Scalariform is a code formatter for Scala 2.8. It is a stand-alone library and an Eclipse plug-in. Currently, Scalariform supports only a limited set of options, although it is intended to be compatible with the recommendations of the Scala Style Guide (see below). Please let me know what other features people would like.
Scalariform is licenced under The MIT Licence.
In Eclipse Ganymede (3.5), install the latest nightly Scala Eclipse plugin using the Eclipse update site mechanism:
http://www.scala-lang.org/scala-eclipse-plugin-nightly
(See http://www.scala-lang.org/node/94 for more detailed instructions.)
Then install Scalariform from this update site:
http://scalariform.googlecode.com/svn/trunk/update-site/
To format:
- Right click in the editor -> Format Scala Source Code, or
- Press Ctrl-Shift-D
To configure preferences, go to Window -> Preferences -> Scala -> Scala Formatter Preferences
Default: false
Align class/function parameters in the same column. For example, if false, then:
class Person(name: String, age: Int, birthdate: Date, astrologicalSign: String, shoeSize: Int, favoriteColor: java.awt.Color)
If true, then:
class Person(name: String,
age: Int,
birthdate: Date,
astrologicalSign: String,
shoeSize: Int,
favoriteColor: java.awt.Color)
Default: false
Omit spaces when formatting a '+' operator on String literals". For example, If false, then:
"Hello " + name + "!"
If true, then:
"Hello "+name+"!"
The Scala Style Guide recommends that operators, "should always be invoked using infix notation with spaces separated the target".
Default: false
With this set to true, class (and trait / object) declarations
will be formatted as recommended by the Scala Style Guide. That is,
if the declaration section spans multiple lines, it will be formatted
so that either the parameter section or the inheritance section is
doubly indented. This provides a visual distinction from the members
of the class. For example:
class Person(
name: String,
age: Int,
birthdate: Date,
astrologicalSign: String,
shoeSize: Int,
favoriteColor: java.awt.Color)
extends Entity
with Logging
with Identifiable
with Serializable {
def firstMethod = ...
}
Or:
class Person(
name: String,
age: Int,
birthdate: Date,
astrologicalSign: String,
shoeSize: Int,
favoriteColor: java.awt.Color) {
def firstMethod = ...
}
Default: 2
The number of spaces to use for each level of indentation.
Default: false
If true, the formatter will keep an existing space before a parenthesis argument. For example:
stack.pop() should equal (2)
Otherwise, if false, spaces before arguments will always be removed.
Default: false
Replace arrow tokens with their unicode equivalents: => with ⇒, and <- with ←. For example:
for (n <- 1 to 10) n % 2 match {
case 0 => println("even")
case 1 => println("odd")
}
is formatted as:
for (n ← 1 to 10) n % 2 match {
case 0 ⇒ println("even")
case 1 ⇒ println("odd")
}
Default: false
Whether to ensure a space before colon. For example, If false, then:
def add(a: Int, b: Int): Int = a + b
If true, then:
def add(a : Int, b : Int) : Int = a + b
Scalariform is "compatible" with the Scala Style Guide v1.1.0 in the sense that, given the right preference settings, source code that is initially compiliant with the Style Guide will not become uncompliant after formatting. In a number of cases, running the formatter will make uncompliant source more compliant.
| Preference | Value | Default? |
|---|---|---|
| alignParameters | false |
|
| compactStringConcatenation | false |
|
| doubleIndentClassDeclaration | true |
No |
| indentSpaces | 2 |
|
| preserveSpaceBeforeArguments | false |
|
| rewriteArrowSymbols | false |
|
| spaceBeforeColon | false |
As well as global preferences, formatting can be tweaked at the source level through comments.
Disables the formatter for selective portions of a source file:
// format: OFF <-- this directive disables formatting from this point
class AsciiDSL {
n ¦- "1" -+ { n: Node =>
n ¦- "i"
n ¦- "ii"
n ¦- "iii"
n ¦- "iv"
n ¦- "v"
}
n ¦- "2"
n ¦- "3" -+ { n: Node =>
n ¦- "i"
n ¦- "ii" -+ { n: Node =>
n ¦- "a"
n ¦- "b"
n ¦- "c"
}
n ¦- "iii"
n ¦- "iv"
n ¦- "v"
}
// format: ON <-- formatter resumes from this point
...
}
// (see: http://dev.day.com/microsling/content/blogs/main/scalajcr2.html)
Sets a preference for the entire of the source file, overriding the global formatting settings:
// format: +preserveSpaceBeforeArguments
class StackSpec extends FlatSpec with ShouldMatchers {
// ...
stack.pop() should equal (2)
}