gistfile1.vim

nnoremap <buffer> <SID>[ghcmod] <Nop>
nmap <buffer> <Leader>h <SID>[ghcmod]
nnoremap <buffer> <silent> <SID>[ghcmod]y :<C-u>call <SID>paste_type_signature()<CR>

function! s:paste_type_signature()
  try
    let signature = expand('<cword>').' :: '.ghcmod#type()[1]
  catch
    return
  endtry
  call ghcmod#type_clear()
  silent .-1 put =signature
endfunction