Functional Principles for OO Development
summary
Claims six functional principles apply to OO Ruby and shows them on the Pickaxe CSV total example: replaces a god object with pure data-in data-out functions, implements an Either wrapper for errors instead of nil, uses Ruby 2.0 stabby lambdas and ARGV.lazy streaming pipeline to process files one record at a time, removes mutable state, preserves rejected-row information, and produces a single-pass total and error counts with no global side effects; code is on GitHub.
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