a.rb

function! Viadict(word, thesaurus)
  if !exists('g:viadict_window')
    let g:viadict_window = bufnr('viadict_window', 1)
  endif

  if bufnr('%') != g:viadict_window 
    execute "below sb " . g:viadict_window
  endif

  setlocal buftype=nofile
  setlocal bufhidden=hide
  setlocal noswapfile
  resize 10
  au! * <buffer>
  au BufLeave <buffer> hide 
  setlocal noro
  execute "%d"
  if a:thesaurus
    execute "0r ! viadict -t " . a:word 
  else 
    execute "0r ! viadict " . a:word 
  endif
  setlocal readonly
  normal! gg
endfunction