Indentation
Indentation should follow the “2-space convention”. Thus, instead of indenting like this:
1.
// wrong!
2.
class Foo {
def bar = ...
3.
4.
}
You should indent like this:
1.
// right!
2.
class Foo {
def bar = ..
3.
4.
}
The Scala language encourages a startling amount of nested scopes and logical blocks (function values and such).
Do yourself a favor and don’t penalize yourself syntactically for opening up a new block. Coming from Java, this
style does take a bit of getting used to, but it is well worth the effort.
Line Wrapping
There are times when a single expression reaches a length where it becomes unreadable to keep it confined to a
single line (usually that length is anywhere above 80 characters). In such cases, thepreferred approach is to simply
split the expression up into multiple expressions by assigning intermediate results to values. However, this is not
always a practical solution.
When it is absolutely necessary to wrap an expression across more than one line, each successive line should be
indented two spaces from the first. Also remember that Scala requires each “wrap line” to either have an unclosed
parenthetical or to end with an infix method in which the right parameter is not given:
1.
val result = 1 + 2 + 3 + 4 + 5 + 6 +
2.
7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 +
3.
15 + 16 + 17 + 18 + 19 + 20
Without this trailing method, Scala will infer a semi-colon at the end of a line which was intended to wrap, throwing
off the compilation sometimes without even so much as a warning.
Methods with Numerous Arguments
When calling a method which takes numerous arguments (in the range of five or more), it is often necessary to wrap
the method invocation onto multiple lines. In such cases, put all arguments on a line by themselves, indented two
spaces from the current indent level:
1.
foo(
2.
someVeryLongFieldName,
3.
andAnotherVeryLongFieldName,
4....