Compiling Erssical requires the following software to be installed:

• OCaml >= 4.12.0,
• Dune >= 2.5,
• Cohttp >= 4.0.0,
• Lwt >= 5.4.0 with lwt_ppx,
• Icalendar >= 0.1.5,
• OCaml-RSS >= 3.0,
• Xtmpl >= 0.19.0,
• Lru-cache >= 0.3.

Erssical is also available in OPAM:

opam install erssical

After extracting the source tree, go to the extracted directory and type:

make install

This will install the erssical library, erssical[.byte] and erssical-server[.byte] using Dune.