G'day wsly,

Welcome to the Monastery.

[That's an unfortunate choice of example module names as B already exists and is a core module. I'm going to pretend you wrote X and Y. You may want to change that in your post; How do I change/delete my post? explains how to do this.]

There's a number of ways to do this. Please tell us about the relationship between these two modules. Here's some possibilities:

• X exports functions; Y imports them.
• Y is a subclass of X: an inheritance relationship.
• X is a component of Y: a composition relationship.
• X is an optional feature of Y: an aggregation relationship.

You may want to look at Exporter for the first of those relationships; or "perlootut - Object-Oriented Programming in Perl Tutorial" for the remainder.