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<H1><A NAME="SECTION00090000000000000000"> </A>
<A NAME="sec:cook"> </A>
<BR>
Cookbook
</H1>
The term processor <EM>Kimwitu</EM> supports a number of styles of programming functions
over trees.
Such styles are sometimes called <EM>paradigms</EM><A NAME="1071"> </A>, and we can therefore say that the
term processor supports <EM>multi-paradigm programming</EM>.
In this section we try to substantiate this claim by presenting some examples.
Each of these examples highlights a particular paradigm, some also show how paradigms
can be mixed.
<P>
The most fundamental paradigm of course is that of trees, and in particular trees in
which nodes of various types appear.
This structure appears in a number of ways in computer science.
<EM>Parse tree</EM> nodes correspond to the terminal and non-terminal symbols of a context-free language,
or more precisely, production instances of those symbols.
Normally an abstraction of parse trees is used, in which irrelevant terminal symbols and non-terminal
symbols are eliminated.
Such trees are usually called <EM>abstract syntax trees</EM>.
In abstract data type theory, trees denote <EM>expressions</EM> and a normal form of an expression
denotes its <EM>value</EM> in a certain sense.
Trees can also represent a prescription of the computation of a value,
or more general, a <EM>program</EM>.
<P>
The reason for mixing paradigms is that we want to exploit the strong points of each paradigm,
while at the same time avoiding their weak points.
Examples of such weak points are the following.
Attribute grammars allow only attributes to be computed over trees, where the computation
can not have a circular dependency.
Functional programming languages do not allow side effects to be expressed.
Abstract data type rewrite systems can only rewrite terms to their normal form.
Conventional programming languages, such as C,
usually force the programmer to be fairly aware
of the representation of data types.
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<BR><I>2000-04-17</I>
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