Home » Author Archives: Jakub Holy

Author Archives: Jakub Holy

Jakub is an experienced Java[EE] developer working for a lean & agile consultancy in Norway. He is interested in code quality, developer productivity, testing, and in how to make projects succeed.

An answer to CircleCI’s Why we’re no longer using Core.typed


CircleCI has recently published a very useful post “Why we’re no longer using Core.typed” that raises some important concerns w.r.t. Typed Clojure that in their particular case led to the cost overweighting the benefits. CircleCI has a long and positive relation to Ambrose Bonnaire-Sergeant, the main author of core.typed, that has addressed their concerns in his recent Strange Loop talk “Typed ...

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There will be failures – On systems that live through difficulties instead of turning them into a catastrophy


Our systems always depend on other systems and services and thus may and will be subject to failures – network glitches, dropped connections, load spikes, deadlocks, slow or crashed subsystems. We will explore how to create robust systems that can sustain blows from its users, interconnecting networks, and supposedly allied systems yet carry on as well as possible, recovering quickly ...

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Challenging Myself With Coplien’s Why Most Unit Testing is Waste


James O. Coplien has written in 2014 the thought-provoking essay Why Most Unit Testing is Waste and further elaborates the topic in his Segue. I love testing but I also value challenging my views to expand my understanding so it was a valuable read. When encountering something so controversial, it’s crucial to set aside one’s emotions and opinions and ask: “Provided ...

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Surfacing Hidden Design: Seeking A Better Alternative To Interrelated Mutable Fields


What is better, a bunch of mutable boolean fields and methods operating on them, or an explicit expression of the individual states and transitions between them? Lets study an example from a simulation of the progression of a multi-stage infection. 1. Design hidden in primitive mutable fields and methods The following class, with a number of interrelated mutable (public) fields, ...

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