compose.vim

function! g:Compose(...)
  let l:args = a:000
  return {...->eval(execute("let ret = a:000|let i = (len(".string(l:args).")-1)"
        \ ."|while i>-1|let ret = [call(".string(l:args)."[i],ret)]"
        \ ."|let i -= 1|endwhile|echon string(ret[0])"))}
endfunction
echom Compose('toupper','join','uniq','split','printf')('%s','aa bb aa aa b b b b')