move external to private module, add some examples

examples/dune

@@ -1,3 +1,14 @@
 (executable
-  (name print_code)
-  (libraries exit))
+ (name print_code)
+ (modules print_code)
+ (libraries exit))
+
+(executable
+ (name exit_failure)
+ (modules exit_failure)
+ (libraries exit))
+
+(executable
+ (name exit_success)
+ (modules exit_success)
+ (libraries exit))

examples/exit_failure.ml

@@ -0,0 +1 @@
+let () = Exit.failure ()

examples/exit_success.ml

@@ -0,0 +1 @@
+let () = Exit.success ()

examples/print_code.ml

@@ -1,4 +1,4 @@
-let _ =
+let () =
   Format.printf "succes code is %d@." Exit.success_code ;
   Format.printf "failure code is %d@." Exit.failure_code ;
   if Exit.success_code <> 0 || Exit.failure_code <> 1 then (

src/dune

@@ -1,8 +1,10 @@
 (library
  (public_name exit)
+ (modules exit external)
+ (private_modules external)
  (wrapped false)
  (preprocess
-  (pps bisect_ppx -conditional))
+  (pps bisect_ppx -- --conditional))
  (foreign_stubs
   (language c)
   (names exit_stubs)))

src/exit.ml

@@ -1,10 +1,6 @@
-external success_code : unit -> int = "get_success_code"
+let success_code = External.success_code ()
 
-external failure_code : unit -> int = "get_failure_code"
-
-let success_code = success_code ()
-
-let failure_code = failure_code ()
+let failure_code = External.failure_code ()
 
 let success () = exit success_code
 

src/external.ml

@@ -0,0 +1,3 @@
+external failure_code : unit -> int = "get_failure_code"
+
+external success_code : unit -> int = "get_success_code"