OverviewSource FilesNamingCommon NamesIndentionStatementsComments


These are the coding conventions we've used in the Fantom code base. By no means are you required to follow our conventions - they are documented just in case you care. However these conventions are enforced if contributing code for the core distribution.

Source Files

  • Use 7-bit safe ASCII as clean subset of UTF-8
  • Use Unix "\n" line endings
  • Prefer putting class FooBar in a source file called ""
  • If you have a bunch of little classes, coalesce into a single source
  • Separate test classes into separate "test/" directory


  • Type names are upper camel case such as "FooBar"
  • Slot names are lower camel case such as "fooBar" (this includes all fields and methods, even const fields)
  • Never use screaming caps such as "FOO_BAR"
  • Symbol names are lower camel case
  • Pod names are lower camel case and globally unique. You should prefix your pod names with something to avoid naming conflicts. For example a SourceForge or Google Code project name is a safe naming convention. Or prefix pods with an organization or domain name. If you own a ".com" domain, don't include the "com" in your pod names.
  • Don't use words which are fully capitalized in your identifiers:
    • Use "someId" instead of "someID"
    • Use "readXml" instead of "readXML"

Common Names

  • Prefer add to append
  • Prefer addr to address
  • Prefer arg to argument
  • Prefer cur to current
  • Prefer dotnet/Dotnet
  • Prefer err to error
  • Prefer html/Html to HTML
  • Prefer http/Http to HTTP
  • Prefer id/Id to ID or Identifier
  • Prefer io/IO to Io
  • Prefer loc to location
  • Prefer msg to message
  • Prefer param to parameter
  • Prefer rec to record
  • Prefer req to request
  • Prefer res to response
  • Prefer res to resource
  • Prefer ro/RO to Ro
  • Prefer rw/RW to Rw
  • Prefer size to length or count
  • Prefer src to source
  • Prefer username to userName
  • Prefer val to value
  • Prefer warn to warning
  • Prefer xml/Xml to XML


  • Do not use tab characters, use spaces only
  • Use two space indention
  • Use Allman styling braces:
    if (cond)
  • Prefer a single statement on each line with no semicolon
  • Collapse statements onto a single line if they are short and it aids readability
  • Leave one space between keyword and opening paren in if, for, while, switch, and catch statements


  • Always omit () for method calls with no arguments
  • Prefer Foo(...) style constructor with arguments
  • Prefer Foo {...} style constructor when using it-block
  • Prefer type inference for local variables
  • Prefer implicit casting to explicit casting
  • Prefer Obj[] to List and Obj:Obj to Map
  • Prefer to omit return keyword in single statement methods and closures


  • Use /* */ comments only for commenting out sections of code
  • Prefer to use a leading and trailing ** line in a fandoc comment unless the comment is short:
    class Foo
      ** This is a very well written comment
      Void doSomethingCool() {}
  • Break logical sections up using line of 74 / chars:
    // Section
  • Use line of 74 * chars to separate classes in a single source file:
    ** NewClass
  • We use the following comment at the top of each source file (obviously the names will be different for you):
    // Copyright (c) 2008, Brian Frank and Andy Frank
    // Licensed under the Academic Free License version 3.0
    // History:
    //   28 Aug 08  Brian Frank  Creation