Use functions in Pl/Perl language

Hello,

I would like to create a function that lets me to search in a table
rows according differents parameters.
I looked in the documentation of postgresql 8.1 about Pl/Perl
procedures but I didn't found how to cross each row of a table with
Pl/Perl.

Someone would have an example of that with Pl/Perl language ?

Thanks to help me.

Sylvain.