Scala Style Guide

This document is intended to outline some basic Scala stylistic guidelines which should be followed with more or less fervency. Wherever possible, this guide attempts to detail why a particular style is encouraged and how it relates to other alternatives. As with all style guides, treat this document as a list of rules to be broken. There are certainly times when alternative styles should be preferred over the ones given here.

• Indentation
  • Line Wrapping
  • Methods with Numerous Arguments
• Naming Conventions
  • Classes/Traits
  • Objects
  • Packages
    • root
  • Methods
    • Accessors/Mutators
    • Parentheses
    • Symbolic Method Names
  • Constants, Values and Variables
  • Type Parameters (generics)
    • Higher-Kinds and Parameterized Type parameters
  • Annotations
  • Special Note on Brevity
• Types
  • Inference
    • Function Values
  • Annotations
  • Ascription
  • Functions
    • Arity-1
  • Structural Types
• Nested Blocks
  • Curly Braces
  • Parentheses
• Declarations
  • Classes
    • Ordering Of Class Elements
    • Methods
      • Procedure Syntax
      • Modifiers
      • Body
      • Multiple Parameter Lists
      • Higher-Order Functions
    • Fields
  • Function Values
    • Spacing
    • Multi-Expression Functions
• Control Structures
  • Curly-Braces
  • Comprehensions
  • Trivial Conditionals
• Method Invocation
  • Arity-0
  • Arity-1 (Infix Notation)
    • Symbolic Methods/Operators
    • Higher-Order Functions
• Files
  • Multi-Unit Files
• Scaladoc
  • General Style
  • Packages
  • Classes, Objects, and Traits
    • Classes
    • Objects
    • Traits
  • Methods and Other Members

Thanks to

Daniel Spiewak and David Copeland for putting this style guide together, and Simon Ochsenreither for converting it to Markdown.