lhs2tex-1.12: Examples/CalcExample.lhs
\documentclass{article}
%include lhs2TeX.fmt
%include lhs2TeX.sty
%include polycode.fmt
\newenvironment{calculation}{%
\renewcommand\commentbegin{\qquad\{\ }%
\renewcommand\commentend{\}}%
\setlength{\blanklineskip}{1ex}%
\renewcommand\hsindent[1]{\qquad}}{}
\begin{document}
\begin{calculation}
\begin{spec}
map (+1) [1,2,3]
== {- desugaring of |(:)| -}
map (+1) (1 : [2,3])
== {- definition of |map| -}
(+1) 1 : map (+1) [2,3]
== {- performing the addition on the head -}
2 : map (+1) [2,3]
== {- recursive application of |map| -}
2 : [3,4]
== {- list syntactic sugar -}
[2,3,4]
\end{spec}
\end{calculation}
\end{document}