Expl3 regex and missing semicolon?

Question

Try to make an answer to this question How to go about creating custom parser in Latex, I have the following problem. The result of the macro seem no conform to what I expect :

(1:1)--(-1:2)--(2,2)

or there is a problem related to expansion ...

\documentclass{article}
\usepackage{tikz,expl3,xparse}

\ExplSyntaxOn

\NewDocumentCommand{\makelinesegment}{ m } {
    \tl_set:Nn \l_bob_func_tl { #1 }
    \regex_replace_all:nnN { ([0-9])- } { \1)--( } \l_bob_func_tl
    \regex_replace_all:nnN { : } { , } \l_bob_func_tl
    (\l_bob_func_tl)
}

\ExplSyntaxOff

\begin{document}

\makelinesegment{1:1--1:2-2:2}

% If uncommented 
% Package tikz Error: Giving up on this path. Did you forget a semicolon?.
%\tikz\draw \makelinesegment{1:1--1:2-2:2} ;

\end{document}

Answer 1

If you are only going to use this inside TikZ:

\documentclass{article}

\usepackage{tikz,xparse}

\ExplSyntaxOn

\tl_new:N \l_bob_func_tl

\NewDocumentCommand \makelinesegment { m }
 {
  \pgfextra
  \tl_set:Nn \l_bob_func_tl { #1 }
  \regex_replace_all:nnN { ([0-9])- } { \1)--( } \l_bob_func_tl
  \regex_replace_all:nnN { : } { , } \l_bob_func_tl
  \exp_last_unbraced:NNV % this is not necessary, but I find it cleaner, correct me if I'm wrong
  \endpgfextra
  (\l_bob_func_tl)
 }

\ExplSyntaxOff

\begin{document}

% \makelinesegment{1:1--1:2-2:2} % do not use outside `\tikz` or `{tikzpicture}`

\tikz\draw\makelinesegment{1:1--1:2-2:2};

\end{document}

If you need outside too we need to add a boolean somewhere, say it if you need it.