Unsafe patterns

We’re now tackling parts of Scala that are actively unsafe to use: misusing them will cause programs not to terminate, or to break in truly incomprehensible ways.

Readers should pay attention to these rules, as in my experience even advanced developers sometimes fail to heed some of them.

Content

• Avoid implicit conversions
• Avoid structural types
• Do not compare arrays with ==
• Do not compute the size of a collection to check for emptiness
• Do not return Option from custom extractors
• Do not use null
• Make recursive functions tail-recursive
• Mark tail-recursive functions as such