Writing Scala after Java

Here is a list of rough edges that Scala polishes away, and the surprises that will stub the toe of expectation.

Different and better

• Pattern Matching. Just plain awesome. I hate switch blocks. I love matchers.
• Generics isn’t an after thought. I have always hated generics because dispite their utility they make my code look hideous.
• Check preconditions with require (p99)

Just different

• No static members. Scala uses companion objects to store singleton state. In usage the effect is minimal but you need to know how to write it.
• Operators are methods. Doesn’t affect your day to day usage. Allows for DSL’s. Precedence and notation are unchanged.
• implicit conversions. like autoboxing but more generally useful, and controllable.
• default scope is public, but who uses the default scope?

Stubbed toe different

• equals and == is reversed.
• If you forget to add the = in a def it means unit return. Combine that with the type inference and you get a method that doesn’t return what you think.
• order of mixins is important