delimiters.sty

% https://tex.stackexchange.com/questions/1742/automatic-left-and-right-commands/1744#1744
\RequirePackage{amsmath}
\RequirePackage{mathtools}

% delim sizing options
\let\delim@autol\left  \let\delim@autor\right \let\delim@autom\middle
\let\delim@basel\relax \let\delim@baser\relax \let\delim@basem\relax
\let\delim@bigl\bigl   \let\delim@bigr\bigr   \let\delim@bigm\big
\let\delim@Bigl\Bigl   \let\delim@Bigr\Bigr   \let\delim@Bigm\Big
\let\delim@biggl\biggl \let\delim@biggr\biggr \let\delim@biggm\bigg
\let\delim@Biggl\Biggl \let\delim@Biggr\Biggr \let\delim@Biggm\Bigg

% default definitions
\newcommand\ldelim{\relax}
\newcommand\rdelim{\relax}
\newcommand\mdelim{\relax}

% the actual command
\newcommand\delim@command[4]{{%   #1 size #2 ldelim #3 rdelim #4 content
    \def\ldelim{\csname delim@#1l\endcsname}%
    \def\rdelim{\csname delim@#1r\endcsname}%
    \def\mdelim{\csname delim@#1m\endcsname}%
\ldelim#2#4\rdelim#3}}

% a factory to define new delimiter commands
\newcommand{\newdelimcommand}[3]{% #1 name #2 ldelim #3 rdelim
    \expandafter\newcommand\csname delim@#1@st\endcsname[1]{% ##1 content
    \delim@command{base}{#2}{#3}{##1}}%
    \expandafter\newcommand\csname delim@#1@ns\endcsname[2][auto]{%
    % ##1 size ##2 content
    \delim@command{##1}{#2}{#3}{##2}}%
    \expandafter\DeclareRobustCommand\csname#1\endcsname{%
        \@ifstar{\csname delim@#1@st\endcsname}{\csname delim@#1@ns\endcsname}%
    }%
}

% syntactically named delimiters
\newdelimcommand{ceil}{\lceil}{\rceil}
\newdelimcommand{floor}{\lfloor}{\rfloor}
\newdelimcommand{angles}{\langle}{\rangle}
\newdelimcommand{parens}{\lparen}{\rparen}
\newdelimcommand{bracket}{[}{]}
\newdelimcommand{braces}{\lbrace}{\rbrace}
\newdelimcommand{verts}{\lvert}{\rvert}
\newdelimcommand{Verts}{\lVert}{\rVert}

% semantically named delimiters
\newcommand{\set}{\braces}
\newcommand{\abs}{\verts}
\newcommand{\size}{\verts}
\newcommand{\norm}{\Verts}
\newcommand{\tuple}{\angles}
\newcommand{\iprod}{\angles}

% Automagic `such that' for set comprehension. Inside an automagic
% delimiter command, the vertical bar will resize appropriately
% Example:
%   \set{ x \in W \given x > 0 }
\newcommand{\given}{\;\mdelim\vert\;}