4.1 How to define new macros

The normal way to define or redefine macros is to use the builtin \define:

\define{name}{parameters}{expansion}

which defines name to expand to expansion.

The following example defines the macro \foo to expand to the text `Hello World.'.

\define\foo{}{Hello world.} => \foo =>Hello world.

parameters is used to tell how the macro accepts arguments. It consists of numbers followed by #. Each argument is referred by #-number in expansion. For example:

\define\bar{#1}{Good #1.} => \bar{morning} =>Good morning.

A parameter can be followed by an optional delimiters (a character). If an optional delimiters is given, text from point to the character is regarded as an argument. For example:

\define\baz{#1/}{#1.} => \baz This is an argument/ =>This is an argument.

A macro definition can be removed with undefine:

\undefine{name}

which removes the macro name.