fold doc comments

ftplugin/idris.vim

@@ -1,14 +1,30 @@
+if exists("b:did_ftplugin")
+  finish
+endif
+
 setlocal shiftwidth=2
 setlocal tabstop=2
 setlocal expandtab
 
-let idris_response=0
+let idris_response = 0
+let b:did_ftplugin = 1
 
-if exists("b:did_ftplugin")
-  finish
-endif
+function! IdrisDocFold(lineNum)
+  let line = getline(a:lineNum)
 
-let b:did_ftplugin = 1
+  if line =~ "^\s*|||"
+    return "1"
+  endif
+
+  return "0"
+endfunction
+
+function! IdrisFold(lineNum)
+  return IdrisDocFold(a:lineNum)
+endfunction
+
+setlocal foldmethod=expr
+setlocal foldexpr=IdrisFold(v:lnum)
 
 function! IdrisResponseWin()
   if (!bufexists("idris-response"))