In a new post to his site Fabian Schmengler has written up an introduction to collection pipelines and how it could be applied to a Magento-based environment.

If you read the book “Refactoring to Collections” or saw screencasts and talks by Adam Wathan about collection pipelines, but do not work with Laravel, you might have asked yourself how to apply these techniques to other PHP applications, for example Magento.

[...] This is very similar to Unix pipes, where the individual commands are the operations, and the lines passed through input and output stream, the collection.

He starts by illustrating the idea in Bash and Ruby, showing the three main types of collection operations: map, filter and reduce. He talks about the advantages these methods have over traditional looping and what kind of value they can provide in both Laravel and plain old PHP. He illustrates the PHP-only versions using the array_filter, array_map and array_reduce functions and some thoughts on when it's good to use them over normal looping (and when it's not). He then gets into the Magento-specific handling and making use of a package to handle collections: Knapsack. He shows how to use the library to work with collections and, as another option, a "home-grown" version that lives in a single class. The post wraps up with the Magento integration of this functionality, a brief mention of functional programming and "the hard part" of issues with debugging.