initial setup

Author: smolkaj

.gitignore

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+_build
+*.install
+*.merlin

Makefile

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+INSTALL_ARGS := $(if $(PREFIX),--prefix $(PREFIX),)
+
+build:
+	time -p jbuilder build @install
+
+install:
+	jbuilder install $(INSTALL_ARGS)
+
+uninstall:
+	jbuilder uninstall $(INSTALL_ARGS)
+
+reinstall: uninstall reinstall
+
+clean:
+	jbuilder clean
+
+doc:
+	jbuilder build @doc
+
+test: build install
+	ocaml-python
+
+all: build test doc
+
+.PHONY: build install uninstall reinstall clean doc test all

ocaml-python.opam

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+opam-version: "1.2"
+available: [ ocaml-version >= "4.05.0" ]
+version: "0.1"
+maintainer: "Steffen Smolka <[email protected]>"
+homepage: "http://www.cs.cornell.edu/~smolka"
+dev-repo: "https://github.com/smolkaj/ocaml-python.git"
+
+build: ["jbuilder" "build" "-p" name "-j" jobs]
+build-doc: ["jbuilder" "build" "@doc" "-p" name "-j" jobs]
+build-test: ["jbuilder" "runtest" "-p" name "-j" jobs]
+install: ["jbuilder" "install" "-p" name "-j" jobs]
+
+depends: [
+  "jbuilder" {>="1.0+beta13"}
+  "core"   {>= "0.9.0"}
+  "findlib"
+]

python/jbuild

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+(jbuild_version 1)
+
+(rule
+ ((targets  (my-script.pyc))
+  (deps     (my-script.py))
+  (action   (run python3 -m compileall -b ${^}))
+ )
+)
+
+(install
+  ((section lib)
+   (files   (my-script.pyc))
+   (package ocaml-python)
+  ))

python/my-script.py

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+from __future__ import print_function
+import sys
+import fileinput
+
+# just like print, but use stderr instead of stdout
+def eprint(*args, **kwargs):
+    print(*args, file=sys.stderr, **kwargs)
+
+def main():
+    eprint("[python] waiting for input...")
+    for line in sys.stdin:
+        eprint("[python] received line: \"%s\"" % line.strip())
+        # reply (and flush immediately)
+        print("Python loves you, OCaml!", flush=True)
+    eprint("[python] input pipe closed; shuttind down...")
+    exit(0)
+
+if __name__ == '__main__':
+    main()

src/jbuild

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+(jbuild_version 1)
+
+(executable
+ ((name        main)
+  (public_name ocaml-python)
+  (libraries (
+    core
+    findlib
+  ))
+))

src/main.ml

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+open Core
+
+(* The name of this package. Ideally, should not be hard-coded. *)
+let pkg_name = "ocaml-python"
+
+(* The name of the python script to invoke. *)
+let script_name = "my-script.pyc"
+
+(* At runtime, we look for the python script in the opam library folder of our
+   package. *)
+let pyscript = match Findlib.package_directory pkg_name with
+  | dir ->
+    dir ^ "/" ^ script_name
+  | exception Findlib.No_such_package _ ->
+    failwith ("missing ocamlfind dependency: " ^ pkg_name)
+
+
+let () = begin
+  (* start Python 3 process *)
+  let cmd = "python3 " ^ pyscript in
+  let (from_py, to_py) = Unix.open_process cmd in
+
+  (* send some stuff to python *)
+  printf "[ocaml] sending message to python...\n%!";
+  (* force out_channel to flush immediately with `%!` *)
+  Out_channel.fprintf to_py
+    "Hi there, Python! This is 🐪. My favorite number is %d.\n%!" 42;
+
+  (* receive stuff from python *)
+  begin try while true do
+    (* receive one line at a time *)
+    printf "[ocaml] waiting for python response...\n%!";
+    let line = In_channel.input_line_exn from_py in
+
+    (* Do something with line! *)
+    (* As an example, we will just print the line to stdout and then close the
+       pipe to Python. *)
+     printf "[ocaml] received from Python: \"%s\"\n%!" line;
+
+     (* closing the pipe to Python will cause the script to terminate *)
+     Out_channel.close to_py;
+  done with
+    | End_of_file -> ()
+  end;
+
+  printf "[ocaml] All done. Bye bye!\n%!";
+end