Parse input into commands in expl3

Question

Cheers to @egreg again for these nice expl3 tricks that finally led me to this \apply macro I use all.the.time:

\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
% use: \apply[parse][separator]{function}{list}
\NewDocumentCommand{\apply}{ O{##1}  O{} m +m}{%
    \Apply:nnnf { #1 } { #2 } { #3 } { #4 }%
}
% The list built and processed from the input items.
\seq_new:N \l__Apply_input_seq
% The list finally reinjected in the input stream with separators.
\seq_new:N \l__Apply_output_seq
% Main function.
\cs_new_protected:Nn \Apply:nnnn
 {%
  % Build up input list from comma-separated items.
  \seq_set_from_clist:Nn \l__Apply_input_seq { #4 }%
  % Define the function to map along the parsed sequence.
  \cs_set:Npn __Apply_process_multi_args:w%
      #1 \q_stop            % The 'arguments'
      { \exp_not:n { #3 } } % The 'body'
  % Wrap the mapped function into a function that only takes 1 argument.
  \cs_set:Nn __Apply_process_single_arg:n%
    { __Apply_process_multi_args:w ##1 \q_stop }%
  % Map the function along the sequence.
  \seq_set_map:NNn \l__Apply_output_seq \l__Apply_input_seq%
  {%
      % Expansion fiddling?
      __Apply_process_single_arg:f { \exp_not:n { ##1 } }%
  }%
  % Reinject into the input stream with the requested separator.
  \seq_use:Nn \l__Apply_output_seq { #2 }%
 }
% Extend signature so it correctly expands items?
\cs_generate_variant:Nn __Apply_process_single_arg:n { f }%
% Extend signature so it correctly expands the input list?
\cs_generate_variant:Nn \Apply:nnnn { nnnf }%
\ExplSyntaxOff
\begin{document}
\apply[#1:#2 -> #3][, ]{%
    #1 and #2 yield #3%
}{
    first:last -> mid,
    5:8 -> 13,
    good:bad -> well,
}
\end{document}

With this I get:

To refine my use of \apply, I would love the [parse] argument to provide named slots, that expl3 would convert to expandable csnames within the {function} body. I a nutshell, the above call would be replaced with

\apply[\some:\other -> \result][, ]{%
    \some{} and \other{} yield \result
}{
    first:last -> mid,
    5:8 -> 13,
    good:bad -> well,
}

And why not a mix of both worlds?

\apply[#1:\other -> #2][, ]{%
    #1 and \other{} yield #2%
}{
    first:last -> mid,
    5:8 -> 13,
    good:bad -> well,
}

Is this achievable with expl3? What could I get started with?