implementation of big integers; `feat' instantiates
  `feat-core' with big integers provided by `zarith'; `feat-num'
  instantiates it with big integers provided by `num'.

  ┌────
  │ opam update
  │ opam install feat
  │ # or: opam install feat-num
  └────

  More details can be found here:

  <https://gitlab.inria.fr/fpottier/feat/>


Debugger support for OCaml
══════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/debugger-support-for-ocaml/9057/1>


Christian Lindig asked
──────────────────────

  What is the current state of debugger support for OCaml? I am aware of
  ocamldebug but every time I'm trying to use it I feel thrown back to
  2000 where it essentially existed in the same form (and still has no
  command line editing built in). Despite the powerful concept of time
  traveling, it does not seem very useful today. For example, it can't
  be attached to a running program and it does not work with native
  code. What is the state of GDB support? What debugger would one use on
  macOS?


linoscope replied
─────────────────

  Have you taken a look at ocamlearlybird ([github], [announcement])? I
  have never used it myself, but based on [the demo] it seems pretty
  nice.


[github] <https://github.com/hackwaly/ocamlearlybird>

[announcement]
<https://discuss.ocaml.org/t/ann-ocamlearlybird-1-0-0-beta1/7180>

[the demo] <https://imgur.com/U3GDHXM>


Sid Kshatriya also replied
──────────────────────────

  I agree that debugging in OCaml seems to be stuck in time.

  This is extremely unfortunate because it is able to do time traveling
  (as you mention) which is something that many other languages still
  cannot boast.

  • `ocamldebug' does not work properly when there is more than 1 OS
    thread
  • As types are erased during compile time in OCaml, it can be
    difficult to debug polymorphic functions. Rust and C/C++
    monomorphise all code so there is never any confusion about the type
    of anything in the debugger. Golang and Java have type information
    available during runtime so again, debugging is easy. In this
    respect OCaml is similar to Haskell while using the byte-code
    debugger.
  • The future of ocamldebug is unknown on multicore

  As far as GDB support is concerned, there was a project to improve GDB
  support (so you could print out variables like in ocamldebug IIUC) but
  it never got merged into trunk.

  However, if you are interested in low level debugging in gdb, here is
  a [recent] answer related to this.

  My guess is that `ocamldebug' will continue to work for the single
  domain, single thread case in OCaml 5.00 but ocamldebug is currently
  broken in multicore there (AFAIK).


[recent]
<https://discuss.ocaml.org/t/multicore-ocaml-september-2021-effect-handlers-will-be-in-ocaml-5-0/8554/9>


Old CWN
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  [Alan Schmitt]


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