I added the patching of sets.

Syntax: patch s with set ... end

AST.ml

@@ -333,6 +333,7 @@ and single_instr =
 | Skip        of kwd_skip
 | RecordPatch of record_patch reg
 | MapPatch    of map_patch reg
+| SetPatch    of set_patch reg
 | MapRemove   of map_remove reg
 | SetRemove   of set_remove reg
 
@@ -352,6 +353,13 @@ and map_remove = {
   map        : path
 }
 
+and set_patch  = {
+  kwd_patch : kwd_patch;
+  path      : path;
+  kwd_with  : kwd_with;
+  set_inj   : set_injection reg
+}
+
 and map_patch  = {
   kwd_patch : kwd_patch;
   path      : path;
@@ -721,6 +729,7 @@ let instr_to_region = function
 | Single Fail                {region; _}
 | Single RecordPatch         {region; _}
 | Single MapPatch            {region; _}
+| Single SetPatch            {region; _}
 | Single MapRemove           {region; _}
 | Single SetRemove           {region; _}
 | Block                      {region; _} -> region
@@ -1019,6 +1028,7 @@ and print_single_instr = function
 | Skip        kwd_skip   -> print_token kwd_skip "skip"
 | RecordPatch {value; _} -> print_record_patch value
 | MapPatch    {value; _} -> print_map_patch value
+| SetPatch    {value; _} -> print_set_patch value
 | MapRemove   {value; _} -> print_map_remove value
 | SetRemove   {value; _} -> print_set_remove value
 
@@ -1255,6 +1265,13 @@ and print_record_patch node =
   print_token kwd_with "with";
   print_record_injection record_inj
 
+and print_set_patch node =
+  let {kwd_patch; path; kwd_with; set_inj} = node in
+  print_token kwd_patch "patch";
+  print_path path;
+  print_token kwd_with "with";
+  print_set_injection set_inj
+
 and print_map_patch node =
   let {kwd_patch; path; kwd_with; map_inj} = node in
   print_token kwd_patch "patch";

AST.mli

@@ -317,6 +317,7 @@ and single_instr =
 | Skip        of kwd_skip
 | RecordPatch of record_patch reg
 | MapPatch    of map_patch reg
+| SetPatch    of set_patch reg
 | MapRemove   of map_remove reg
 | SetRemove   of set_remove reg
 
@@ -336,6 +337,13 @@ and map_remove = {
   map        : path
 }
 
+and set_patch  = {
+  kwd_patch : kwd_patch;
+  path      : path;
+  kwd_with  : kwd_with;
+  set_inj   : set_injection reg
+}
+
 and map_patch  = {
   kwd_patch : kwd_patch;
   path      : path;

Parser.mly

@@ -474,6 +474,7 @@ single_instr:
 | Skip         {        Skip $1 }
 | record_patch { RecordPatch $1 }
 | map_patch    {    MapPatch $1 }
+| set_patch    {    SetPatch $1 }
 | map_remove   {   MapRemove $1 }
 | set_remove   {   SetRemove $1 }
 
@@ -501,6 +502,17 @@ map_remove:
     in {region; value}
   }
 
+set_patch:
+  Patch path With set_injection {
+    let region = cover $1 $4.region in
+    let value  = {
+      kwd_patch = $1;
+      path      = $2;
+      kwd_with  = $3;
+      set_inj   = $4}
+    in {region; value}
+  }
+
 map_patch:
   Patch path With map_injection {
     let region = cover $1 $4.region in