This document provides style guidelines for Scala developers at Twitter. It outlines recommendations for imports, implicit usage, reflection, comments, whitespace, logging, project layout, variable naming conventions, and ends by thanking people for attending.

1. BAY AREA SCALA ENTHUSIASTS
WELCOME TO TWITTER!
HELP YOURSELF TO BEER AND SUCH IN THE KITCHEN.

2. ROBEY
STEVE
ALEX
TWITTER’S SCALA HEADS

3. STYLE GUIDELINES

4. IMPORTS
ENUMERATE ALL ALL IMPORTS MUST BE
IMPORTS AT THE TOP OF THE
FILE
USE WILDCARDS FOR
MORE THAN SIX
USE BRACE NOTATION
FOR MULTIPLE ITEMS
IN A PACKAGE
AVOID “RELATIVE”
IMPORTS

5. IMPLICITS
AVOID THEM!
THEY MAKE DEBUGGING CONFUSING
DOCUMENT THOROUGHLY IF YOU HAVE TO USE THEM
RESTRICT TO THE SMALLEST POSSIBLE SCOPE

6. REFLECTION (JAVA)
AVOID IT!
SLOW
POTENTIALLY CONFUSING

7. COMMENTS
MANDATORY
VSCALADOC
SCALADOC EVERY CLASS AND NON-TRIVIAL METHOD
WRITE IN PASSIVE VOICE, EX:
“RETURNS A LIST[STATUS] OF 20 STATUSES FOR THE
GIVEN USER.”

8. WHITESPACE
2 SPACES, NO TABS
NO TRAILING WHITESPACE
KEEP LINES TO 100 COLUMNS MAX

9. LOGGING
USE ONLY JAVA.UTIL.LOGGING.LOGGER
NOTHING GOES TO STDOUT/STDERR
NAME THE LOGGING OBJECT/VARIABLE “LOG”

10. PROJECT LAYOUT
MAVEN CONVENTIONS FOR DIRECTORY STRUCTURE, EX:
SRC/[MAIN|TEST]/[SCALA|JAVA]/COM/TWITTER/FOO
DEPLOY JARS
USE ANT + IVY AS THE BUILD SYSTEM

11. VARIABLE NOMENCLATURE
DON’T EXCESSIVELY ABBREVIATE VARIABLE NAMES
IT’S OKAY TO USE I, J, K, ETC. FOR INDICES
USE “RV” FOR TEMPORARY RETURN VALUES

12. THANKS FOR COMING!