+++ /dev/null
-\chapter{What {\tt pphs} does}
-
-This chapter describes a program called {\tt pphs} which implements the typesetting
-requirements described in the previous chapter. The description is from the user's viewpoint,
-later chapters going on to describe it from that of the programmer.
-
-The {\tt pphs} program typesets Haskell programs for use with the \LaTeX\
-typesetting program. It takes as input a file containing a Haskell
-program and produces the Haskell code to {\tt stdout}. It is called by
-typing {\tt pphs}, followed by the name of the file containing the Haskell
-program. For example, if the Haskell program was in a file called {\tt Haskell.hs},
-the program would be called by
-\begin{quote}
-\tt pphs Haskell.hs
-\end{quote}
-
-If the filename ends with a {\tt .hs} extension, the extension may be omitted, provided
-there is no file already existing with the same name but with no extension. If no
-extension is given with the filename when called, the program will look for a file of
-that name with no extension. If this is not found, the program will add a {\tt .hs}
-extension. The above example, therefore, may be simplified to
-\begin{quote}
-\tt pphs Haskell
-\end{quote}
-unless the file {\tt Haskell} exists, in which case the original call must be made.
-
-As the output of {\tt pphs} is to {\tt stdout}, it may be directed to a file by using
-the {\tt >} command after the call, followed by the name of the file to contain
-the \LaTeX\ code. Continuing the above example, if the output code is to be put into
-a file called {\tt Haskell.tex}, the call would now be
-\begin{quote}
-\tt pphs Haskell.hs > Haskell.tex
-\end{quote}
-It must be noted that if the file {\tt Haskell.tex} already exists, it should be
-renamed or removed before making this call.
-
-Two options are allowed with the call. In the output, some people prefer \label{wide-colons}
-the {\tt ::} symbol to be written $:\,:$ rather than $::$. To obtain the former, use
-{\tt -w} for wide colons. A call on {\tt Haskell.hs} requiring wide colons would be
-\begin{quote}
-\tt pphs -w Haskell.hs
-\end{quote}
-When the input file's tab characters are not of the standard 8 spaces, this can be
-specified with the {\tt -t} command. For example, if the tabs were 4 spaces long, type
-\begin{quote}
-\tt pphs -t4 Haskell.hs
-\end{quote}
-Both options can be used at the same time by calling
-\begin{quote}
-\tt pphs -t4w Haskell.hs
-\end{quote}
-or
-\begin{quote}
-\tt pphs -wt4 Haskell.hs
-\end{quote}
-Any positive integer can be specified for the tablength.
-
-\section{Left indentation}
-
-It is in the nature of Haskell programs that indentation is heavily used. As the
-indentation is vital to the parsing of the program, any attempt at typesetting
-Haskell code must replicate this indentation. Take, for example, the following piece of code.
-\begin{quote}
-\input{Haskell_leftindent1}
-\end{quote}
-Note how the third and fourth lines both start at different levels of indentation.
-The {\tt pphs} program produces the correct \LaTeX\ code to align these under the
-correct position in the preceding lines once typeset. It also selects the correct
-line to line up under. Note how, in the following example, the sixth line does not line up
-under its predecessor, but under the fourth line.
-\begin{quote}
-\input{Haskell_leftindent2}
-\end{quote}
-Again, {\tt pphs} produces the code necessary to typeset this, preserving the parsing
-order. A line of Haskell code may be indented beyond the end of its predecessor.
-Here, {\tt pphs} aligns it with whichever line it is lined up underneath in the
-original file. Note that these
-examples of possible input have no `extra' typesetting commands.
-
-\section{Internal alignment}
-
-Another form of alignment used in Haskell is {\em internal alignment}. This is where
-there is vertical alignment of columns other than at the left-hand edge of the
-Haskell code.
-\begin{quote}
-\input{Haskell_internalalign1}
-\end{quote}
-In this example, see how the {\tt =} signs line up, one below the other. This makes
-the program more readable, although it does not affect the parsing of the program.
-As the purpose of {\tt pphs} is to make Haskell programs even more readable, it
-retains this alignment.
-
-\section{Token highlighting}
-
-To increase the readability of Haskell programs, {\tt pphs} allows various tokens
-to be highlighted. By using different typefaces for some pieces of code, this
-distinguishes them from the rest. The user can specify the details of the highlighting as
-described in Section~\ref{user-adj}, but the default settings are {\bf bold} for
-keywords, {\it italics} for identifiers and {\rm roman} for everything else. Strings,
-comments and numbers are also highlightable (see Section~\ref{user-adj}).
-
-\section{Mathematical symbols}
-
-Rather than simply replicate the ASCII approximations of mathematical symbols
-used in Haskell, {\tt pphs}
-substitutes the proper symbols in the output. These are shown in Table~\ref{maths-sym}.
-\begin{table}
-\begin{center}
-\begin{tabular}[t]{|c|c|} \hline
-{\em Haskell\/} & {\em Math\/} \\ \hline
-{\tt *} & $\times$ \\
-{\tt ++} & {\hbox{$+\mkern-7.5mu+$}} \\
-{\tt :+} & {:}{+} \\
-{\tt <=} & $\leq$ \\ \hline
-\end{tabular} \hskip3mm \begin{tabular}[t]{|c|c|} \hline
-{\em Haskell\/} & {\em Math\/} \\ \hline
-{\tt >=} & $\geq$ \\
-{\tt <-} & $\leftarrow$ \\
-{\tt ->} & $\rightarrow$ \\
-{\tt =>} & $\Rightarrow$ \\ \hline
-\end{tabular}
-\end{center}
-\caption{Haskell ASCII approximations to mathematical characters} \label{maths-sym}
-\end{table}
-
-\section{\LaTeX\ typesetting characters}
-
-\LaTeX\ uses embedded typesetting commands, so {\tt pphs} has to ensure that if
-any of the characters used by \LaTeX\ appear in the input Haskell code, the correct
-\LaTeX\ code is outputted to typeset them, rather than have the characters interfere
-with the typesetting process. The characters used by \LaTeX\ for typesetting are:
-\begin{quote}
-\(\#\ \$\ \%\ \&\ \char'176\ \_\ \char'136\ \hbox{$\setminus$}\ \hbox{$\cal \char'146\ \char'147$}\)
-\end{quote}
-The user of {\tt pphs} need not worry about using any of these characters in Haskell
-programs, as this will be dealt with by {\tt pphs} before \LaTeX\ gets to see the code.
\ No newline at end of file
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