Problem converting code from luacode to \directlua

Perhaps a question for David ?

I thought it would be interesting to be able to use unicode Greek characters directly to name nodes (points) with tkz-elements. I have no problem with the naming and all the macros seem to work correctly, but the problem arises with the tkzLabelPoint macro. As a first step, I've decided to create a new macro dedicated to Greek characters: \tkzLabelGPoint and I have a solution to automate this, but with the help of the luacode environment. I'd like to be able to use the directlua macro ... and I can't.

I hesitated about which question to ask. It's possible I've been wrong all along. Is it easier not to use lua?

\documentclass{article}
\usepackage[mini]{tkz-euclide}
\usepackage{tkz-elements}
\usepackage{luacode}

\begin{luacode}
-- Unicode Greek letter mapping to LaTeX
local greek_to_latex = {
  ["α"] = "\\alpha",
  ["β"] = "\\beta",
  ["γ"] = "\\gamma",
  ["δ"] = "\\delta",
  ["ε"] = "\\epsilon",
  ["ζ"] = "\\zeta",
  ["η"] = "\\eta",
  ["θ"] = "\\theta",
  ["ι"] = "\\iota",
  ["κ"] = "\\kappa",
  ["λ"] = "\\lambda",
  ["μ"] = "\\mu",
  ["ν"] = "\\nu",
  ["ξ"] = "\\xi",
  ["ο"] = "o",
  ["π"] = "\\pi",
  ["ρ"] = "\\rho",
  ["σ"] = "\\sigma",
  ["τ"] = "\\tau",
  ["υ"] = "\\upsilon",
  ["φ"] = "\\phi",
  ["χ"] = "\\chi",
  ["ψ"] = "\\psi",
  ["ω"] = "\\omega",
  -- Majuscules
  ["Α"] = "A",
  ["Β"] = "B",
  ["Γ"] = "\\Gamma",
  ["Δ"] = "\\Delta",
  ["Ε"] = "E",
  ["Ζ"] = "Z",
  ["Η"] = "H",
  ["Θ"] = "\\Theta",
  ["Ι"] = "I",
  ["Κ"] = "K",
  ["Λ"] = "\\Lambda",
  ["Μ"] = "M",
  ["Ν"] = "N",
  ["Ξ"] = "\\Xi",
  ["Ο"] = "O",
  ["Π"] = "\\Pi",
  ["Ρ"] = "P",
  ["Σ"] = "\\Sigma",
  ["Τ"] = "T",
  ["Υ"] = "\\Upsilon",
  ["Φ"] = "\\Phi",
  ["Χ"] = "X",
  ["Ψ"] = "\\Psi",
  ["Ω"] = "\\Omega"
}

function convert_greek_to_latex(char)
  local latex_char = greek_to_latex[char]
    tex.sprint("$" .. latex_char .. "$")
end
\end{luacode}

\newcommand{\convertGreek}[1]{%
  \directlua{convert_greek_to_latex("#1")}%
}

\def\tkzLabelGPoint[#1](#2){%
   \node[label style,#1] at (#2) {\convertGreek{#2}};
   }%
      
\begin{document}

Test: \convertGreek{α}, \convertGreek{β}

\vspace{12pt}
\begin{tikzpicture}
  \tkzDefPoint(1,2){α}
  \tkzDefPoint(3,1){β} 
  \tkzDrawLine(α,β)
  \tkzDrawPoints(α, β)
  \tkzLabelGPoint[red,below](α) 
  \tkzLabelGPoint[red,below](β)  
\end{tikzpicture}
\end{document}

So a direct answer to the question is

\documentclass{article}
\usepackage[mini]{tkz-euclide}
\usepackage{tkz-elements}

% stop expansion and use % not -- comments
\directlua{
%-- Unicode Greek letter mapping to LaTeX
local greek_to_latex = {
  ["α"] = "\string\\alpha",
  ["β"] = "\string\\beta",
  ["γ"] = "\string\\gamma",
  ["δ"] = "\string\\delta",
  ["ε"] = "\string\\epsilon",
  ["ζ"] = "\string\\zeta",
  ["η"] = "\string\\eta",
  ["θ"] = "\string\\theta",
  ["ι"] = "\string\\iota",
  ["κ"] = "\string\\kappa",
  ["λ"] = "\string\\lambda",
  ["μ"] = "\string\\mu",
  ["ν"] = "\string\\nu",
  ["ξ"] = "\string\\xi",
  ["ο"] = "o",
  ["π"] = "\string\\pi",
  ["ρ"] = "\string\\rho",
  ["σ"] = "\string\\sigma",
  ["τ"] = "\string\\tau",
  ["υ"] = "\string\\upsilon",
  ["φ"] = "\string\\phi",
  ["χ"] = "\string\\chi",
  ["ψ"] = "\string\\psi",
  ["ω"] = "\string\\omega",
  %-- Majuscules
  ["Α"] = "A",
  ["Β"] = "B",
  ["Γ"] = "\string\\Gamma",
  ["Δ"] = "\string\\Delta",
  ["Ε"] = "E",
  ["Ζ"] = "Z",
  ["Η"] = "H",
  ["Θ"] = "\string\\Theta",
  ["Ι"] = "I",
  ["Κ"] = "K",
  ["Λ"] = "\string\\Lambda",
  ["Μ"] = "M",
  ["Ν"] = "N",
  ["Ξ"] = "\string\\Xi",
  ["Ο"] = "O",
  ["Π"] = "\string\\Pi",
  ["Ρ"] = "P",
  ["Σ"] = "\string\\Sigma",
  ["Τ"] = "T",
  ["Υ"] = "\string\\Upsilon",
  ["Φ"] = "\string\\Phi",
  ["Χ"] = "X",
  ["Ψ"] = "\string\\Psi",
  ["Ω"] = "\string\\Omega"
}

function convert_greek_to_latex(char)
  local latex_char = greek_to_latex[char]
    tex.sprint("$" .. latex_char .. "$")
end
}

\newcommand{\convertGreek}[1]{%
  \directlua{convert_greek_to_latex("#1")}%
}

\def\tkzLabelGPoint[#1](#2){%
   \node[label style,#1] at (#2) {\convertGreek{#2}};
   }%
      
\begin{document}

Test: \convertGreek{α}, \convertGreek{β}

\vspace{12pt}
\begin{tikzpicture}
  \tkzDefPoint(1,2){α}
  \tkzDefPoint(3,1){β} 
  \tkzDrawLine(α,β)
  \tkzDrawPoints(α, β)
  \tkzLabelGPoint[red,below](α) 
  \tkzLabelGPoint[red,below](β)  
\end{tikzpicture}
\end{document}