[ANN] opam 2.6.0~alpha1

Hi everyone, We are happy to announce the first alpha release of opam 2.6.0. This is the culmination of 2 years of team work requiring large internal changes, we hope you’ll enjoy it. This version i...

discuss.ocaml.org

Release of OCaml 5.5.0

We have the pleasure of celebrating the birthday of Blaise Pascal by announcing the release of OCaml version 5.5.0. Release Highlights Some of the highlights of OCaml 5.5.0 are: Module-dependent Functions Modules can now be used as function arguments in a form of lightweight functors. For instance, we can define a function for printing a map generated by the Map.Make functor: let pp_map (module M: Map.S) pp_key pp_v ppf set = if M.is_empty set then Format.fprintf ppf "ø" else let pp_sep ppf () = Format.fprintf ppf ",@ " in let pp_binding ppf (k,v) = Format.fprintf ppf "@[%a@ =@ %a@]" pp_key k pp_v v in Format.fprintf ppf "@[{@ %a@ }@]" (Format.pp_print_seq ~pp_sep pp_binding) (M.to_seq set) We can then apply this function on a string map module String_map = Map.Make(String) with let () = let m = String_map.of_list ["Zero", "Zero"; "One", "Un"] in let pp_str = Format.pp_print_string in Format.printf "%a@." (pp_map (module String_map) pp_str pp_str) m Compared to first-class modules, the type of the function pp_map type 'a printer = Format.formatter -> 'a -> unit val pp_map: (module M: Map.S) -> M.key printer -> 'a printer -> 'a M.t printer is dependent over the value of the module S, and thus the function can only applied over a statically known module: let f (): (module Map.S) = if Random.bool () then (module Map.Make(Int)) else (module Map.Make(Float)) let fail = pp_map (f ()) Error: This expression has type (module M : Map.S) -> (Format.formatter -> M.key -> unit) -> (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a M.t -> unit but an expression was expected of type (module Map.S) -> 'b The module M would escape its scope This function is module-dependent. The dependency is preserved when the function is passed a static module argument (module M : S) or (module M). Its argument here is not static, so the type-checker tried instead to change the function type to be non-dependent. Relocatable Compiler A compiler installation can now be moved or copied with no risk of hard-to-debug errors due to mixing incompatible bytecode runtime interpreters. In practice, this means that creating a local switch when there is a global switch with the same compiler version and configuration available can be done by cloning the global switch rather than recompiling the whole compiler. This should considerably reduce the time required to create new local opam switches out-of-the-box. Polymorphic Functions as Function Arguments Higher-rank polymorphic functions can now be defined directly by using an explicit type annotation in a function argument let apply_map (map: 'a 'b. ('a -> 'b) -> 'a list -> 'b list) = map string_of_int [1;2;3], map List.singleton ["x"; "y"] let _ = apply_map List.map Previously defining such a function required going through either a record or an object with a polymorphic field or methods type map = { map: 'a 'b. ('a -> 'b) -> 'a list -> 'b list } let apply_map {map} = map string_of_int [1;2;3], map List.singleton ["x"; "y"] Search and Replace Substring Functions The String module has been extended with many functions for searching and replacing substrings inside a string. let _true = String.includes ~affix:"aba" "abbaba" let sentence = String.replace_all ~sub:"𝄽" ~by:"word" "A 𝄽 is re𝄽ed" The substring search is using the 2-way string matching algorithm which has the advantage of requiring constant space memory overhead independently of the needle size. Generalised Local Definitions It is now always possible to define locally a type, a class, a module type or any kind of item that can be defined globally: let mandelbrot n x = let type t = Converge | Escape of int in ... match orbit n x with | Converge -> 0 | Exit_at n -> colorize n External Types When interfacing with foreign function libraries, it is now possible to define external type type int_gmp = external "mpz_t" type float_gmp = external "mpf_t" Compared to an abstract type definition, the external type name "mpz_t" (resp. mpf_t) makes the type distinguishable from any non-abstract types or external types with a different name. In particular, this makes FFI types better behaved when combined with Generalised Abstract Data Types (GADTs). For instance, The typechecker is able to prove that let ok: (int_gmp,[` A] ) Type.eq -> _ = function _ -> . is a total function because the external type int_gmp is not compatible with a polymorphic variant type. Warning: Abstract types in the current module The astute reader has probably noticed in the definition above that, in OCaml 5.4.0, the typechecker does accept type int_gmp let ok: (int_gmp, [` A] ) Type.eq -> _ = function _ -> . as total. Indeed until OCaml 5.5.0, abstract types defined in the current module type a type b were considered as unique and provably different let f: 'x. (a,b) Type.eq -> 'x = function _ -> . However, this special rule for local definition of abstract types was very brittle. As soon as one moved outside of the current module, it was no longer possible to prove that the types were different. module M = struct type a type b end let fail: 'x. (M.a,M.b) Type.eq -> 'x = function _ -> . Error: This match case could not be refuted. Here is an example of a value that would reach it: Equal This special typechecking rule has been removed in OCaml 5.5.0. If you were relying on it, for instance, because you used an abstract type as type-level label in a GADTs, you can change your abstract type definition to a possibly private abbreviation of a polymorphic variant type a = private [`A] type b = [`B] or a (possibly private) sum type type a = A type b = private B If you were using an abstract type as both a type-level label and a FFI type, you can now use an external type definition which will give you a provably distinct type even outside of the current module. GC improvements Some of the ongoing work to improve the pacing of the garbage collector has been integrated in OCaml 5.5.0, two of the important changes in OCaml 5.5 GC are * the addition of a sweep-only phase at the start of major GC * the addition of an idle phase to smooth the behaviour of the GC at the start. Many incremental changes * The Windows implementation is no more reliant on Winpthreads * Around 60 new standard library functions * Around 90 various improvements * A dozen of documentation updates * Around 40 bug fixes Please report any unexpected behaviours on the OCaml issue tracker and post any questions or comments you might have on our discussion forums. The full list of changes can be found in the full changelog. --- Installation Instructions The base compiler can be installed as an opam switch with the following commands: opam update opam switch create 5.5.0 The source code for the release is also directly available on: * GitHub * OCaml archives at Inria Fine-Tuned Compiler Configuration If you want to tweak the configuration of the compiler, you can switch to the option variant with: opam update opam switch create ocaml-variants.5.5.0+options where is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch: opam switch create 5.5.0+flambda+nffa ocaml-variants.5.5.0+options ocaml-option-flambda ocaml-option-no-flat-float-array

dlvr.it

Self-hosting email the hard way from your own routable IPv4 block up

How we refreshed self-hosted Recoil email with our own RIPE-allocated IPv4 block, and deployed Postfix/rspamd/Dovecot to get full SPF/DKIM/DMARC deliverability.

anil.recoil.org

Caml In The Capital - June

Caml in the Capital is London's OCaml meetup group. We bring together developers, researchers, and enthusiasts to discuss OCaml.

eventbrite.com

Integrating Standard Site Into Bluesky · bluesky-social atproto · Discussion #4978

The Bluesky team is working on integrating site.standard.* lexicons. For people using the Bluesky app, this means that when they come across a link published with a Standard.site record, they’ll ge...

github.com

OCaml-LSP 1.26.0

This new release of OCaml-LSP brings several new features and improvements, including new custom requests, support for range formatting, and enhanced hover capabilities. See the related announcement on the Discuss forums.

dlvr.it

AI, open code and vulnerability risk in the public sector

Guidance for safely publishing source code in the open, and reducing the risk of AI-accelerated vulnerability discovery.

gov.uk

Reliable AI-free Support Bots | You don't need an LLM for that | Computational Conversations

This post introduces a new approach to creating LLM-free support bots. In addition to providing a great user experience, these bots are reliable, speedy, hallucination free, and overall cheaper, simpl...

computational.chat

OxCaml Labs

OxCaml Labs

anil.recoil.org

Adoption of the Neovim plugin for OCaml

We recently released a new NeoVim plugin for OCaml. It has been live for a few months now (you can find the announcement here if you are curious), and we would like to know what you think of it. The next step is to improve the plugin in order to better meet the expectations of the users. To do that, it would be very helpful for us if you could reply to the following poll. Do not hesitate to share your thoughts about the plugin, both positive and negative, and any ideas are also welcome. We are ...

discuss.ocaml.org

Grammarly Is Facing a Class Action Lawsuit Over Its AI ‘Expert Review’ Feature

The feature, which Grammarly shut down Wednesday, presented editing suggestions as if they came from established authors and academics—without their consent.

wired.com

Control structures in programming languages

Xavier Leroy

xavierleroy.org

The Infrastructure Stack Is Getting Faster. Terraform Is Not.

Every part of the stack is accelerating except infrastructure. Terraform has the ecosystem but not the speed. That's fixable.

stategraph.dev

Gavin Gray, Anil Madhavapeddy, KC Sivaramkrishnan, Richard Eisenberg, Chris Casinghino, Will Crichton, Shriram Krishnamurthi, Patrick Ferris, Max Slater, Megan Del Vecchio, Diana Kalinichenko, Nadia Razek

gavinleroy.com

FUN OCaml 2025 - Live from Warsaw! Part 2

YouTube video by FUN OCaml

youtube.com