[really] poor proof-of-concept [spac]emacs which-key port to vim | demo https://upload.teknik.io/8olPd.webm

discover.vim

" If you want to test this, save it somewhere, open in vim, `:so %`.
" Slowly type <leader>g andand g-commands should happen in the other buffer.
" In the demo webm above, I just slowly typed `<leader>gJ`
" I only added descriptions for a few commands but others should work
" Needs massive re-working to actually be maintainable

" WHY:
" Vim is an amazing tool, but one of it's few weaknesses is discoverability.
" While it's great to have a tool that you can continually learn new things about,
" learning those things would ideally happen sooner than later. Spacemacs ships with "which-key"
" that will show you hints about what key binds would make sense after other key binds. The user
" types `g` and and spacemacs shows a list of valid `g` commands. The idea here is,
" pushing <leader> shows you a list of commands valid in normal mode, pushing another key
" should show valid commands for that key..
" There are things like `:Unite mapping` that show lists of maps, but that only lists things
" that the user has added, it doesn't list default binds, and doesn't give any description about
" what the map should do..

function! s:Discover() abort
  let string = ''
  " TODO: symbols,usermaps
  let keys = {
  \ 'q': 'macro',
  \ 'Q': 'start Ex mode',
  \ 'w': 'move forward a word',
  \ 'W': 'move forward a WORD',
  \ 'e': 'move to end of word',
  \ 'E': 'move to end of WORD',
  \ 'r': 'replace char under cursor',
  \ 'R': 'start replace mode',
  \ 't': 'move cursor forward til char',
  \ 'T': 'move cursor backward til char',
  \ 'y': 'yank [motion]',
  \ 'Y': 'yank line',
  \ 'u': 'undo',
  \ 'U': 'undo changes to line',
  \ 'i': 'insert mode at cursor',
  \ 'I': 'insert mode at beginning of line',
  \ 'o': 'insert mode below cursor',
  \ 'O': 'insert mode above cursor',
  \ 'p': 'paste at cursor',
  \ 'P': 'paste before cursor',
  \ 'a': 'insert mode after cursor',
  \ 'A': 'insert mode at end of line',
  \ 's': 'substitute char under cursor',
  \ 'S': 'substitute current line',
  \ 'd': 'delete [motion]',
  \ 'D': 'delete to end of line',
  \ 'f': 'move cursor forward to char',
  \ 'F': 'move cursor backward to char',
  \ 'g': 'general',
  \ 'G': 'move cursor to end of file',
  \ 'h': 'move left one char',
  \ 'H': 'move cursor to top of screen',
  \ 'j': 'move down one line',
  \ 'J': 'join line below to current',
  \ 'k': 'move up one line',
  \ 'K': 'show man page for word under cursor',
  \ 'l': 'move right one char',
  \ 'L': 'move cursor to bottom of screen',
  \ 'z': 'folds',
  \ 'Z': 'quit',
  \ 'x': 'delete char under cursor',
  \ 'X': 'delete char before cursor',
  \ 'c': 'change [motion]',
  \ 'C': 'change to end of line',
  \ 'v': 'visually select chars',
  \ 'V': 'visually select lines',
  \ 'b': 'move back a word',
  \ 'B': 'move back a WORD',
  \ 'n': 'move cursor to next match',
  \ 'N': 'move cursor to previous match',
  \ 'm': 'mark',
  \ 'M': 'move cursor to middle of screen'
  \ }
  split
  enew
  call s:PrintMapList(keys)
  nnoremap <silent><buffer> <Esc> <C-w>q
  setlocal bt=nofile bh=wipe nobl noswf nonu nornu nolist
  silent! redraw!
  let char = nr2char(getchar())
  if exists('*s:Discover_' . char)
    execute 'call s:Discover_' . char . '()'
  else
    wincmd q
    execute 'normal ' . char
  endif
  silent! redraw!
endfunction
command! -nargs=* Discover call s:Discover()
nnoremap <Leader> :Discover<CR>

function! s:Discover_g() abort
  " FIXME: this is tiresome... scrape help files?
  let g_keys = {
  \ 'ge': 'go backwards to end of previous word',
  \ 'gE': 'go backwards to end of previous WORD',
  \ 'gJ': 'join lines without inserting space'
  \ }
  call s:PrintMapList(g_keys)
  let char = nr2char(getchar())
  wincmd q
  execute 'normal g' . char
  silent! redraw!
endfunction

function! s:PrintMapList(list) abort
  %d
  for i in items(a:list)
    $put =join(i, ' - ')
  endfor
  if empty(getline('1'))
    1d
  endif
  wincmd H
  vert resize 60
  silent! redraw!
endfunction