asdf

serde/serde.ml

@@ -402,8 +402,9 @@ module rec De_base : sig
     visit_string : 'state De_base.ctx -> string -> ('value, error) result;
   }
 
-  val deserializer :
-    ('state De_base.ctx -> ('value, error) result) -> ('value, 'state) t
+  type 'value de = De : ('value, 'state) t -> 'value de
+
+  val deserializer : (('value, 'state) t) -> 'value de
 
   module type Deserializer = sig
     type state
@@ -499,7 +500,9 @@ end = struct
     visit_string : 'state De_base.ctx -> string -> ('value, error) result;
   }
 
-  let deserializer fn = fn
+  type 'value de = De : ('value, 'state) t -> 'value de
+
+  let deserializer fn = De fn
 
   module type Deserializer = sig
     type state
@@ -758,8 +761,5 @@ let serialize :
 
 let deserialize :
     type value state output.
-    state Deserializer.t ->
-    state ->
-    (value, state) De.t ->
-    (value, error) result =
- fun fmt ctx de -> de (fmt, ctx)
+    state Deserializer.t -> state -> value De.de -> (value, error) result =
+ fun fmt ctx (De de) -> de (Obj.magic fmt, Obj.magic ctx)

serde/serde_test.ml

@@ -474,7 +474,7 @@ let _serde_bin_roundtrip_tests =
       in
       deserializer @@ fun ctx ->
       record ctx "nested" 1 @@ fun _ctx ->
-      let* nested = field ctx "nested" (d nested_deserializer) in
+      let* nested = field ctx "nested" nested_deserializer in
       Ok { nested })
     { nested = { nested_flag = false } }
     {|({nested={nested_flag=false}})|};