Update

ftplugin/scala/tagbar.vim

@@ -0,0 +1,47 @@
+"
+" Support for Tagbar -- https://github.com/majutsushi/tagbar
+"
+" Hat tip to Leonard Ehrenfried for the built-in ctags deffile:
+"    https://leonard.io/blog/2013/04/editing-scala-with-vim/
+"
+if !exists(':Tagbar')
+  finish
+endif
+
+let g:tagbar_type_scala = {
+    \ 'ctagstype' : 'scala',
+    \ 'kinds'     : [
+      \ 'p:packages:1',
+      \ 'V:values',
+      \ 'v:variables',
+      \ 'T:types',
+      \ 't:traits',
+      \ 'o:objects',
+      \ 'a:aclasses',
+      \ 'c:classes',
+      \ 'r:cclasses',
+      \ 'm:methods'
+    \ ],
+    \ 'sro'        : '.',
+    \ 'kind2scope' : {
+        \ 'T' : 'type',
+        \ 't' : 'trait',
+        \ 'o' : 'object',
+        \ 'a' : 'abstract class',
+        \ 'c' : 'class',
+        \ 'r' : 'case class'
+    \ },
+    \ 'scope2kind' : {
+      \ 'type' : 'T',
+      \ 'trait' : 't',
+      \ 'object' : 'o',
+      \ 'abstract class' : 'a',
+      \ 'class' : 'c',
+      \ 'case class' : 'r'
+    \ }
+\ }
+
+" In case you've updated/customized your ~/.ctags and prefer to use it.
+if get(g:, 'scala_use_builtin_tagbar_defs', 1)
+  let g:tagbar_type_scala.deffile = expand('<sfile>:p:h:h:h') . '/ctags/scala.ctags'
+endif