    \documentclass{article}

    \usepackage{agda}
    \AgdaNoSpaceAroundCode{}

    \begin{document}

    \hrule
    \begin{code}
    postulate

      A : Set
      B : Set
    \end{code}
    \hrule
    \begin{code}

    \end{code}
    \hrule
    \begin{code}

    \end{code}
    \hrule
    \begin{code}
    \end{code}
    \hrule
    \begin{code}
      \end{code}
    \hrule
      \begin{code}
    \end{code}
    \hrule
      \begin{code}
        \end{code}
    \hrule
    \begin{code}
    module _ where
    \end{code}
    \begin{code}

      postulate
        C : Set
    \end{code}
    \hrule
    \begin{AgdaAlign}
    \begin{code}
    postulate
      F  : Set → Set
      X  : F
    \end{code}
    \begin{code}
              A
    \end{code}
    \end{AgdaAlign}
    \hrule

    \end{document}