This library aims to collect reusable, general effects-based components we have seen when constructing our proof assistants using OCaml 5. All components here have appeared in various tutorials on algebraic effects; algaeff wraps these well-known components into an OPAM package.

We use semantic versioning. Breaking changes will bump the major version number.

• Algaeff.State: mutable states
• Algaeff.Reader: read-only environments
• Algaeff.Sequencer: making a Seq.t
• Algaeff.Mutex: simple locking to prevent re-entrance
• Algaeff.UniqueID: generating unique IDs

Effects-based concurrency (cooperative lightweight threading) was already tackled by other libraries such as Eio and Affect. This library focuses on the rest.

There are a few other useful functions:

• Algaeff.Fun.Deep.finally: call continue or discontinue accordingly.
• Algaeff.Fun.Shallow.finally_with: same as above, but for shallow effect handlers.

You need OCaml 5.

module S = Algaeff.State.Make (Int)

let forty_two = S.run ~init:100 @@ fun () ->
  print_int (S.get ()); (* this will print out 100 *)
  S.set 42;
  S.get ()

Here is the API documentation.