Packages

  • package root

    This is the documentation for the Scala standard library.

    This is the documentation for the Scala standard library.

    Package structure

    The scala package contains core types like Int, Float, Array or Option which are accessible in all Scala compilation units without explicit qualification or imports.

    Notable packages include:

    Other packages exist. See the complete list on the right.

    Additional parts of the standard library are shipped as separate libraries. These include:

    Automatic imports

    Identifiers in the scala package and the scala.Predef object are always in scope by default.

    Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, List is an alias for scala.collection.immutable.List.

    Other aliases refer to classes provided by the underlying platform. For example, on the JVM, String is an alias for java.lang.String.

    Definition Classes
    root
  • package scala

    Core Scala types.

    Core Scala types. They are always available without an explicit import.

    Definition Classes
    root
  • object Predef extends LowPriorityImplicits

    The Predef object provides definitions that are accessible in all Scala compilation units without explicit qualification.

    The Predef object provides definitions that are accessible in all Scala compilation units without explicit qualification.

    Commonly Used Types

    Predef provides type aliases for types which are commonly used, such as the immutable collection types scala.collection.immutable.Map and scala.collection.immutable.Set.

    Console Output

    For basic console output, Predef provides convenience methods print and println, which are aliases of the methods in the object scala.Console.

    Assertions

    A set of assert functions are provided for use as a way to document and dynamically check invariants in code. Invocations of assert can be elided at compile time by providing the command line option -Xdisable-assertions, which raises -Xelide-below above elidable.ASSERTION, to the scalac command.

    Variants of assert intended for use with static analysis tools are also provided: assume, require and ensuring. require and ensuring are intended for use as a means of design-by-contract style specification of pre- and post-conditions on functions, with the intention that these specifications could be consumed by a static analysis tool. For instance,

    def addNaturals(nats: List[Int]): Int = {
      require(nats forall (_ >= 0), "List contains negative numbers")
      nats.foldLeft(0)(_ + _)
    } ensuring(_ >= 0)

    The declaration of addNaturals states that the list of integers passed should only contain natural numbers (i.e. non-negative), and that the result returned will also be natural. require is distinct from assert in that if the condition fails, then the caller of the function is to blame rather than a logical error having been made within addNaturals itself. ensuring is a form of assert that declares the guarantee the function is providing with regards to its return value.

    Implicit Conversions

    A number of commonly applied implicit conversions are also defined here, and in the parent type scala.LowPriorityImplicits. Implicit conversions are provided for the "widening" of numeric values, for instance, converting a Short value to a Long value as required, and to add additional higher-order functions to Array values. These are described in more detail in the documentation of scala.Array.

    Definition Classes
    scala
  • ArrayCharSequence
  • ArrowAssoc
  • Ensuring
  • SeqCharSequence
  • StringFormat
  • any2stringadd
c

scala.Predef

StringFormat

implicit final class StringFormat[A] extends AnyVal

Source
Predef.scala
Linear Supertypes
Type Hierarchy
Ordering
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Inherited
  1. StringFormat
  2. AnyVal
  3. Any
Implicitly
  1. by any2stringadd
  2. by Ensuring
  3. by ArrowAssoc
  4. by any2stringadd
  5. by Ensuring
  6. by ArrowAssoc
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Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new StringFormat(self: A)

Value Members

  1. def getClass(): Class[_ <: AnyVal]

    Returns the runtime class representation of the object.

    Returns the runtime class representation of the object.

    returns

    a class object corresponding to the runtime type of the receiver.

    Definition Classes
    AnyValAny

Deprecated Value Members

  1. def formatted(fmtstr: String): String

    Returns string formatted according to given format string.

    Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

    Annotations
    @deprecated @inline()
    Deprecated

    (Since version 2.12.16) Use formatString.format(value) instead of value.formatted(formatString), or use the f"" string interpolator. In Java 15 and later, formatted resolves to the new method in String which has reversed parameters.