And the defs file

defs.tex

@@ -0,0 +1,29 @@
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\newcommand{\itm}[1]{\ensuremath{\mathit{#1}}}
+\newcommand{\Stmt}{\itm{stmt}}
+\newcommand{\Exp}{\itm{exp}}
+\newcommand{\Instr}{\itm{instr}}
+\newcommand{\Prog}{\itm{prog}}
+\newcommand{\Arg}{\itm{arg}}
+\newcommand{\Int}{\itm{int}}
+\newcommand{\Var}{\itm{var}}
+\newcommand{\Op}{\itm{op}}
+\newcommand{\key}[1]{\texttt{#1}}
+\newcommand{\READ}{(\key{read})}
+\newcommand{\UNIOP}[2]{(\key{#1}~#2)}
+\newcommand{\BINOP}[3]{(\key{#1}~#2~#3)}
+\newcommand{\LET}[3]{(\key{let}~([#1\;#2])~#3)}
+
+\newcommand{\ASSIGN}[2]{(\key{assign}~#1\;#2)}
+\newcommand{\RETURN}[1]{(\key{return}~#1)}
+
+\newcommand{\INT}[1]{(\key{int}\;#1)}
+\newcommand{\REG}[1]{(\key{reg}\;#1)}
+\newcommand{\VAR}[1]{(\key{var}\;#1)}
+\newcommand{\STACKLOC}[1]{(\key{stack}\;#1)}
+
+\newcommand{\IF}[3]{(\key{if}\,#1\;#2\;#3)}
+
+\newcommand{\TTKEY}[1]{\normalfont\tt\key{#1}}
+