什么是包？论文中的抽象语法

Question

在本文中 ”Haskell 的静态语义“显示了一种语言的模式，我想复制相同的风格，但我找不到正确的包。

我发现与包装有些相似，syntax但又有所不同。

这是一张纸的图片：

Answer 1

另一种解决方案，具有简单的tabular环境和uppunctlm包，它使用直立标点符号和斜体数字以及字体lm：

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{uppunctlm}
\usepackage{amsmath}
\usepackage{array, caption, booktabs}
\captionsetup{font = footnotesize}
\newcommand{\sub}[1]{\/\textsubscript{#1}}

\begin{document}

\begin{figure}
\centering
\fbox{%
\itshape\footnotesize\renewcommand{\arraystretch}{1.25}\setlength{\tabcolsep} {4pt}
 \begin{tabular}{r >{$}c<{$}l >{\upshape}l}
 \addlinespace[2.5ex]
 polytype & \to & context $ => $ monotype & \\
& \vert & monotype & \\[2ex]
 monotype & \to & tyvar & Type variable \\
& \vert & monotype\sub{1} –${>} $ monotype\sub{2} & Function type \\
 & \vert & [monotype] & List type \\
 & \vert & (monotype\sub{1},\,…, monotype\sub{n}) \quad $ (n=0\text{ or }n\ge2) $ & Tuple type (incl.\ unit) \\
 & \vert & tycon monotype\sub{1} … monotype\sub{n} \quad $ (n\ge0) $ & Constructed type \\[2ex]
 context & \to & class\/\sub{1} tyvar\sub{1},\,…, class\sub{n} tyvar\sub{n} \\
 \addlinespace[2.5ex]
  \end{tabular}}%
\caption{Abstract syntax of Haskell: types}
\end{figure}

\end{document} 

Answer 2

我不知道有哪个包有这么多的精妙之处。这是手工制作的版本。

\documentclass[a4paper]{article}
\usepackage{amsmath}
\usepackage{calc}

\newcommand{\mv}[1]{% metavariable
  \mathit{#1}%
}
\newcommand{\sor}{% syntax or
  \mathrel{\makebox[\widthof{$\to$}]{$|$}}%
}
\newcommand{\sTO}{\mathrel{\texttt{=>}}}
\newcommand{\sto}{\mathrel{\texttt{->}}}
\newcommand{\slp}{\mathopen{\texttt{(}}}
\newcommand{\srp}{\mathopen{\texttt{)}}}
\newcommand{\slb}{\mathopen{\texttt{[}}}
\newcommand{\srb}{\mathopen{\texttt{]}}}
\newcommand{\slc}{\mathpunct{\texttt{,}}}

\begin{document}

\begin{figure}
\centering

\footnotesize % adapt to your page size
\fbox{%
  $\begin{aligned}
  \mv{polytype} & \to  \mv{context} \sTO \mv{monotype}
  && \\
                & \sor \mv{monotype}
  && \\[2ex]
  \mv{monotype} & \to  \mv{tyvar}
  && \text{Type variable} \\
                & \sor \mv{monotype}_1 \sto \mv{monotype}_2
  && \text{Function type} \\
                & \sor \slb\mv{monotype}\srb
  && \text{List type} \\
                & \sor \slp\mv{monotype}_1\slc\dots\slc\mv{monotype}_n\srp
                       \quad (n=0\text{ or }n\ge2)
  && \text{Tuple type (incl.\ unit)} \\
                & \sor \mv{tycon}\,\mv{monotype}_1\dots\mv{monotype}_n
                       \quad (n\ge0)
  && \text{Constructed type} \\[2ex]
  context       & \to \slp\mv{class}_1\,\mv{tyvar}_1\slc\dots\slc\mv{class}_n\,\mv{tyvar}_n\srp
  \end{aligned}$%
}

\caption{Abstract syntax of Haskell: types}

\end{figure}

\end{document}

您可以通过更多的工作来获得更好的语法。

\documentclass[a4paper]{article}
\usepackage{amsmath}
\usepackage{calc,booktabs,xparse,environ}

% syntax symbols
\newcommand{\STO}{&\to}
\newcommand{\SOR}{&\mathrel{\makebox[\widthof{$\to$}]{$|$}}%
}
\newcommand{\REM}[1]{&&\text{#1}}

% Haskell symbols
\newcommand{\mv}[1]{\mathit{#1}}% metavariable
\newcommand{\hTO}{\mathrel{\texttt{=>}}}
\newcommand{\hto}{\mathrel{\texttt{->}}}
\newcommand{\hlp}{\mathopen{\texttt{(}}}
\newcommand{\hrp}{\mathopen{\texttt{)}}}
\newcommand{\hlb}{\mathopen{\texttt{[}}}
\newcommand{\hrb}{\mathopen{\texttt{]}}}
\newcommand{\hlc}{\mathpunct{\texttt{,}}}

\ExplSyntaxOn
\NewEnviron{haskellsyntax}
 {
  \tl_replace_all:Nnn \BODY { \par } { }
  $\begin{aligned}
  \haskell_syntax:V \BODY
  \end{aligned}$
 }
\cs_new_protected:Nn \haskell_syntax:n
 {
  \seq_clear:N \l_haskell_syntax_output_seq
  \seq_set_split:Nnn \l_haskell_syntax_body_seq { \\ } { #1 }
  \seq_map_inline:Nn \l_haskell_syntax_body_seq
   {
    \seq_set_split:Nnn \l_haskell_syntax_row_seq { \SOR } { ##1 }
    \seq_put_right:Nx \l_haskell_syntax_output_seq
     {
      \seq_use:Nn \l_haskell_syntax_row_seq { \haskell_syntax_break: }
      \exp_not:N \\
     }
   }
  \seq_use:Nn \l_haskell_syntax_output_seq { \addlinespace }
 }
\cs_generate_variant:Nn \haskell_syntax:n { V }
\cs_new_protected:Nn \haskell_syntax_break: { \\ \SOR }
\ExplSyntaxOff

\begin{document}

\begin{figure}
\centering

\footnotesize % adapt to your page size
\fbox{%
  \begin{haskellsyntax}
  \mv{polytype} \STO \mv{context} \hTO \mv{monotype}
                \SOR \mv{monotype}
  \\
  \mv{monotype} \STO  \mv{tyvar}
                      \REM{Type variable}
                \SOR  \mv{monotype}_1 \hto \mv{monotype}_2
                      \REM{Function type}
                \SOR  \hlb\mv{monotype}\hrb
                      \REM{List type}
                \SOR  \hlp\mv{monotype}_1\hlc\dots\hlc\mv{monotype}_n\hrp
                      \quad (n=0\text{ or }n\ge2)
                      \REM{Tuple type (incl.\ unit)}
                \SOR  \mv{tycon}\,\mv{monotype}_1\dots\mv{monotype}_n
                      \quad (n\ge0)
                      \REM{Constructed type} 
  \\
  context       \STO \hlp\mv{class}_1\,\mv{tyvar}_1\hlc\dots\hlc\mv{class}_n\,\mv{tyvar}_n\hrp
  \end{haskellsyntax}%
}

\caption{Abstract syntax of Haskell: types}

\end{figure}

\end{document}