Symbols used in Syntax of Scala Language

Scala Lang has many different symbols used in its syntax. Below is the list of symbols and its use in Scala language.

• “->” arrow symbol in Scala syntax returns a two element tuple containing the key and value. You can use this symbol as shown in below example-

   Map(1->"Allan", 2->"Bob") (1).->("A) 

• “_” underscore symbol  in scala syntax is intended as a place holder, used in imports, functions literals.

   import com.kodehelp.scala._ case_=> value.toString 

• “:” colon symbol in scala syntax act as separator between identifiers and type annotations.

   def add(i:int):Int= ... 

• “=” equal symbol in scala act as assignment operator

   val ten = 10 

• “=>” symbol is used in function literals to seperate the argument list from the function body

  numbers.filter(x => x)

• “<-” symbol is used for comprehensions in generator expressions

  for(obj <- objects)

• “<:” symbol is called as Upper bound (a subtype of) and is used in parameterized and abstract type declaration to contrain the allowed types.

  def apply[T <: U](x:T)

• “<%” symbolis called as view bound (apply implicit conversion) and is used in paramaterized and abstract type declaration to convert the type using view.

  def m[A<%B](args):R

• “>:” symbolis called lower bound (super type of) and is used in parameterized and abstract type declarations to constrain the allowed types.

  def append[U >:T(x:U)]

• “#” symbolis used to refer to a type declaration nested in another type

  val ic: MyClass#myType

• “@” sybmolmarks an annotation

  @deprecated def sum() = ...