Trim empty lines upfront

bin/test/main.ml

@@ -182,14 +182,6 @@ let run_toplevel_tests ?root c ppf tests t =
     ) tests;
   Block.pp_footer ppf ()
 
-let trim l =
-  let rec trim_front = function
-    | ""::t -> trim_front t
-    | l -> l
-  in
-  let rev_trim l = trim_front (List.rev (trim_front l)) in
-  rev_trim (List.rev_map String.trim l)
-
 type file = { first: Mdx_top.Part.file; current: Mdx_top.Part.file }
 
 let files: (string, file) Hashtbl.t = Hashtbl.create 8
@@ -227,8 +219,8 @@ let update_block_with_file ppf t file part =
       (match part with None -> "" | Some p -> p)
       file
   | Some lines ->
-    let lines = trim lines in
     let contents = String.concat "\n" lines in
+    let contents = String.trim contents in
     Output.pp ppf (`Output contents);
     Block.pp_footer ppf ()
 

lib/top/part.ml

@@ -35,6 +35,9 @@ let rec remove_empty_heads = function
   | "" :: tl -> remove_empty_heads tl
   | l -> l
 
+let trim_empty_rev l =
+  remove_empty_heads (List.rev (remove_empty_heads l))
+
 module Parse_parts =
 struct
 
@@ -47,8 +50,8 @@ struct
       ws; str "]"; ws; opt (str ";;"); ws;
     ]
 
-  let next_part ~name ~sep_indent = fun lines ->
-    let body = String.concat "\n" (List.rev (remove_empty_heads lines)) in
+  let next_part ~name ~sep_indent = fun lines_rev ->
+    let body = String.concat "\n" (trim_empty_rev lines_rev) in
     Part.v ~name ~sep_indent ~body
 
   let next_part_of_groups groups =

test/sync_to_ml.ml.expected

@@ -19,6 +19,5 @@ let f = "hello world!"
 
 [@@@part "42"] ;;
 
-
 let () =
   f x print_int