Translate 'Lwt_unix.read_value' and 'write_value'

They are translated to corresponding blocking calls to Marshal. This
will most probably not type check as other IO functions are working on
either `Eio.Flow` or `Eio.Buf_read`.

Author: Julow

bin/lwt_to_direct_style/ast_rewrite.ml

@@ -318,6 +318,8 @@ let rewrite_apply ~backend ~state full_ident args =
       (( "socket" | "socketpair" | "listen" | "shutdown" | "getsockname"
        | "getpeername" | "waitpid" | "wait4" | "wait" ) as ident) ) ->
       transparent [ "Unix"; ident ]
+  | "Lwt_io", "read_value" -> transparent [ "Marshal"; "from_channel" ]
+  | "Lwt_io", "write_value" -> transparent [ "Marshal"; "to_channel" ]
   | "Lwt_unix", (("connect" | "accept" | "bind") as ident) ->
       Printf.ksprintf (add_comment state)
         "This call to [Unix.%s] was [Lwt_unix.%s] before. It's now blocking."

test/lwt_to_direct_style/to_direct_style.t/run.t

@@ -230,7 +230,7 @@ Make a writable directory tree:
     Lwt_mutex.lock (line 136 column 9)
     Lwt_mutex.unlock (line 137 column 9)
     Lwt_mutex.with_lock (line 138 column 9)
-  lib/test_lwt_unix.ml: (53 occurrences)
+  lib/test_lwt_unix.ml: (55 occurrences)
     Lwt_io (line 7 column 8)
     Lwt.return (line 12 column 3)
     Lwt.return (line 46 column 11)
@@ -259,8 +259,10 @@ Make a writable directory tree:
     Lwt_io.read (line 41 column 15)
     Lwt_io.read_into (line 10 column 21)
     Lwt_io.read_into_exactly (line 11 column 13)
+    Lwt_io.read_value (line 57 column 12)
     Lwt_io.flush (line 42 column 15)
     Lwt_io.write (line 24 column 19)
+    Lwt_io.write_value (line 58 column 14)
     Lwt_io.length (line 35 column 3)
     Lwt_io.stdin (line 25 column 32)
     Lwt_io.stdout (line 26 column 33)
@@ -861,3 +863,5 @@ Make a writable directory tree:
       a b
 
   let _f a b = Unix.listen a b
+  let _f a = Marshal.from_channel a
+  let _f a b = Marshal.to_channel a b

test/lwt_to_direct_style/to_direct_style.t/src/lib/test_lwt_unix.ml

@@ -53,3 +53,6 @@ let _f a b = Lwt_unix.connect a b
 let _f a = Lwt_unix.accept a
 let _f a b = Lwt_unix.bind a b
 let _f a b = Lwt_unix.listen a b
+
+let _f a = Lwt_io.read_value a
+let _f a b = Lwt_io.write_value a b