Over the last few years we’ve had the opportunity to look at what closures are and basics how to create them in Perl & Raku. We even had a chance to look at how Raku’s more advanced signatures can improve closures there. Now it’s time to take a deeper look at how apply them. This talk will quickly review what we’ve see so far on how to define closures, then look at specific examples in testing and data processing where they can simplify frameworks used for CI, data munging, or general data processing