function to put function parameters one-per-line.

gistfile1.vim

" NOTES: 
" ^M must be replaced with <ctrl-v><ctrl-m>
" ^[ must be replace with <ctl-v><esc>

function! BreakParameters()
    " move the start of the line and set a mark 'a'
    normal ^ma
    " get break the parameters onto their own line
    normal f(a^M^[
    " replace the commas with linebreaks
    :s/\v,[\s\n]?/,^M/g
    " reformat the paragraph
    normal V`'=
    " clean up by deleting the mark
    :delmarks a
    " turn off the highlighting
    :nohl
endfunction