The Kotlin Primer has a new home

Hey everyone,

I’m extremely happy to announce that the Kotlin Primer has a new home at https://www.kotlinprimer.com/.

The Primer is an opinionated guide to the Kotlin language, and has successfully been used to migrate Java-centric organizations to Kotlin. It was previously hidden behind a paywall on Medium, but is now public for all to use.

What you can look forward to:

• ~100 chapters which will teach you Kotlin from the ground up, with even more to come. A lot of the stuff included isn’t trivial and is (to my knowledge) completely original. Ever wondered how to safely emulate dynamic dispatch? Or what actually makes a DSL a DSL? You likely know sequences are lazy and infinite, but do you know why? Are you aware that those properties are not randomly prescribed because they’re useful, but that they’re actually a consequence of something deeper? Have you ever wondered how pausing functions work? Do you know about kotlin.Result, and how to use it? Or maybe you’ve never really understood generics, and are looking for a completely novel explanation? All this, and much more, can be found in the Primer.
• Not only will you learn about Kotlin features, but you’ll learn when to use them, when not to use them, and most importantly, why. This, more than anything else, is what sets the Primer apart in my eyes – I do my best to dissect everything, and nothing is prescribed or taken blindly from the docs. Heck, I even disagree with them a few times!
• Everything is designed to promote maintainability, so you’ll be reading about design principles as well as language features
• Tons of curated links to outside material to further your understanding
• A hands-on approach using editable code snippets that you can execute right there, on the page complete with syntax highlighting, code completion, and similar IDE features
• Thought-out, non-trivial exercises to drive things home
• Searchable, navigable content
• It’s fast – First Contentful Paint is 0.9s on desktop!
• Mobile-friendly
• 235 easter eggs
• Best of all – it’s all free

Check it out, and let me know what you think!