capnproto ocapn flailing in ocaml (WIP)

packages/ocproto/CONTRIBUTING.md

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+# Contributing - Design Notes
+
+## see playgroud PR
+
+notes are moving to https://github.com/endojs/playground/pull/9
+
+## ocaml.org curl bash
+
+```
+bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh)"
+opam init
+```
+
+hm... `Do you want opam to modify ~/.profile?`
+I'd rather use direnv. Yay! it's a supported option: [Using direnv](https://ocaml.org/docs/opam-path#using-direnv).
+
+... ocaml-base-compiler.5.1.1 ...
+
+```
+eval $(opam env --switch=default)
+```
+
+devtools:
+
+```
+opam install ocaml-lsp-server odoc ocamlformat utop
+```
+
+195 dependencies... pretty quick, though...
+
+```
+opam exec -- dune init proj ocproto
+```
+
+... [OCaml Platform \- Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=ocamllabs.ocaml-platform)
+
+```
+dune build --watch --terminal-persistence=clear-on-rebuild
+```
+
+crikey! that was fast.
+
+## Road not taken: opam-nix
+
+Following a [Feb 2023 item on opam-nix](https://www.tweag.io/blog/2023-02-16-opam-nix/), we begin with:
+
+```console
+$ nix flake init -t github:tweag/opam-nix
+$ git add flake.nix
+```
+
+But then `nix develop` failed with `error: attribute 'ocproto' missing`.

packages/ocproto/bin/dune

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+(executable
+ (public_name ocproto)
+ (name main)
+ (libraries ocproto))

packages/ocproto/bin/main.ml

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+let () = print_endline "Hello, World!"
+
+open Ocproto
+
+let () = print_endline (Ocapnimpl.show Ocapnimpl.val1)

packages/ocproto/dune-project

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+(lang dune 3.14)
+
+(name ocproto)
+
+(generate_opam_files true)
+
+(source
+ (github username/reponame))
+
+(authors "Author Name")
+
+(maintainers "Maintainer Name")
+
+(license LICENSE)
+
+(documentation https://url/to/documentation)
+
+(package
+ (name ocproto)
+ (synopsis "A short synopsis")
+ (description "A longer description")
+ (depends ocaml dune)
+ (tags
+  (topics "to describe" your project)))
+
+; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project

packages/ocproto/lib/dune

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+(library
+ (name ocproto)
+ (libraries capnp))

packages/ocproto/lib/ocapn.capnp

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+# ocapn.capnp
+@0xcd301da1d95b8242;
+
+struct Value {
+  union {
+    ## Atoms ##
+
+    undefined @0 :Void;
+    null @1 :Void;
+    bool @2 :Bool;
+    float64 @3 :Float64;
+
+    unsignedInt @4 :Data;
+    # Non-negative integer, in big-endian format
+    negativeInt @5 :Data;
+    # Negative integer. value is `-1 - n`, where `n`
+    # is the data interpreted as an unsigned big-endian integer.
+
+    string @6 :Text;
+    byteString @7 :Data;
+    symbol @8 :Text; # Might be removed, pending #46.
+
+    ## Containers ##
+
+    list @9 :List(Value);
+
+    struct @10 :List(StructField);
+    # Duplicate keys are not allowed; will need to enforce this at a higher level
+    # of abstraction.
+
+    tagged :group {
+      label @11 :Text;
+      value @12 :Value;
+    }
+
+    capability @13 :Cap;
+
+    error @14 :Error;
+  }
+}
+
+struct StructField {
+  key @0 :Text;
+  value @1 :Value;
+}
+
+interface Cap {
+  # TODO
+}
+
+struct Error {
+  # TODO, pending #10.
+}