Sort output of let or set

Question

How to sort the output of let or get? E.g., I want to sort all global variables containing "python":

:filter python let g:

Answer 1

1. You can capture output with execute() function and then pump it through sort(). The whole command could be then:

   command! -bang -nargs=1 -complete=command Sorted
       \ echo join(sort(split(execute(<q-mods> . ' ' . <q-args>), "\n"),
           \ {s1, s2 -> <bang>(s1 ># s2) - <bang>(s1 <# s2)}), "\n")
   

Now you can do :Sorted filter python let g:

2. If it makes sense to create a more flexible solution, you can capture command output into a temporary buffer instead. And once it's in a buffer, :sort-ing (or any other kind of processing) becomes easy.

   nnoremap <silent><leader>x :put =trim(execute(input(':', '', 'command')))<CR>
   

Now press <leader>x and enter your command. When the output gets into a buffer you can :sort it as usual.

Answer 2

Here is a different approach. :filter let will only look for matching variable names, so you can re-implement it using filter() function and sort the resulting dict and output all matches afterwards. This is using the new method functionality of Vim 8.1 and a lambda expression.

for val in sort(keys((copy(g:)->filter({k -> k =~# 'python'}))))|echo printf("%s: %s", val, g:[val])|endfor

Note: we are copy()ing the global dict first, because filter() filters the given dictionary in place, which we do not want here.