pseudo.sty

The pseudo package permits writing pseudocode without much fuss and with quite a bit of configurability. Its main environment combines aspects of enumeration, tabbing and tabular for nonintrusive line numbering, indentation and highlighting, and there is functionality for typesetting common syntactic elements such as keywords, identifiers and comments.

The package is written by Magnus Lie Hetland and released under the MIT license.

Using pseudo

You can find more detailed instructions in the documentation, but it's really quite simple to get started. The package is available via CTAN, and so is part of several TeX distributions. If the newest version isn't in yours, try to run an update. In TeX Live, for example, you could run use the TeX Live Utility (part of distributions such as MacTeX). Alternatively, you can just download the pseudo.sty file and drop it where your latex can find it (possibly just in the same directory as your document).

Assuming you want numbered lines (the default) and have most text set as keywords (set by the kw switch), you simply import pseudo using

\usepackage[kw]{pseudo}

and then set your pseudocode in a pseudo environment. Lines are terminated by the normal \\ command, which may be extended with one or more pluses or minuses to indicate a change in indentation level. You suppress the automatic numbering of the following line using a star (i.e., either \\*, or \begin{pseudo}*), and can typeset a procedure header using \hd{Name}(...). For example:

\begin{pseudo}*

    \hd{Backward}(V, E, v, i) \\

    $v.\id{label} = i$ \\

    for $(u,v)\in E$ \\+
        if $0 < v.\id{label} < i$ \\+
            \pr{Backward}(V, E, u, i) \\--

    for $(u,v)\in E$ \\+
        if $u.\id{label} \== 0$ \\+
            \pr{Backward}(V, E, u, i+1)

\end{pseudo}

This produces:

There is also a starred version of the environment (pseudo*), which is unnumbered.

The commands \pr and \id indicate procedure calls and identifiers. If we hadn't used the kw option, the main text would not be set as keywords, but as plain text. We could then use \kw to mark up keywords. Some of these may be used a lot, so I might want to declare a shortcut. For example, if I use

\DeclarePseudoKeyword \While {while}

I'd be able to use \While rather than \kw{while} later. Several such formatting and declaration commands exist:

Type of text	Command	Declaration
Keywords	\kw{while}	\DeclarePseudoKeyword \While {while}
Constants	\cn{false}	\DeclarePseudoConstant \False {false}
Identifiers	\id{rank}	\DeclarePseudoIdentifier \Rank {rank}
Strings	\st{Hello!}	\DeclarePseudoString \Hello {Hello!}
Procedures	\pr{Euclid}(a, b)	\DeclarePseudoProcedure \Euclid {Euclid}
Functions	\fn{length}(A)	\DeclarePseudoFunction \Length {length}
Comments	\ct{Important!}	\DeclarePseudoComment \Important {Important!}

For normal text (e.g., when using the kw switch), there is also \tn (along with \DeclarePseudoNormal).

Since the short names of these commands are prone to collisions with other packages, pseudo won't insist on using them. If you import pseudo after some other package that already uses, say, \id, then pseudo won't define it. All of these are still available with the pseudo prefix, however (e.g., \pseudoid), and the declaration commands still work.

Beyond the styling of text, there are also the \== and \.. commands (also written \eqs and \dts) for typesetting double equals sign and double dots.

This covers most of the core functionality, but there are also more obscure features (such as dimming or highlighting lines), support for algorithm floats (and inline boxes) with customizable numbering and appearance, and a host of configuration keys for getting the pseudocode looking more like you'd want it to. For details, consult the documentation.