Learning Scala

Appendix A. Reserved Words

Table A-1 displays the reserved words in Scala. Reserved words are part of the Scala language definition, and cannot be used as identifiers. To keep the definitions concise, I have used “class” where “class, object, and trait” may be more accurate.

Table A-1. Scala’s reserved words

Name	Description
_	The wildcard operator, representing an expected value.
:	Delimits a value, variable, or function from its type.
@	Defines an annotation for a class or its member. Annotations are a JVM feature but are seldomly used in Scala, with @annotation.tailrec being a popular exception.
#	A type projection, which delimits a type from its subtype.
<-	Delimits a generator from its identifier in a for-loop.
←	A single-character (\u2190) alternative to <-.
<:	The upper-bound operator, restricting types to those that are equal to or extend the given type.
<%	The view-bound operator, allowing any type that may be treated as the given type.
=	The assignment operator.
=>	Used in match expressions and partial functions to indicate a conditional expression, in function types to indicate a return type, and in function literals to define the function body.
⇒	A single-character (\u21D2) alternative to =>.
>:	The lower-bound operator, restricting types to those that are equal to or are extended by the given type.
abstract	Marks a class or trait as being abstract and uninstantiable.
case	Defines a matching pattern in match expressions and partial functions.
catch	Catches an exception. An alternate syntax that predates ...