unikernel/duniverse/pgx/README.md

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+
+PGX is a pure-OCaml PostgreSQL client library, supporting Async, LWT, or
+synchronous operations.
+
+This library focuses on correctness and safety, with features like:
+
+ - It is nearly impossible to try to execute a prepared statement that hasn't
+   been prepared.
+ - Trying to run multiple queries at the same time will work properly (although
+   there's no performance benefit, since we currently don't send queries in
+   parallel).
+ - Lots of automated tests.
+ - `Pgx.Value` for parameters and returned data, encouraging people to use
+   the built-in converters instead of trying to handle everything as a string.
+ - Async and LWT support are built in, no need to write your own IO module.
+ - Mirage OS is supported via Pgx_lwt_mirage
+
+We also provide a relatively high-level interface, like `Pgx_async.execute_pipe`,
+which prepares a statement, executes it with the given parameters, returns an
+`Async.Pipe.Reader.t` (so you can stream results), and unprepares the statement
+when the query is finished.
+
+Significant portions of the code come from [PG'Ocaml](http://pgocaml.forge.ocamlcore.org/).
+
+## Setup
+
+```
+opam install pgx_async # or pgx_lwt_unix or pgx_unix or pgx_lwt_mirage
+```
+
+## Examples
+
+See [pgx_async/bin/pgx_async_example.ml](pgx_async/bin/pgx_async_example.ml) for
+a complete example of the high-level functional interface. To translate the
+example to Lwt, replace `Pgx_async` with `Pgx_lwt` and `>>|` with `>|=`. To
+translate it to synchronous IO / standard-library-only, use `Pgx_unix` and
+replace both `>>|` and `>>=` with `|>`, or just replace `>>| fun () ->` with `;`.
+
+I.e. in `Pgx_unix`, you can replace:
+
+```ocaml
+Pgx_async.execute ~params "INSERT INTO ..."
+>>| fun () ->
+```
+
+... with:
+
+```ocaml
+Pgx_unix.execute ~params "INSERT INTO ...";
+```