Dear OCaml users, 

Three months after the release of OCaml 4.12.0, the set of new features for the 
future version 4.13.0 of OCaml has been frozen. I am thus happy to announce the 
first alpha release for OCaml 4.13.0 . 

This alpha version is here to help fellow hackers join us early in our bug 
hunting and opam ecosystem fixing fun (see below for the installation instructions). 
You can see the progress on this front at https://github.com/ocaml/opam-repository/issues/18791 . 

If you find any bugs, please report them here: 

https://github.com/ocaml/ocaml/issues 

Once most major OCaml tools are supported, we will switch to beta releases. 
The full release is expected to happen in September. 

If you are interested by the ongoing list of new features and bug fixes, the 
updated change log for OCaml 4.13.0 is available at: 

https://github.com/ocaml/ocaml/blob/4.13/Changes 

Note that there is still some on-going work to support improved polling points in preparation 
for OCaml multicore. Another alpha release will be published once this work is merged. 

Happy hacking, 
Florian Angeletti for the OCaml team. 

Installation instructions 
--------------------------------- 
The base compiler can be installed as an opam switch with the following commands 

opam update 
opam switch create 4.13.0~alpha1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git 

If you want to tweak the configuration of the compiler, you can switch to the option variant with: 

opam update 
opam switch create <switch_name> --packages=ocaml-variants.4.13.0~alpha1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git 

where <option_list> is a comma separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch: 

opam switch create 4.13.0~alpha1+flambda+nffa --packages=ocaml-variants.4.13.0~alpha1+options,ocaml-option-flambda,ocaml-option-no-flat-float-array --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git 

All available options can be listed with "opam search ocaml-option". 

If you want to test this version, it is advised to install the alpha opam repository 

https://github.com/kit-ty-kate/opam-alpha-repository 

with 

opam repo add alpha git://github.com/kit-ty-kate/opam-alpha-repository.git 

This alpha repository contains various fixes in the process of being upstreamed. 

The source code for the alpha is also available at these addresses: 

https://github.com/ocaml/ocaml/archive/4.13.0-alpha1.tar.gz 
https://caml.inria.fr/pub/distrib/ocaml-4.13/ocaml-4.13.0~alpha1.tar.gz