add Syntax.list_filter_map

src/syntax.ml

@@ -7,8 +7,6 @@ let unwrap_err_msg o = match o with Error (`Msg e) -> Error e | Ok v -> Ok v
 let unwrap_err_caqti o =
   match o with Error err -> Fmt.error "%a" Caqti_error.pp err | Ok v -> Ok v
 
-(* TODO list_filter_map *)
-
 let list_iter f l =
   let err = ref None in
   try
@@ -37,6 +35,20 @@ let list_map f l =
          l)
   with Exit -> ( match !err with None -> assert false | Some v -> v)
 
+let list_filter_map f l =
+  let err = ref None in
+  try
+    Ok
+      (List.filter_map
+         (fun v ->
+           match f v with
+           | Error _e as e ->
+               err := Some e;
+               raise Exit
+           | Ok v -> v)
+         l)
+  with Exit -> ( match !err with None -> assert false | Some v -> v)
+
 let list_fold_left f acc l =
   List.fold_left
     (fun acc v ->