Hi Jan,

Here is a quick 'n' dirty restinio package:

--8<---------------cut here---------------start------------->8---
(define-public restinio
  (package
    (name "restinio")
    (version "0.6.0.1")
    (source (origin
              (method git-fetch)
              (uri (git-reference
                    (url "https://github.com/Stiffstream/restinio.git")
                    (commit (string-append "v." version))))
              (file-name (git-file-name name version))
              (sha256
               (base32
                "1c25kpx652nng8m1sqf5an2c3c4g3k6zj85mkkaxzk88iwfzq1s8"))))
    (build-system cmake-build-system)
    (inputs                             ; TODO: Need to force-keep references on some inputs, e.g. boost.
     `(("zlib" ,zlib)
       ("catch2" ,catch-framework2)
       ("openssl" ,openssl)
       ("fmt" ,fmt)
       ("boost" ,boost)
       ;;("asio", asio) ; TODO: Use external asio?  Need -DRESTINIO_USE_BOOST_ASIO_VALUES=shared.
       ("pcre" ,pcre)
       ("pcre2" ,pcre2)
       ("sobjectizer" ,sobjectizer)))
    (arguments
     `(#:configure-flags '("-DRESTINIO_INSTALL=on")
       #:tests? #f ; TODO: The tests are called from the root CMakelist, need RESTINIO_TEST=on.
       #:phases
       (modify-phases %standard-phases
         (add-after 'unpack 'change-directory
           (lambda _
             (chdir "dev/restinio")
             #t)))))
    (home-page "https://stiffstream.com/en/products/restinio.html")
    (synopsis "C++14 library that gives you an embedded HTTP/Websocket server")
    (description "RESTinio is a header-only C++14 library that gives you an embedded
HTTP/Websocket server.  It is based on standalone version of ASIO
and targeted primarily for asynchronous processing of HTTP-requests.")
    (license license:bsd-3)))
--8<---------------cut here---------------end--------------->8---

The CMakeLists are a bit convoluted, so I simply skipped the root one
and when straight into the restinio subfolder.

I'm too lazy to figure out how to run the tests at the moment.

Note: the comma "," in Scheme means it "unquotes" the following
expression, and thus the space must be put before it, not after.

Wrong:

  ("boost", boost)

Correct:

  ("boost" ,boost)


Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/