diff --git a/src/clint.py b/src/clint.py
index e7d76366b0..4b7bf002e6 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -2544,6 +2544,7 @@ def CheckSpacing(filename, clean_lines, linenum, nesting_state, error):
                    r'(?<!\bPMap)'
                    r'(?<!\bArrayOf)'
                    r'(?<!\bDictionaryOf)'
+                   r'(?<!\bDict)'
                    r'\((?:const )?(?:struct )?[a-zA-Z_]\w*(?: *\*(?:const)?)*\)'
                    r' +'
                    r'-?(?:\*+|&)?(?:\w+|\+\+|--|\()', cast_line)
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index e35e7ce2d4..9c6eafa2df 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -27,6 +27,7 @@ set(BINARY_LIB_DIR ${PROJECT_BINARY_DIR}/lib/nvim/)
 set(API_DISPATCH_GENERATOR ${GENERATOR_DIR}/gen_api_dispatch.lua)
 set(API_UI_EVENTS_GENERATOR ${GENERATOR_DIR}/gen_api_ui_events.lua)
 set(GENERATOR_C_GRAMMAR ${GENERATOR_DIR}/c_grammar.lua)
+set(GENERATOR_HASHY ${GENERATOR_DIR}/hashy.lua)
 set(API_METADATA ${PROJECT_BINARY_DIR}/api_metadata.mpack)
 set(FUNCS_DATA ${PROJECT_BINARY_DIR}/funcs_data.mpack)
 set(LUA_API_C_BINDINGS ${GENERATED_DIR}/lua_api_c_bindings.generated.c)
@@ -42,12 +43,15 @@ set(GENERATED_UI_EVENTS_METADATA ${GENERATED_DIR}/api/private/ui_events_metadata
 set(GENERATED_EX_CMDS_ENUM ${GENERATED_INCLUDES_DIR}/ex_cmds_enum.generated.h)
 set(GENERATED_EX_CMDS_DEFS ${GENERATED_DIR}/ex_cmds_defs.generated.h)
 set(GENERATED_FUNCS ${GENERATED_DIR}/funcs.generated.h)
+set(GENERATED_KEYSETS ${GENERATED_DIR}/keysets.generated.h)
+set(GENERATED_KEYSETS_DEFS ${GENERATED_DIR}/keysets_defs.generated.h)
 set(GENERATED_EVENTS_ENUM ${GENERATED_INCLUDES_DIR}/auevents_enum.generated.h)
 set(GENERATED_EVENTS_NAMES_MAP ${GENERATED_DIR}/auevents_name_map.generated.h)
 set(GENERATED_OPTIONS ${GENERATED_DIR}/options.generated.h)
 set(EX_CMDS_GENERATOR ${GENERATOR_DIR}/gen_ex_cmds.lua)
 set(FUNCS_GENERATOR ${GENERATOR_DIR}/gen_eval.lua)
 set(EVENTS_GENERATOR ${GENERATOR_DIR}/gen_events.lua)
+set(KEYSETS_GENERATOR ${GENERATOR_DIR}/gen_keysets.lua)
 set(OPTIONS_GENERATOR ${GENERATOR_DIR}/gen_options.lua)
 set(UNICODE_TABLES_GENERATOR ${GENERATOR_DIR}/gen_unicode_tables.lua)
 set(UNICODE_DIR ${PROJECT_SOURCE_DIR}/unicode)
@@ -261,6 +265,7 @@ foreach(sfile ${NVIM_SOURCES}
               "${GENERATED_UI_EVENTS_CALL}"
               "${GENERATED_UI_EVENTS_REMOTE}"
               "${GENERATED_UI_EVENTS_BRIDGE}"
+              "${GENERATED_KEYSETS}"
               )
   get_filename_component(full_d ${sfile} PATH)
   file(RELATIVE_PATH d "${CMAKE_CURRENT_LIST_DIR}" "${full_d}")
@@ -364,12 +369,14 @@ add_custom_command(
 list(APPEND NVIM_GENERATED_FOR_HEADERS
   "${GENERATED_EX_CMDS_ENUM}"
   "${GENERATED_EVENTS_ENUM}"
+  "${GENERATED_KEYSETS_DEFS}"
 )
 
 list(APPEND NVIM_GENERATED_FOR_SOURCES
   "${GENERATED_API_DISPATCH}"
   "${GENERATED_EX_CMDS_DEFS}"
   "${GENERATED_EVENTS_NAMES_MAP}"
+  "${GENERATED_KEYSETS}"
   "${GENERATED_OPTIONS}"
   "${GENERATED_UNICODE_TABLES}"
   "${VIM_MODULE_FILE}"
@@ -404,6 +411,12 @@ add_custom_command(OUTPUT ${GENERATED_EVENTS_ENUM} ${GENERATED_EVENTS_NAMES_MAP}
   DEPENDS ${EVENTS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/auevents.lua
 )
 
+add_custom_command(OUTPUT ${GENERATED_KEYSETS} ${GENERATED_KEYSETS_DEFS}
+  COMMAND ${LUA_PRG} ${KEYSETS_GENERATOR}
+      ${CMAKE_CURRENT_LIST_DIR} ${LUA_SHARED_MODULE_SOURCE} ${GENERATED_KEYSETS} ${GENERATED_KEYSETS_DEFS}
+  DEPENDS ${KEYSETS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/api/keysets.lua ${GENERATOR_HASHY}
+)
+
 add_custom_command(OUTPUT ${GENERATED_OPTIONS}
   COMMAND ${LUA_PRG} ${OPTIONS_GENERATOR}
                      ${CMAKE_CURRENT_LIST_DIR} ${GENERATED_OPTIONS}
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 0ef2776263..34d7f6e32d 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -858,7 +858,7 @@ ArrayOf(Dictionary) nvim_buf_get_keymap(Buffer buffer, String mode, Error *err)
 /// @see |nvim_set_keymap()|
 ///
 /// @param  buffer  Buffer handle, or 0 for current buffer
-void nvim_buf_set_keymap(Buffer buffer, String mode, String lhs, String rhs, Dictionary opts,
+void nvim_buf_set_keymap(Buffer buffer, String mode, String lhs, String rhs, Dict(keymap) *opts,
                          Error *err)
   FUNC_API_SINCE(6)
 {
@@ -874,8 +874,7 @@ void nvim_buf_del_keymap(Buffer buffer, String mode, String lhs, Error *err)
   FUNC_API_SINCE(6)
 {
   String rhs = { .data = "", .size = 0 };
-  Dictionary opts = ARRAY_DICT_INIT;
-  modify_keymap(buffer, true, mode, lhs, rhs, opts, err);
+  modify_keymap(buffer, true, mode, lhs, rhs, NULL, err);
 }
 
 /// Gets a map of buffer-local |user-commands|.
@@ -885,22 +884,13 @@ void nvim_buf_del_keymap(Buffer buffer, String mode, String lhs, Error *err)
 /// @param[out]  err   Error details, if any.
 ///
 /// @returns Map of maps describing commands.
-Dictionary nvim_buf_get_commands(Buffer buffer, Dictionary opts, Error *err)
+Dictionary nvim_buf_get_commands(Buffer buffer, Dict(get_commands) *opts, Error *err)
   FUNC_API_SINCE(4)
 {
   bool global = (buffer == -1);
-  bool builtin = false;
-
-  for (size_t i = 0; i < opts.size; i++) {
-    String k = opts.items[i].key;
-    Object v = opts.items[i].value;
-    if (!strequal("builtin", k.data)) {
-      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
-      return (Dictionary)ARRAY_DICT_INIT;
-    }
-    if (strequal("builtin", k.data)) {
-      builtin = v.data.boolean;
-    }
+  bool builtin = api_object_to_bool(opts->builtin, "builtin", false, err);
+  if (ERROR_SET(err)) {
+    return (Dictionary)ARRAY_DICT_INIT;
   }
 
   if (global) {
@@ -1485,7 +1475,7 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 /// @param[out]  err   Error details, if any
 /// @return Id of the created/updated extmark
 Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer col,
-                             Dictionary opts, Error *err)
+                             Dict(set_extmark) *opts, Error *err)
   FUNC_API_SINCE(7)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -1498,211 +1488,174 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     return 0;
   }
 
-  bool ephemeral = false;
 
   uint64_t id = 0;
-  int line2 = -1;
-  Decoration decor = DECORATION_INIT;
-  colnr_T col2 = -1;
+  if (opts->id.type == kObjectTypeInteger && opts->id.data.integer > 0) {
+    id = (uint64_t)opts->id.data.integer;
+  } else if (HAS_KEY(opts->id)) {
+      api_set_error(err, kErrorTypeValidation, "id is not a positive integer");
+      goto error;
+  }
 
-  bool right_gravity = true;
-  bool end_right_gravity = false;
-  bool end_gravity_set = false;
+  int line2 = -1;
+  if (opts->end_line.type == kObjectTypeInteger) {
+    Integer val = opts->end_line.data.integer;
+    if (val < 0 || val > buf->b_ml.ml_line_count) {
+      api_set_error(err, kErrorTypeValidation, "end_line value outside range");
+      goto error;
+    } else {
+      line2 = (int)val;
+    }
+  } else if (HAS_KEY(opts->end_line)) {
+    api_set_error(err, kErrorTypeValidation, "end_line is not an integer");
+    goto error;
+  }
+
+  colnr_T col2 = -1;
+  if (opts->end_col.type == kObjectTypeInteger) {
+    Integer val = opts->end_col.data.integer;
+    if (val < 0 || val > MAXCOL) {
+      api_set_error(err, kErrorTypeValidation, "end_col value outside range");
+      goto error;
+    } else {
+      col2 = (int)val;
+    }
+  } else if (HAS_KEY(opts->end_col)) {
+    api_set_error(err, kErrorTypeValidation, "end_col is not an integer");
+    goto error;
+  }
+
+  Decoration decor = DECORATION_INIT;
+
+  if (HAS_KEY(opts->hl_group)) {
+    decor.hl_id = object_to_hl_id(opts->hl_group, "hl_group", err);
+    if (ERROR_SET(err)) {
+      goto error;
+    }
+  }
+
+  if (opts->virt_text.type == kObjectTypeArray) {
+    decor.virt_text = parse_virt_text(opts->virt_text.data.array, err,
+                                      &decor.virt_text_width);
+    if (ERROR_SET(err)) {
+      goto error;
+    }
+  } else if (HAS_KEY(opts->virt_text)) {
+    api_set_error(err, kErrorTypeValidation, "virt_text is not an Array");
+    goto error;
+  }
+
+  if (opts->virt_text_pos.type == kObjectTypeString) {
+    String str = opts->virt_text_pos.data.string;
+    if (strequal("eol", str.data)) {
+      decor.virt_text_pos = kVTEndOfLine;
+    } else if (strequal("overlay", str.data)) {
+      decor.virt_text_pos = kVTOverlay;
+    } else if (strequal("right_align", str.data)) {
+      decor.virt_text_pos = kVTRightAlign;
+    } else {
+      api_set_error(err, kErrorTypeValidation, "virt_text_pos: invalid value");
+      goto error;
+    }
+  } else if (HAS_KEY(opts->virt_text_pos)) {
+    api_set_error(err, kErrorTypeValidation, "virt_text_pos is not a String");
+    goto error;
+  }
+
+  if (opts->virt_text_win_col.type == kObjectTypeInteger) {
+    decor.col = (int)opts->virt_text_win_col.data.integer;
+    decor.virt_text_pos = kVTWinCol;
+  } else if (HAS_KEY(opts->virt_text_win_col)) {
+    api_set_error(err, kErrorTypeValidation,
+                  "virt_text_win_col is not a Number of the correct size");
+    goto error;
+  }
+
+#define OPTION_TO_BOOL(target, name, val) \
+    target = api_object_to_bool(opts-> name, #name, val, err); \
+    if (ERROR_SET(err)) { \
+      goto error; \
+    }
+
+  OPTION_TO_BOOL(decor.virt_text_hide, virt_text_hide, false);
+  OPTION_TO_BOOL(decor.hl_eol, hl_eol, false);
+
+  if (opts->hl_mode.type == kObjectTypeString) {
+    String str = opts->hl_mode.data.string;
+    if (strequal("replace", str.data)) {
+      decor.hl_mode = kHlModeReplace;
+    } else if (strequal("combine", str.data)) {
+      decor.hl_mode = kHlModeCombine;
+    } else if (strequal("blend", str.data)) {
+      decor.hl_mode = kHlModeBlend;
+    } else {
+      api_set_error(err, kErrorTypeValidation,
+                    "virt_text_pos: invalid value");
+      goto error;
+    }
+  } else if (HAS_KEY(opts->hl_mode)) {
+    api_set_error(err, kErrorTypeValidation, "hl_mode is not a String");
+    goto error;
+  }
 
   VirtLines virt_lines = KV_INITIAL_VALUE;
   bool virt_lines_above = false;
   bool virt_lines_leftcol = false;
 
-  for (size_t i = 0; i < opts.size; i++) {
-    String k = opts.items[i].key;
-    Object *v = &opts.items[i].value;
-    if (strequal("id", k.data)) {
-      if (v->type != kObjectTypeInteger || v->data.integer <= 0) {
-        api_set_error(err, kErrorTypeValidation,
-                      "id is not a positive integer");
+  if (opts->virt_lines.type == kObjectTypeArray) {
+    Array a = opts->virt_lines.data.array;
+    for (size_t j = 0; j < a.size; j++) {
+      if (a.items[j].type != kObjectTypeArray) {
+        api_set_error(err, kErrorTypeValidation, "virt_text_line item is not an Array");
         goto error;
       }
-
-      id = (uint64_t)v->data.integer;
-    } else if (strequal("end_line", k.data)) {
-      if (v->type != kObjectTypeInteger) {
-        api_set_error(err, kErrorTypeValidation,
-                      "end_line is not an integer");
-        goto error;
-      }
-      if (v->data.integer < 0 || v->data.integer > buf->b_ml.ml_line_count) {
-        api_set_error(err, kErrorTypeValidation,
-                      "end_line value outside range");
-        goto error;
-      }
-
-      line2 = (int)v->data.integer;
-    } else if (strequal("end_col", k.data)) {
-      if (v->type != kObjectTypeInteger) {
-        api_set_error(err, kErrorTypeValidation,
-                      "end_col is not an integer");
-        goto error;
-      }
-      if (v->data.integer < 0 || v->data.integer > MAXCOL) {
-        api_set_error(err, kErrorTypeValidation,
-                      "end_col value outside range");
-        goto error;
-      }
-
-      col2 = (colnr_T)v->data.integer;
-    } else if (strequal("hl_group", k.data)) {
-      String hl_group;
-      switch (v->type) {
-      case kObjectTypeString:
-        hl_group = v->data.string;
-        decor.hl_id = syn_check_group((char_u *)(hl_group.data),
-                                      (int)hl_group.size);
-        break;
-      case kObjectTypeInteger:
-        decor.hl_id = (int)v->data.integer;
-        break;
-      default:
-        api_set_error(err, kErrorTypeValidation,
-                      "hl_group is not valid.");
-        goto error;
-      }
-    } else if (strequal("virt_text", k.data)) {
-      if (v->type != kObjectTypeArray) {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_text is not an Array");
-        goto error;
-      }
-      decor.virt_text = parse_virt_text(v->data.array, err,
-                                        &decor.virt_text_width);
+      int dummig;
+      VirtText jtem = parse_virt_text(a.items[j].data.array, err, &dummig);
+      kv_push(virt_lines, jtem);
       if (ERROR_SET(err)) {
         goto error;
       }
-    } else if (strequal("virt_text_pos", k.data)) {
-      if (v->type != kObjectTypeString) {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_text_pos is not a String");
-        goto error;
-      }
-      String str = v->data.string;
-      if (strequal("eol", str.data)) {
-        decor.virt_text_pos = kVTEndOfLine;
-      } else if (strequal("overlay", str.data)) {
-        decor.virt_text_pos = kVTOverlay;
-      } else if (strequal("right_align", str.data)) {
-        decor.virt_text_pos = kVTRightAlign;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_text_pos: invalid value");
-        goto error;
-      }
-    } else if (strequal("virt_text_win_col",  k.data)) {
-      if (v->type != kObjectTypeInteger) {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_text_win_col is not a Number of the correct size");
-        goto error;
-      }
-
-      decor.col = (int)v->data.integer;
-      decor.virt_text_pos = kVTWinCol;
-    } else if (strequal("virt_text_hide", k.data)) {
-      decor.virt_text_hide = api_object_to_bool(*v,
-                                                "virt_text_hide", false, err);
-      if (ERROR_SET(err)) {
-        goto error;
-      }
-    } else if (strequal("virt_lines", k.data)) {
-      if (v->type != kObjectTypeArray) {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_lines is not an Array");
-        goto error;
-      }
-      Array a = v->data.array;
-      for (size_t j = 0; j < a.size; j++) {
-        if (a.items[j].type != kObjectTypeArray) {
-          api_set_error(err, kErrorTypeValidation,
-                        "virt_text_line item is not an Array");
-          goto error;
-        }
-        int dummig;
-        VirtText jtem = parse_virt_text(a.items[j].data.array, err, &dummig);
-        kv_push(virt_lines, jtem);
-        if (ERROR_SET(err)) {
-          goto error;
-        }
-      }
-    } else if (strequal("virt_lines_above", k.data)) {
-      virt_lines_above = api_object_to_bool(*v, "virt_lines_above", false, err);
-      if (ERROR_SET(err)) {
-        goto error;
-      }
-    } else if (strequal("virt_lines_leftcol", k.data)) {
-      virt_lines_leftcol = api_object_to_bool(*v, "virt_lines_leftcol", false, err);
-      if (ERROR_SET(err)) {
-        goto error;
-      }
-    } else if (strequal("hl_eol", k.data)) {
-      decor.hl_eol = api_object_to_bool(*v, "hl_eol", false, err);
-      if (ERROR_SET(err)) {
-        goto error;
-      }
-    } else if (strequal("hl_mode", k.data)) {
-      if (v->type != kObjectTypeString) {
-        api_set_error(err, kErrorTypeValidation,
-                      "hl_mode is not a String");
-        goto error;
-      }
-      String str = v->data.string;
-      if (strequal("replace", str.data)) {
-        decor.hl_mode = kHlModeReplace;
-      } else if (strequal("combine", str.data)) {
-        decor.hl_mode = kHlModeCombine;
-      } else if (strequal("blend", str.data)) {
-        decor.hl_mode = kHlModeBlend;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "virt_text_pos: invalid value");
-        goto error;
-      }
-    } else if (strequal("ephemeral", k.data)) {
-      ephemeral = api_object_to_bool(*v, "ephemeral", false, err);
-      if (ERROR_SET(err)) {
-        goto error;
-      }
-    } else if (strequal("priority",  k.data)) {
-      if (v->type != kObjectTypeInteger) {
-        api_set_error(err, kErrorTypeValidation,
-                      "priority is not a Number of the correct size");
-        goto error;
-      }
-
-      if (v->data.integer < 0 || v->data.integer > UINT16_MAX) {
-        api_set_error(err, kErrorTypeValidation,
-                      "priority is not a valid value");
-        goto error;
-      }
-      decor.priority = (DecorPriority)v->data.integer;
-    } else if (strequal("right_gravity", k.data)) {
-      if (v->type != kObjectTypeBoolean) {
-        api_set_error(err, kErrorTypeValidation,
-                      "right_gravity must be a boolean");
-        goto error;
-      }
-      right_gravity = v->data.boolean;
-    } else if (strequal("end_right_gravity", k.data)) {
-      if (v->type != kObjectTypeBoolean) {
-        api_set_error(err, kErrorTypeValidation,
-                      "end_right_gravity must be a boolean");
-        goto error;
-      }
-      end_right_gravity = v->data.boolean;
-      end_gravity_set = true;
-    } else {
-      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
-      goto error;
     }
+  } else if (HAS_KEY(opts->virt_lines)) {
+    api_set_error(err, kErrorTypeValidation, "virt_lines is not an Array");
+    goto error;
   }
 
+  OPTION_TO_BOOL(virt_lines_above, virt_lines_above, false);
+  OPTION_TO_BOOL(virt_lines_leftcol, virt_lines_leftcol, false);
+
+  if (opts->priority.type == kObjectTypeInteger) {
+    Integer val = opts->priority.data.integer;
+
+    if (val < 0 || val > UINT16_MAX) {
+      api_set_error(err, kErrorTypeValidation, "priority is not a valid value");
+      goto error;
+    }
+    decor.priority = (DecorPriority)val;
+  } else if (HAS_KEY(opts->priority)) {
+    api_set_error(err, kErrorTypeValidation, "priority is not a Number of the correct size");
+    goto error;
+  }
+
+  bool right_gravity = true;
+  OPTION_TO_BOOL(right_gravity, right_gravity, true);
+
+  // Only error out if they try to set end_right_gravity without
+  // setting end_col or end_line
+  if (line2 == -1 && col2 == -1 && HAS_KEY(opts->end_right_gravity)) {
+    api_set_error(err, kErrorTypeValidation,
+                  "cannot set end_right_gravity without setting end_line or end_col");
+    goto error;
+  }
+
+  bool end_right_gravity = false;
+  OPTION_TO_BOOL(end_right_gravity, end_right_gravity, false);
+
   size_t len = 0;
+
+  bool ephemeral = false;
+  OPTION_TO_BOOL(ephemeral, ephemeral, false);
+
   if (line < 0 || line > buf->b_ml.ml_line_count) {
     api_set_error(err, kErrorTypeValidation, "line value outside range");
     return 0;
@@ -1717,15 +1670,6 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     return 0;
   }
 
-
-  // Only error out if they try to set end_right_gravity without
-  // setting end_col or end_line
-  if (line2 == -1 && col2 == -1 && end_gravity_set) {
-    api_set_error(err, kErrorTypeValidation,
-                  "cannot set end_right_gravity "
-                  "without setting end_line or end_col");
-  }
-
   if (col2 >= 0) {
     if (line2 >= 0 && line2 < buf->b_ml.ml_line_count) {
       len = ephemeral ? MAXCOL : STRLEN(ml_get_buf(buf, (linenr_T)line2 + 1, false));
@@ -1744,15 +1688,6 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     col2 = 0;
   }
 
-  if (decor.virt_text_pos == kVTRightAlign) {
-    decor.col = 0;
-    for (size_t i = 0; i < kv_size(decor.virt_text); i++) {
-      decor.col
-        += (int)mb_string2cells((char_u *)kv_A(decor.virt_text, i).text);
-    }
-  }
-
-
   Decoration *d = NULL;
 
   if (ephemeral) {
diff --git a/src/nvim/api/keysets.lua b/src/nvim/api/keysets.lua
new file mode 100644
index 0000000000..76ce9e15ea
--- /dev/null
+++ b/src/nvim/api/keysets.lua
@@ -0,0 +1,52 @@
+return {
+  context = {
+    "types";
+  };
+  set_extmark = {
+    "id";
+    "end_line";
+    "end_col";
+    "hl_group";
+    "virt_text";
+    "virt_text_pos";
+    "virt_text_win_col";
+    "virt_text_hide";
+    "hl_eol";
+    "hl_mode";
+    "ephemeral";
+    "priority";
+    "right_gravity";
+    "end_right_gravity";
+    "virt_lines";
+    "virt_lines_above";
+    "virt_lines_leftcol";
+  };
+  keymap = {
+    "noremap";
+    "nowait";
+    "silent";
+    "script";
+    "expr";
+    "unique";
+  };
+  get_commands = {
+    "builtin";
+  };
+  float_config = {
+    "row";
+    "col";
+    "width";
+    "height";
+    "anchor";
+    "relative";
+    "win";
+    "bufpos";
+    "external";
+    "focusable";
+    "zindex";
+    "border";
+    "style";
+    "noautocmd";
+  };
+}
+
diff --git a/src/nvim/api/private/defs.h b/src/nvim/api/private/defs.h
index f0d48bf145..8346e01558 100644
--- a/src/nvim/api/private/defs.h
+++ b/src/nvim/api/private/defs.h
@@ -19,6 +19,7 @@
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # define ArrayOf(...) Array
 # define DictionaryOf(...) Dictionary
+# define Dict(name) KeyDict_##name
 #endif
 
 // Basic types
@@ -129,5 +130,14 @@ struct key_value_pair {
   Object value;
 };
 
+typedef Object *(*field_hash)(void *retval, const char *str, size_t len);
+typedef struct {
+  char *str;
+  size_t ptr_off;
+} KeySetLink;
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "keysets_defs.generated.h"
+#endif
 
 #endif  // NVIM_API_PRIVATE_DEFS_H
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 193f1dd572..24fac0a916 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -6,6 +6,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stddef.h>
 
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
@@ -814,7 +815,7 @@ Array string_to_array(const String input, bool crlf)
 ///                   buffer, or -1 to signify global behavior ("all buffers")
 /// @param  is_unmap  When true, removes the mapping that matches {lhs}.
 void modify_keymap(Buffer buffer, bool is_unmap, String mode, String lhs, String rhs,
-                   Dictionary opts, Error *err)
+                   Dict(keymap) *opts, Error *err)
 {
   char *err_msg = NULL;  // the error message to report, if any
   char *err_arg = NULL;  // argument for the error message format string
@@ -833,10 +834,21 @@ void modify_keymap(Buffer buffer, bool is_unmap, String mode, String lhs, String
     return;
   }
 
-  MapArguments parsed_args;
-  memset(&parsed_args, 0, sizeof(parsed_args));
-  if (parse_keymap_opts(opts, &parsed_args, err)) {
-    goto fail_and_free;
+  MapArguments parsed_args = MAP_ARGUMENTS_INIT;
+  if (opts) {
+#define KEY_TO_BOOL(name) \
+    parsed_args. name = api_object_to_bool(opts-> name, #name, false, err); \
+    if (ERROR_SET(err)) { \
+      goto fail_and_free; \
+    }
+
+    KEY_TO_BOOL(nowait);
+    KEY_TO_BOOL(noremap);
+    KEY_TO_BOOL(silent);
+    KEY_TO_BOOL(script);
+    KEY_TO_BOOL(expr);
+    KEY_TO_BOOL(unique);
+#undef KEY_TO_BOOL
   }
   parsed_args.buffer = !global;
 
@@ -947,95 +959,6 @@ fail_and_free:
   return;
 }
 
-/// Read in the given opts, setting corresponding flags in `out`.
-///
-/// @param opts A dictionary passed to @ref nvim_set_keymap or
-///             @ref nvim_buf_set_keymap.
-/// @param[out]   out  MapArguments object in which to set parsed
-///                    |:map-arguments| flags.
-/// @param[out]   err  Error details, if any.
-///
-/// @returns Zero on success, nonzero on failure.
-Integer parse_keymap_opts(Dictionary opts, MapArguments *out, Error *err)
-{
-  char *err_msg = NULL;  // the error message to report, if any
-  char *err_arg = NULL;  // argument for the error message format string
-  ErrorType err_type = kErrorTypeNone;
-
-  out->buffer = false;
-  out->nowait = false;
-  out->silent = false;
-  out->script = false;
-  out->expr = false;
-  out->unique = false;
-
-  for (size_t i = 0; i < opts.size; i++) {
-    KeyValuePair *key_and_val = &opts.items[i];
-    char *optname = key_and_val->key.data;
-
-    if (key_and_val->value.type != kObjectTypeBoolean) {
-      err_msg = "Gave non-boolean value for an opt: %s";
-      err_arg = optname;
-      err_type = kErrorTypeValidation;
-      goto fail_with_message;
-    }
-
-    bool was_valid_opt = false;
-    switch (optname[0]) {
-    // note: strncmp up to and including the null terminator, so that
-    // "nowaitFoobar" won't match against "nowait"
-
-    // don't recognize 'buffer' as a key; user shouldn't provide <buffer>
-    // when calling nvim_set_keymap or nvim_buf_set_keymap, since it can be
-    // inferred from which function they called
-    case 'n':
-      if (STRNCMP(optname, "noremap", 8) == 0) {
-        was_valid_opt = true;
-        out->noremap = key_and_val->value.data.boolean;
-      } else if (STRNCMP(optname, "nowait", 7) == 0) {
-        was_valid_opt = true;
-        out->nowait = key_and_val->value.data.boolean;
-      }
-      break;
-    case 's':
-      if (STRNCMP(optname, "silent", 7) == 0) {
-        was_valid_opt = true;
-        out->silent = key_and_val->value.data.boolean;
-      } else if (STRNCMP(optname, "script", 7) == 0) {
-        was_valid_opt = true;
-        out->script = key_and_val->value.data.boolean;
-      }
-      break;
-    case 'e':
-      if (STRNCMP(optname, "expr", 5) == 0) {
-        was_valid_opt = true;
-        out->expr = key_and_val->value.data.boolean;
-      }
-      break;
-    case 'u':
-      if (STRNCMP(optname, "unique", 7) == 0) {
-        was_valid_opt = true;
-        out->unique = key_and_val->value.data.boolean;
-      }
-      break;
-    default:
-      break;
-    }  // switch
-    if (!was_valid_opt) {
-      err_msg = "Invalid key: %s";
-      err_arg = optname;
-      err_type = kErrorTypeValidation;
-      goto fail_with_message;
-    }
-  }  // for
-
-  return 0;
-
-fail_with_message:
-  api_set_error(err, err_type, err_msg, err_arg);
-  return 1;
-}
-
 /// Collects `n` buffer lines into array `l`, optionally replacing newlines
 /// with NUL.
 ///
@@ -1879,213 +1802,227 @@ static void parse_border_style(Object style, FloatConfig *fconfig, Error *err)
   }
 }
 
-bool parse_float_config(Dictionary config, FloatConfig *fconfig, bool reconf, bool new_win,
+bool parse_float_config(Dict(float_config) *config, FloatConfig *fconfig, bool reconf, bool new_win,
                         Error *err)
 {
-  // TODO(bfredl): use a get/has_key interface instead and get rid of extra
-  // flags
-  bool has_row = false, has_col = false, has_relative = false;
-  bool has_external = false, has_window = false;
-  bool has_width = false, has_height = false;
-  bool has_bufpos = false;
+  bool has_relative = false, relative_is_win = false;
+  if (config->relative.type == kObjectTypeString) {
+    // ignore empty string, to match nvim_win_get_config
+    if (config->relative.data.string.size > 0) {
+      if (!parse_float_relative(config->relative.data.string, &fconfig->relative)) {
+        api_set_error(err, kErrorTypeValidation, "Invalid value of 'relative' key");
+        return false;
+      }
 
-  for (size_t i = 0; i < config.size; i++) {
-    char *key = config.items[i].key.data;
-    Object val = config.items[i].value;
-    if (!strcmp(key, "row")) {
-      has_row = true;
-      if (val.type == kObjectTypeInteger) {
-        fconfig->row = (double)val.data.integer;
-      } else if (val.type == kObjectTypeFloat) {
-        fconfig->row = val.data.floating;
-      } else {
+      if (!(HAS_KEY(config->row) && HAS_KEY(config->col)) && !HAS_KEY(config->bufpos)) {
         api_set_error(err, kErrorTypeValidation,
-                      "'row' key must be Integer or Float");
+                      "'relative' requires 'row'/'col' or 'bufpos'");
         return false;
       }
-    } else if (!strcmp(key, "col")) {
-      has_col = true;
-      if (val.type == kObjectTypeInteger) {
-        fconfig->col = (double)val.data.integer;
-      } else if (val.type == kObjectTypeFloat) {
-        fconfig->col = val.data.floating;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "'col' key must be Integer or Float");
-        return false;
-      }
-    } else if (strequal(key, "width")) {
-      has_width = true;
-      if (val.type == kObjectTypeInteger && val.data.integer > 0) {
-        fconfig->width = (int)val.data.integer;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "'width' key must be a positive Integer");
-        return false;
-      }
-    } else if (strequal(key, "height")) {
-      has_height = true;
-      if (val.type == kObjectTypeInteger && val.data.integer > 0) {
-        fconfig->height = (int)val.data.integer;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "'height' key must be a positive Integer");
-        return false;
-      }
-    } else if (!strcmp(key, "anchor")) {
-      if (val.type != kObjectTypeString) {
-        api_set_error(err, kErrorTypeValidation,
-                      "'anchor' key must be String");
-        return false;
-      }
-      if (!parse_float_anchor(val.data.string, &fconfig->anchor)) {
-        api_set_error(err, kErrorTypeValidation,
-                      "Invalid value of 'anchor' key");
-        return false;
-      }
-    } else if (!strcmp(key, "relative")) {
-      if (val.type != kObjectTypeString) {
-        api_set_error(err, kErrorTypeValidation,
-                      "'relative' key must be String");
-        return false;
-      }
-      // ignore empty string, to match nvim_win_get_config
-      if (val.data.string.size > 0) {
-        has_relative = true;
-        if (!parse_float_relative(val.data.string, &fconfig->relative)) {
-          api_set_error(err, kErrorTypeValidation,
-                        "Invalid value of 'relative' key");
-          return false;
-        }
-      }
-    } else if (!strcmp(key, "win")) {
-      has_window = true;
-      if (val.type != kObjectTypeInteger
-          && val.type != kObjectTypeWindow) {
-        api_set_error(err, kErrorTypeValidation,
-                      "'win' key must be Integer or Window");
-        return false;
-      }
-      fconfig->window = (Window)val.data.integer;
-    } else if (!strcmp(key, "bufpos")) {
-      if (val.type != kObjectTypeArray) {
-        api_set_error(err, kErrorTypeValidation,
-                      "'bufpos' key must be Array");
-        return false;
-      }
-      if (!parse_float_bufpos(val.data.array, &fconfig->bufpos)) {
-        api_set_error(err, kErrorTypeValidation,
-                      "Invalid value of 'bufpos' key");
-        return false;
-      }
-      has_bufpos = true;
-    } else if (!strcmp(key, "external")) {
-      has_external = fconfig->external
-                       = api_object_to_bool(val, "'external' key", false, err);
-      if (ERROR_SET(err)) {
-        return false;
-      }
-    } else if (!strcmp(key, "focusable")) {
-      fconfig->focusable
-        = api_object_to_bool(val, "'focusable' key", true, err);
-      if (ERROR_SET(err)) {
-        return false;
-      }
-    } else if (strequal(key, "zindex")) {
-      if (val.type == kObjectTypeInteger && val.data.integer > 0) {
-        fconfig->zindex = (int)val.data.integer;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "'zindex' key must be a positive Integer");
-        return false;
-      }
-    } else if (!strcmp(key, "border")) {
-      parse_border_style(val, fconfig, err);
-      if (ERROR_SET(err)) {
-        return false;
-      }
-    } else if (!strcmp(key, "style")) {
-      if (val.type != kObjectTypeString) {
-        api_set_error(err, kErrorTypeValidation,
-                      "'style' key must be String");
-        return false;
-      }
-      if (val.data.string.data[0] == NUL) {
-        fconfig->style = kWinStyleUnused;
-      } else if (striequal(val.data.string.data, "minimal")) {
-        fconfig->style = kWinStyleMinimal;
-      } else {
-        api_set_error(err, kErrorTypeValidation,
-                      "Invalid value of 'style' key");
-      }
-    } else if (strequal(key, "noautocmd") && new_win) {
-      fconfig->noautocmd
-        = api_object_to_bool(val, "'noautocmd' key", false, err);
-      if (ERROR_SET(err)) {
-        return false;
+
+      has_relative = true;
+      fconfig->external = false;
+      if (fconfig->relative == kFloatRelativeWindow) {
+        relative_is_win = true;
+        fconfig->bufpos.lnum = -1;
       }
+    }
+  } else if (HAS_KEY(config->relative)) {
+    api_set_error(err, kErrorTypeValidation, "'relative' key must be String");
+    return false;
+  }
+
+  if (config->anchor.type == kObjectTypeString) {
+    if (!parse_float_anchor(config->anchor.data.string, &fconfig->anchor)) {
+      api_set_error(err, kErrorTypeValidation, "Invalid value of 'anchor' key");
+      return false;
+    }
+  } else if (HAS_KEY(config->anchor)) {
+    api_set_error(err, kErrorTypeValidation, "'anchor' key must be String");
+    return false;
+  }
+
+  if (HAS_KEY(config->row)) {
+    if (!has_relative) {
+      api_set_error(err, kErrorTypeValidation, "non-float cannot have 'row'");
+      return false;
+    } else if (config->row.type == kObjectTypeInteger) {
+      fconfig->row = (double)config->row.data.integer;
+    } else if (config->row.type == kObjectTypeFloat) {
+      fconfig->row = config->row.data.floating;
     } else {
       api_set_error(err, kErrorTypeValidation,
-                    "Invalid key '%s'", key);
+                    "'row' key must be Integer or Float");
       return false;
     }
   }
 
-  if (has_window && !(has_relative
-                      && fconfig->relative == kFloatRelativeWindow)) {
-    api_set_error(err, kErrorTypeValidation,
-                  "'win' key is only valid with relative='win'");
+  if (HAS_KEY(config->col)) {
+    if (!has_relative) {
+      api_set_error(err, kErrorTypeValidation, "non-float cannot have 'col'");
+      return false;
+    } else if (config->col.type == kObjectTypeInteger) {
+      fconfig->col = (double)config->col.data.integer;
+    } else if (config->col.type == kObjectTypeFloat) {
+      fconfig->col = config->col.data.floating;
+    } else {
+      api_set_error(err, kErrorTypeValidation,
+                    "'col' key must be Integer or Float");
+      return false;
+    }
+  }
+
+  if (HAS_KEY(config->bufpos)) {
+    if (!has_relative) {
+      api_set_error(err, kErrorTypeValidation, "non-float cannot have 'bufpos'");
+      return false;
+    } else if (config->bufpos.type == kObjectTypeArray) {
+      if (!parse_float_bufpos(config->bufpos.data.array, &fconfig->bufpos)) {
+        api_set_error(err, kErrorTypeValidation, "Invalid value of 'bufpos' key");
+        return false;
+      }
+
+      if (!HAS_KEY(config->row)) {
+        fconfig->row = (fconfig->anchor & kFloatAnchorSouth) ? 0 : 1;
+      }
+      if (!HAS_KEY(config->col)) {
+        fconfig->col = 0;
+      }
+    } else {
+      api_set_error(err, kErrorTypeValidation, "'bufpos' key must be Array");
+      return false;
+    }
+  }
+
+  if (config->width.type == kObjectTypeInteger && config->width.data.integer > 0) {
+    fconfig->width = (int)config->width.data.integer;
+  } else if (HAS_KEY(config->width)) {
+    api_set_error(err, kErrorTypeValidation, "'width' key must be a positive Integer");
+    return false;
+  } else if (!reconf) {
+    api_set_error(err, kErrorTypeValidation, "Must specify 'width'");
     return false;
   }
 
-  if ((has_relative && fconfig->relative == kFloatRelativeWindow)
-      && (!has_window || fconfig->window == 0)) {
+  if (config->height.type == kObjectTypeInteger && config->height.data.integer > 0) {
+    fconfig->height = (int)config->height.data.integer;
+  } else if (HAS_KEY(config->height)) {
+    api_set_error(err, kErrorTypeValidation, "'height' key must be a positive Integer");
+    return false;
+  } else if (!reconf) {
+    api_set_error(err, kErrorTypeValidation, "Must specify 'height'");
+    return false;
+  }
+
+  if (relative_is_win) {
     fconfig->window = curwin->handle;
-  }
-
-  if (has_window && !has_bufpos) {
-    fconfig->bufpos.lnum = -1;
-  }
-
-  if (has_bufpos) {
-    if (!has_row) {
-      fconfig->row = (fconfig->anchor & kFloatAnchorSouth) ? 0 : 1;
-      has_row = true;
+    if (config->win.type == kObjectTypeInteger || config->win.type == kObjectTypeWindow) {
+      if (config->win.data.integer > 0) {
+        fconfig->window = (Window)config->win.data.integer;
+      }
+    } else if (HAS_KEY(config->win)) {
+      api_set_error(err, kErrorTypeValidation, "'win' key must be Integer or Window");
+      return false;
     }
-    if (!has_col) {
-      fconfig->col = 0;
-      has_col = true;
+  } else {
+    if (HAS_KEY(config->win)) {
+      api_set_error(err, kErrorTypeValidation, "'win' key is only valid with relative='win'");
+      return false;
     }
   }
 
-  if (has_relative && has_external) {
-    api_set_error(err, kErrorTypeValidation,
-                  "Only one of 'relative' and 'external' must be used");
-    return false;
-  } else if (!reconf && !has_relative && !has_external) {
+  if (HAS_KEY(config->external)) {
+    fconfig->external = api_object_to_bool(config->external, "'external' key", false, err);
+    if (ERROR_SET(err)) {
+      return false;
+    }
+    if (has_relative && fconfig->external) {
+      api_set_error(err, kErrorTypeValidation,
+                    "Only one of 'relative' and 'external' must be used");
+      return false;
+    }
+    if (fconfig->external && !ui_has(kUIMultigrid)) {
+      api_set_error(err, kErrorTypeValidation,
+                    "UI doesn't support external windows");
+      return false;
+    }
+  }
+
+  if (!reconf && (!has_relative && !fconfig->external)) {
     api_set_error(err, kErrorTypeValidation,
                   "One of 'relative' and 'external' must be used");
     return false;
-  } else if (has_relative) {
-    fconfig->external = false;
   }
 
-  if (!reconf && !(has_height && has_width)) {
-    api_set_error(err, kErrorTypeValidation,
-                  "Must specify 'width' and 'height'");
+
+  if (HAS_KEY(config->focusable)) {
+    fconfig->focusable = api_object_to_bool(config->focusable, "'focusable' key", false, err);
+    if (ERROR_SET(err)) {
+      return false;
+    }
+  }
+
+  if (config->zindex.type == kObjectTypeInteger && config->zindex.data.integer > 0) {
+    fconfig->zindex = (int)config->zindex.data.integer;
+  } else if (HAS_KEY(config->zindex)) {
+    api_set_error(err, kErrorTypeValidation, "'zindex' key must be a positive Integer");
     return false;
   }
 
-  if (fconfig->external && !ui_has(kUIMultigrid)) {
-    api_set_error(err, kErrorTypeValidation,
-                  "UI doesn't support external windows");
+  if (HAS_KEY(config->border)) {
+    parse_border_style(config->border, fconfig, err);
+    if (ERROR_SET(err)) {
+      return false;
+    }
+  }
+
+  if (config->style.type == kObjectTypeString) {
+    if (config->style.data.string.data[0] == NUL) {
+      fconfig->style = kWinStyleUnused;
+    } else if (striequal(config->style.data.string.data, "minimal")) {
+      fconfig->style = kWinStyleMinimal;
+    }  else {
+      api_set_error(err, kErrorTypeValidation, "Invalid value of 'style' key");
+    }
+  } else if (HAS_KEY(config->style)) {
+    api_set_error(err, kErrorTypeValidation, "'style' key must be String");
     return false;
   }
 
-  if (has_relative != has_row || has_row != has_col) {
-    api_set_error(err, kErrorTypeValidation,
-                  "'relative' requires 'row'/'col' or 'bufpos'");
-    return false;
+  if (HAS_KEY(config->noautocmd)) {
+    if (!new_win) {
+      api_set_error(err, kErrorTypeValidation, "Invalid key: 'noautocmd'");
+      return false;
+    }
+    fconfig->noautocmd = api_object_to_bool(config->noautocmd, "'noautocmd' key", false, err);
+    if (ERROR_SET(err)) {
+      return false;
+    }
   }
+
   return true;
 }
+
+bool api_dict_to_keydict(void *rv, field_hash hashy, Dictionary dict, Error *err)
+{
+  for (size_t i = 0; i < dict.size; i++) {
+    String k = dict.items[i].key;
+    Object *field = hashy(rv, k.data, k.size);
+    if (!field) {
+      api_set_error(err, kErrorTypeValidation, "Invalid key: '%.*s'", (int)k.size, k.data);
+      return false;
+    }
+
+    *field = dict.items[i].value;
+  }
+
+  return true;
+}
+
+void api_free_keydict(void *dict, KeySetLink *table)
+{
+  for (size_t i = 0; table[i].str; i++) {
+    api_free_object(*(Object *)((char *)dict + table[i].ptr_off));
+  }
+}
+
diff --git a/src/nvim/api/private/helpers.h b/src/nvim/api/private/helpers.h
index ecce6afa26..2cdd80bffe 100644
--- a/src/nvim/api/private/helpers.h
+++ b/src/nvim/api/private/helpers.h
@@ -59,6 +59,9 @@
 #define NIL ((Object)OBJECT_INIT)
 #define NULL_STRING ((String)STRING_INIT)
 
+// currently treat key=vim.NIL as if the key was missing
+#define HAS_KEY(o) ((o).type != kObjectTypeNil)
+
 #define PUT(dict, k, v) \
   kv_push(dict, ((KeyValuePair) { .key = cstr_to_string(k), .value = v }))
 
@@ -138,6 +141,9 @@ typedef struct {
   } while (0)
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "keysets.h.generated.h"
 # include "api/private/helpers.h.generated.h"
 #endif
+
+
 #endif  // NVIM_API_PRIVATE_HELPERS_H
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index e2d7c03307..f80d605d9a 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1424,7 +1424,7 @@ void nvim_chan_send(Integer chan, String data, Error *err)
 /// @param[out] err Error details, if any
 ///
 /// @return Window handle, or 0 on error
-Window nvim_open_win(Buffer buffer, Boolean enter, Dictionary config, Error *err)
+Window nvim_open_win(Buffer buffer, Boolean enter, Dict(float_config) *config, Error *err)
   FUNC_API_SINCE(6)
   FUNC_API_CHECK_TEXTLOCK
 {
@@ -1761,24 +1761,15 @@ Dictionary nvim_get_color_map(void)
 /// @param[out]  err  Error details, if any
 ///
 /// @return map of global |context|.
-Dictionary nvim_get_context(Dictionary opts, Error *err)
+Dictionary nvim_get_context(Dict(context) *opts, Error *err)
   FUNC_API_SINCE(6)
 {
   Array types = ARRAY_DICT_INIT;
-  for (size_t i = 0; i < opts.size; i++) {
-    String k = opts.items[i].key;
-    Object v = opts.items[i].value;
-    if (strequal("types", k.data)) {
-      if (v.type != kObjectTypeArray) {
-        api_set_error(err, kErrorTypeValidation, "invalid value for key: %s",
-                      k.data);
-        return (Dictionary)ARRAY_DICT_INIT;
-      }
-      types = v.data.array;
-    } else {
-      api_set_error(err, kErrorTypeValidation, "unexpected key: %s", k.data);
-      return (Dictionary)ARRAY_DICT_INIT;
-    }
+  if (opts->types.type == kObjectTypeArray) {
+    types = opts->types.data.array;
+  } else if (opts->types.type != kObjectTypeNil) {
+    api_set_error(err, kErrorTypeValidation, "invalid value for key: types");
+    return (Dictionary)ARRAY_DICT_INIT;
   }
 
   int int_types = types.size > 0 ? 0 : kCtxAll;
@@ -1888,7 +1879,7 @@ ArrayOf(Dictionary) nvim_get_keymap(String mode)
 ///               as keys excluding |<buffer>| but including |noremap|.
 ///               Values are Booleans. Unknown key is an error.
 /// @param[out]   err   Error details, if any.
-void nvim_set_keymap(String mode, String lhs, String rhs, Dictionary opts, Error *err)
+void nvim_set_keymap(String mode, String lhs, String rhs, Dict(keymap) *opts, Error *err)
   FUNC_API_SINCE(6)
 {
   modify_keymap(-1, false, mode, lhs, rhs, opts, err);
@@ -1914,7 +1905,7 @@ void nvim_del_keymap(String mode, String lhs, Error *err)
 /// @param[out]  err   Error details, if any.
 ///
 /// @returns Map of maps describing commands.
-Dictionary nvim_get_commands(Dictionary opts, Error *err)
+Dictionary nvim_get_commands(Dict(get_commands) *opts, Error *err)
   FUNC_API_SINCE(4)
 {
   return nvim_buf_get_commands(-1, opts, err);
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 99ba297111..95eae1af2d 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -385,7 +385,7 @@ Boolean nvim_win_is_valid(Window window)
 /// @param      config  Map defining the window configuration,
 ///                     see |nvim_open_win()|
 /// @param[out] err     Error details, if any
-void nvim_win_set_config(Window window, Dictionary config, Error *err)
+void nvim_win_set_config(Window window, Dict(float_config) *config, Error *err)
   FUNC_API_SINCE(6)
 {
   win_T *win = find_window_by_handle(window, err);
diff --git a/src/nvim/generators/c_grammar.lua b/src/nvim/generators/c_grammar.lua
index c9ab0cf709..a5f76e1c6a 100644
--- a/src/nvim/generators/c_grammar.lua
+++ b/src/nvim/generators/c_grammar.lua
@@ -17,7 +17,7 @@ local fill = ws ^ 0
 local c_comment = P('//') * (not_nl ^ 0)
 local c_preproc = P('#') * (not_nl ^ 0)
 local typed_container =
-  (P('ArrayOf(') + P('DictionaryOf(')) * ((any - P(')')) ^ 1) * P(')')
+  (P('ArrayOf(') + P('DictionaryOf(') + P('Dict(')) * ((any - P(')')) ^ 1) * P(')')
 local c_id = (
   typed_container +
   (letter * (alpha ^ 0))
diff --git a/src/nvim/generators/gen_api_dispatch.lua b/src/nvim/generators/gen_api_dispatch.lua
index 99d80cdebc..6ed2e5dab8 100644
--- a/src/nvim/generators/gen_api_dispatch.lua
+++ b/src/nvim/generators/gen_api_dispatch.lua
@@ -152,6 +152,8 @@ for _,f in ipairs(functions) do
     for i,param in ipairs(f.parameters) do
       if param[1] == "DictionaryOf(LuaRef)" then
         param = {"Dictionary", param[2]}
+      elseif startswith(param[1], "Dict(") then
+        param = {"Dictionary", param[2]}
       end
       f_exported.parameters[i] = param
     end
@@ -173,7 +175,10 @@ local output = io.open(dispatch_outputf, 'wb')
 
 local function real_type(type)
   local rv = type
-  if c_grammar.typed_container:match(rv) then
+  local rmatch = string.match(type, "Dict%(([_%w]+)%)")
+  if rmatch then
+    return "KeyDict_"..rmatch
+  elseif c_grammar.typed_container:match(rv) then
     if rv:match('Array') then
       rv = 'Array'
     else
@@ -209,8 +214,9 @@ for i = 1, #functions do
     -- Declare/initialize variables that will hold converted arguments
     for j = 1, #fn.parameters do
       local param = fn.parameters[j]
+      local rt = real_type(param[1])
       local converted = 'arg_'..j
-      output:write('\n  '..param[1]..' '..converted..';')
+      output:write('\n  '..rt..' '..converted..';')
     end
     output:write('\n')
     output:write('\n  if (args.size != '..#fn.parameters..') {')
@@ -225,7 +231,24 @@ for i = 1, #functions do
       param = fn.parameters[j]
       converted = 'arg_'..j
       local rt = real_type(param[1])
-      if rt ~= 'Object' then
+      if rt == 'Object' then
+        output:write('\n  '..converted..' = args.items['..(j - 1)..'];\n')
+      elseif rt:match('^KeyDict_') then
+        converted = '&' .. converted
+        output:write('\n  if (args.items['..(j - 1)..'].type == kObjectTypeDictionary) {') --luacheck: ignore 631
+        output:write('\n    memset('..converted..', 0, sizeof(*'..converted..'));') -- TODO: neeeee
+        output:write('\n    if (!api_dict_to_keydict('..converted..', '..rt..'_get_field, args.items['..(j - 1)..'].data.dictionary, error)) {')
+        output:write('\n      goto cleanup;')
+        output:write('\n    }')
+          output:write('\n  } else if (args.items['..(j - 1)..'].type == kObjectTypeArray && args.items['..(j - 1)..'].data.array.size == 0) {') --luacheck: ignore 631
+        output:write('\n    memset('..converted..', 0, sizeof(*'..converted..'));')
+
+        output:write('\n  } else {')
+        output:write('\n    api_set_error(error, kErrorTypeException, \
+          "Wrong type for argument '..j..' when calling '..fn.name..', expecting '..param[1]..'");')
+        output:write('\n    goto cleanup;')
+        output:write('\n  }\n')
+      else
         if rt:match('^Buffer$') or rt:match('^Window$') or rt:match('^Tabpage$') then
           -- Buffer, Window, and Tabpage have a specific type, but are stored in integer
           output:write('\n  if (args.items['..
@@ -257,10 +280,7 @@ for i = 1, #functions do
           "Wrong type for argument '..j..' when calling '..fn.name..', expecting '..param[1]..'");')
         output:write('\n    goto cleanup;')
         output:write('\n  }\n')
-      else
-        output:write('\n  '..converted..' = args.items['..(j - 1)..'];\n')
       end
-
       args[#args + 1] = converted
     end
 
@@ -423,13 +443,24 @@ local function process_function(fn)
     if param[1] == "DictionaryOf(LuaRef)" then
       extra = "true, "
     end
+    local errshift = 0
+    if string.match(param_type, '^KeyDict_') then
+      write_shifted_output(output, string.format([[
+      %s %s = { 0 }; nlua_pop_keydict(lstate, &%s, %s_get_field, %s&err);]], param_type, cparam, cparam, param_type, extra))
+      cparam = '&'..cparam
+      errshift = 1 -- free incomplete dict on error
+    else
+      write_shifted_output(output, string.format([[
+      const %s %s = nlua_pop_%s(lstate, %s&err);]], param[1], cparam, param_type, extra))
+    end
+
     write_shifted_output(output, string.format([[
-    const %s %s = nlua_pop_%s(lstate, %s&err);
 
     if (ERROR_SET(&err)) {
       goto exit_%u;
     }
-    ]], param[1], cparam, param_type, extra, #fn.parameters - j))
+
+    ]], #fn.parameters - j + errshift))
     free_code[#free_code + 1] = ('api_free_%s(%s);'):format(
       lc_param_type, cparam)
     cparams = cparam .. ', ' .. cparams
@@ -446,7 +477,7 @@ local function process_function(fn)
   for i = 1, #free_code do
     local rev_i = #free_code - i + 1
     local code = free_code[rev_i]
-    if i == 1 then
+    if i == 1 and not string.match(real_type(fn.parameters[1][1]), '^KeyDict_') then
       free_at_exit_code = free_at_exit_code .. ('\n    %s'):format(code)
     else
       free_at_exit_code = free_at_exit_code .. ('\n  exit_%u:\n    %s'):format(
diff --git a/src/nvim/generators/gen_declarations.lua b/src/nvim/generators/gen_declarations.lua
index 0782c8115d..97491679a4 100755
--- a/src/nvim/generators/gen_declarations.lua
+++ b/src/nvim/generators/gen_declarations.lua
@@ -60,7 +60,7 @@ local right_word = concat(
 )
 local word = branch(
   concat(
-    branch(lit('ArrayOf('), lit('DictionaryOf(')), -- typed container macro
+    branch(lit('ArrayOf('), lit('DictionaryOf('), lit('Dict(')), -- typed container macro
     one_or_more(any_character - lit(')')),
     lit(')')
   ),
diff --git a/src/nvim/generators/gen_keysets.lua b/src/nvim/generators/gen_keysets.lua
new file mode 100644
index 0000000000..63ef202fe1
--- /dev/null
+++ b/src/nvim/generators/gen_keysets.lua
@@ -0,0 +1,67 @@
+
+local nvimsrcdir = arg[1]
+local shared_file = arg[2]
+local funcs_file = arg[3]
+local defs_file = arg[4]
+
+_G.vim = loadfile(shared_file)()
+
+if nvimsrcdir == '--help' then
+  print([[
+Usage:
+  lua gen_keyset.lua TODOFIXUPDATETHIS
+
+Will generate build/src/nvim/auto/keyset.generated.h with definition of functions
+static const array.
+]])
+  os.exit(0)
+end
+
+
+package.path = nvimsrcdir .. '/?.lua;' .. package.path
+local hashy = require'generators.hashy'
+
+local funcspipe = io.open(funcs_file, 'wb')
+local defspipe = io.open(defs_file, 'wb')
+
+local keysets = require'api.keysets'
+
+for name, keys in pairs(keysets) do
+  local neworder, hashfun = hashy.hashy_hash(name, keys, function (idx)
+    return name.."_table["..idx.."].str"
+  end)
+
+  defspipe:write("typedef struct {\n")
+  for _, key in ipairs(neworder) do
+    defspipe:write("  Object "..key..";\n")
+  end
+  defspipe:write("} KeyDict_"..name..";\n\n")
+
+  defspipe:write("extern KeySetLink "..name.."_table[];\n")
+
+  funcspipe:write("KeySetLink "..name.."_table[] = {\n")
+  for _, key in ipairs(neworder) do
+    funcspipe:write('  {"'..key..'", offsetof(KeyDict_'..name..", "..key..")},\n")
+  end
+    funcspipe:write('  {NULL, 0},\n')
+  funcspipe:write("};\n\n")
+
+  funcspipe:write(hashfun)
+
+  funcspipe:write([[
+Object *KeyDict_]]..name..[[_get_field(void *retval, const char *str, size_t len)
+{
+  int hash = ]]..name..[[_hash(str, len);
+  if (hash == -1) {
+    return NULL;
+  }
+
+  return (Object *)((char *)retval + ]]..name..[[_table[hash].ptr_off);
+}
+
+]])
+  defspipe:write("#define api_free_keydict_"..name.."(x) api_free_keydict(x, "..name.."_table)\n")
+end
+
+funcspipe:close()
+defspipe:close()
diff --git a/src/nvim/generators/hashy.lua b/src/nvim/generators/hashy.lua
new file mode 100644
index 0000000000..fac24c810a
--- /dev/null
+++ b/src/nvim/generators/hashy.lua
@@ -0,0 +1,122 @@
+-- HASHY McHASHFACE
+
+local M = {}
+_G.d = M
+
+
+local function setdefault(table, key)
+  local val = table[key]
+  if val == nil then
+    val = {}
+    table[key] = val
+  end
+  return val
+end
+
+function M.build_pos_hash(strings)
+  local len_buckets = {}
+  local maxlen = 0
+  for _,s in ipairs(strings) do
+    table.insert(setdefault(len_buckets, #s),s)
+    if #s > maxlen then maxlen = #s end
+  end
+
+  local len_pos_buckets = {}
+  local worst_buck_size = 0
+
+  for len = 1,maxlen do
+    local strs = len_buckets[len]
+    if strs then
+      -- the best position so far generates `best_bucket`
+      -- with `minsize` worst case collisions
+      local bestpos, minsize, best_bucket = nil, #strs*2, nil
+      for pos = 1,len do
+        local try_bucket = {}
+        for _,str in ipairs(strs) do
+          local poschar = string.sub(str, pos, pos)
+          table.insert(setdefault(try_bucket, poschar), str)
+        end
+        local maxsize = 1
+        for _,pos_strs in pairs(try_bucket) do
+          maxsize = math.max(maxsize, #pos_strs)
+        end
+        if maxsize < minsize then
+          bestpos = pos
+          minsize = maxsize
+          best_bucket = try_bucket
+        end
+      end
+      len_pos_buckets[len] = {bestpos, best_bucket}
+      worst_buck_size = math.max(worst_buck_size, minsize)
+    end
+  end
+  return len_pos_buckets, maxlen, worst_buck_size
+end
+
+function M.switcher(put, tab, maxlen, worst_buck_size)
+  local neworder = {}
+  put "  switch (len) {\n"
+  local bucky = worst_buck_size > 1
+  for len = 1,maxlen do
+    local vals = tab[len]
+    if vals then
+      put("    case "..len..": ")
+      local pos, posbuck = unpack(vals)
+      local keys = vim.tbl_keys(posbuck)
+      if #keys > 1 then
+        table.sort(keys)
+        put("switch (str["..(pos-1).."]) {\n")
+        for _,c in ipairs(keys) do
+          local buck = posbuck[c]
+          local startidx = #neworder
+          vim.list_extend(neworder, buck)
+          local endidx = #neworder
+          put("      case '"..c.."': ")
+          put("low = "..startidx.."; ")
+          if bucky then put("high = "..endidx.."; ") end
+          put "break;\n"
+        end
+        put "      default: break;\n"
+        put "    }\n  "
+      else
+          local startidx = #neworder
+          table.insert(neworder, posbuck[keys[1]][1])
+          local endidx = #neworder
+          put("low = "..startidx.."; ")
+          if bucky then put("high = "..endidx.."; ") end
+      end
+      put "  break;\n"
+    end
+  end
+  put "    default: break;\n"
+  put "  }\n"
+  return neworder
+end
+
+function M.hashy_hash(name, strings, access)
+  local stats = {}
+  local put = function(str) table.insert(stats, str) end
+  local len_pos_buckets, maxlen, worst_buck_size = M.build_pos_hash(strings)
+  put("int "..name.."_hash(const char *str, size_t len)\n{\n")
+  if worst_buck_size > 1 then
+    put("  int low = 0, high = 0;\n")
+  else
+    put("  int low = -1;\n")
+  end
+  local neworder = M.switcher(put, len_pos_buckets, maxlen, worst_buck_size)
+  if worst_buck_size > 1 then
+    error [[ not implemented yet ]] -- TODO(bfredl)
+  else
+    put [[
+  if (low < 0) {
+    return -1;
+  }
+  ]]
+    put("if(memcmp(str, "..access("low")..", len)) {\n    return -1;\n  }\n")
+    put "  return low;\n"
+    put "}\n\n"
+  end
+  return neworder, table.concat(stats)
+end
+
+return M
diff --git a/src/nvim/getchar.h b/src/nvim/getchar.h
index f0b52079aa..83fa00977f 100644
--- a/src/nvim/getchar.h
+++ b/src/nvim/getchar.h
@@ -56,6 +56,8 @@ struct map_arguments {
   size_t orig_rhs_len;
 };
 typedef struct map_arguments MapArguments;
+#define MAP_ARGUMENTS_INIT { false, false, false, false, false, false, false, \
+                             { 0 }, 0, NULL, 0, false, NULL, 0 }
 
 #define KEYLEN_PART_KEY -1  // keylen value for incomplete key-code
 #define KEYLEN_PART_MAP -2  // keylen value for incomplete mapping
diff --git a/src/nvim/lua/converter.c b/src/nvim/lua/converter.c
index fac5bab664..fd4cfc4c31 100644
--- a/src/nvim/lua/converter.c
+++ b/src/nvim/lua/converter.c
@@ -1299,3 +1299,25 @@ void nlua_init_types(lua_State *const lstate)
 
   lua_rawset(lstate, -3);
 }
+
+
+void nlua_pop_keydict(lua_State *L, void *retval, field_hash hashy, Error *err)
+{
+  lua_pushnil(L);  // [dict, nil]
+  while (lua_next(L, -2)) {
+    // [dict, key, value]
+    size_t len;
+    const char *s = lua_tolstring(L, -2, &len);
+    Object *field = hashy(retval, s, len);
+    if (!field) {
+      api_set_error(err, kErrorTypeValidation, "invalid key: %.*s", (int)len, s);
+      lua_pop(L, 3);  // []
+      return;
+    }
+
+    *field = nlua_pop_Object(L, true, err);
+  }
+  // [dict]
+  lua_pop(L, 1);
+  // []
+}
diff --git a/src/nvim/msgpack_rpc/helpers.c b/src/nvim/msgpack_rpc/helpers.c
index b1b9c77953..549016e751 100644
--- a/src/nvim/msgpack_rpc/helpers.c
+++ b/src/nvim/msgpack_rpc/helpers.c
@@ -15,6 +15,7 @@
 #include "nvim/vim.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "keysets.generated.h"
 # include "msgpack_rpc/helpers.c.generated.h"
 #endif
 
diff --git a/test/config/paths.lua.in b/test/config/paths.lua.in
index 7fe5d8ad80..e3979981ba 100644
--- a/test/config/paths.lua.in
+++ b/test/config/paths.lua.in
@@ -19,5 +19,6 @@ if module.test_luajit_prg == '' then
   end
 end
 table.insert(module.include_paths, "${CMAKE_BINARY_DIR}/include")
+table.insert(module.include_paths, "${CMAKE_BINARY_DIR}/src/nvim/auto")
 
 return module
diff --git a/test/functional/api/command_spec.lua b/test/functional/api/command_spec.lua
index 37331d11c7..6f929ad1ca 100644
--- a/test/functional/api/command_spec.lua
+++ b/test/functional/api/command_spec.lua
@@ -21,7 +21,7 @@ describe('nvim_get_commands', function()
   it('validates input', function()
     eq('builtin=true not implemented', pcall_err(meths.get_commands,
       {builtin=true}))
-    eq('unexpected key: foo', pcall_err(meths.get_commands,
+    eq("Invalid key: 'foo'", pcall_err(meths.get_commands,
       {foo='blah'}))
   end)
 
diff --git a/test/functional/api/keymap_spec.lua b/test/functional/api/keymap_spec.lua
index 4194945645..dd8eef7ca0 100644
--- a/test/functional/api/keymap_spec.lua
+++ b/test/functional/api/keymap_spec.lua
@@ -436,16 +436,16 @@ describe('nvim_set_keymap, nvim_del_keymap', function()
   end)
 
   it('error on invalid optnames', function()
-    eq('Invalid key: silentt',
+    eq("Invalid key: 'silentt'",
       pcall_err(meths.set_keymap, 'n', 'lhs', 'rhs', {silentt = true}))
-    eq('Invalid key: sidd',
+    eq("Invalid key: 'sidd'",
       pcall_err(meths.set_keymap, 'n', 'lhs', 'rhs', {sidd = false}))
-    eq('Invalid key: nowaiT',
+    eq("Invalid key: 'nowaiT'",
       pcall_err(meths.set_keymap, 'n', 'lhs', 'rhs', {nowaiT = false}))
   end)
 
   it('error on <buffer> option key', function()
-    eq('Invalid key: buffer',
+    eq("Invalid key: 'buffer'",
       pcall_err(meths.set_keymap, 'n', 'lhs', 'rhs', {buffer = true}))
   end)
 
@@ -454,8 +454,8 @@ describe('nvim_set_keymap, nvim_del_keymap', function()
     -- note: need '%' to escape hyphens, which have special meaning in lua
     it('throws an error when given non-boolean value for '..opt, function()
       local opts = {}
-      opts[opt] = 2
-      eq('Gave non-boolean value for an opt: '..opt,
+      opts[opt] = 'fooo'
+      eq(opt..' is not a boolean',
         pcall_err(meths.set_keymap, 'n', 'lhs', 'rhs', opts))
     end)
   end
diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index df602ed48c..6bcf8dd91f 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -1119,7 +1119,7 @@ describe('API', function()
 
   describe('nvim_get_context', function()
     it('validates args', function()
-      eq('unexpected key: blah',
+      eq("Invalid key: 'blah'",
         pcall_err(nvim, 'get_context', {blah={}}))
       eq('invalid value for key: types',
         pcall_err(nvim, 'get_context', {types=42}))
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index 79f308cf26..e57c63bb0f 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -1529,7 +1529,7 @@ describe('float window', function()
 
     it('API has proper error messages', function()
       local buf = meths.create_buf(false,false)
-      eq("Invalid key 'bork'",
+      eq("Invalid key: 'bork'",
          pcall_err(meths.open_win,buf, false, {width=20,height=2,bork=true}))
       eq("'win' key is only valid with relative='win'",
          pcall_err(meths.open_win,buf, false, {width=20,height=2,relative='editor',row=0,col=0,win=0}))
@@ -1542,13 +1542,15 @@ describe('float window', function()
       eq("'relative' requires 'row'/'col' or 'bufpos'",
          pcall_err(meths.open_win,buf, false, {width=20,height=2,relative='editor'}))
       eq("'width' key must be a positive Integer",
-         pcall_err(meths.open_win,buf, false, {width=-1,height=2,relative='editor'}))
+         pcall_err(meths.open_win,buf, false, {width=-1,height=2,relative='editor', row=0, col=0}))
       eq("'height' key must be a positive Integer",
-         pcall_err(meths.open_win,buf, false, {width=20,height=-1,relative='editor'}))
+         pcall_err(meths.open_win,buf, false, {width=20,height=-1,relative='editor', row=0, col=0}))
       eq("'height' key must be a positive Integer",
-         pcall_err(meths.open_win,buf, false, {width=20,height=0,relative='editor'}))
-      eq("Must specify 'width' and 'height'",
-         pcall_err(meths.open_win,buf, false, {relative='editor'}))
+         pcall_err(meths.open_win,buf, false, {width=20,height=0,relative='editor', row=0, col=0}))
+      eq("Must specify 'width'",
+         pcall_err(meths.open_win,buf, false, {relative='editor', row=0, col=0}))
+      eq("Must specify 'height'",
+         pcall_err(meths.open_win,buf, false, {relative='editor', row=0, col=0, width=2}))
     end)
 
     it('can be placed relative window or cursor', function()