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Here is my presentation webinar on the Arrow Core for experienced Java developers, who are unfamiliar with functional programming (FP) and also migrating from Java to Kotlin.

YouTube – I am a technical leader / principal engineer. It is part of daily duty to improve the working lives of software developers in teams, especially where I am accountable for the efficiency and productivity.

Arrow is handy tool in your FP toolbox that I help teams understand and apply correctly in my coaching.

This presentation demonstrates:

• How to move from hidden failures → nullable results → fully typed outcomes=
• The type signature Either<String, Double> tells the whole story – it can succeed with a Double or fail with a String message
• I help Java teams make exactly this kind of mindset shift in my coaching
• If you are brave enough I also touch the tricky subject of Ior<E, A>

Thoughts? comments? I will accept your feedback graciously, especially please reached for Java Tech Coaching for yourself or your teams.

Please find the Slide deck (PDF) here

Please find the source code for this Webinar in the arrowkt-webinar-2025 Github repository.

Peter Pilgrim, +PP+, November 2025

Coda: What did I learn? Use much better streaming technology. Setup a secure and psychological safe event meeting environment for developers who are really interested in computer programming. See you at the next event.