Package io.vavr

Interface CheckedFunction1<T1,​R>

  • Type Parameters:
    T1 - argument 1 of the function
    R - return type of the function
    All Superinterfaces:
    java.io.Serializable
    Functional Interface:
    This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
    @FunctionalInterface
public interface CheckedFunction1<T1,​R>
extends java.io.Serializable
    Represents a function with one argument.

    • Method Summary

      Modifier and Type Method Description
      default <V> CheckedFunction1<T1,​V> andThen​(CheckedFunction1<? super R,​? extends V> after)
      Returns a composed function that first applies this CheckedFunction1 to the given argument and then applies CheckedFunction1 after to the result.
      R apply​(T1 t1)
      Applies this function to one argument and returns the result.
      default int arity()
      Returns the number of function arguments.
      default <V> CheckedFunction1<V,​R> compose​(CheckedFunction1<? super V,​? extends T1> before)
      Returns a composed function that first applies the CheckedFunction1 before the given argument and then applies this CheckedFunction1 to the result.
      static <T1,​R>
      CheckedFunction1<T1,​R>      		 constant​(R value)
      Returns a function that always returns the constant value that you give in parameter.
      default CheckedFunction1<T1,​R> curried()
      Returns a curried version of this function.
      static <T> CheckedFunction1<T,​T> identity()
      Returns the identity CheckedFunction1, i.e.
      default boolean isMemoized()
      Checks if this function is memoizing (= caching) computed values.
      static <T1,​R>
      Function1<T1,​Option<R>>      		 lift​(CheckedFunction1<? super T1,​? extends R> partialFunction)
      Lifts the given partialFunction into a total function that returns an Option result.
      static <T1,​R>
      Function1<T1,​Try<R>>      		 liftTry​(CheckedFunction1<? super T1,​? extends R> partialFunction)
      Lifts the given partialFunction into a total function that returns an Try result.
      default CheckedFunction1<T1,​R> memoized()
      Returns a memoizing version of this function, which computes the return value for given arguments only one time.
      static <T1,​R>
      CheckedFunction1<T1,​R>      		 narrow​(CheckedFunction1<? super T1,​? extends R> f)
      Narrows the given CheckedFunction1<? super T1, ? extends R> to CheckedFunction1<T1, R>
      static <T1,​R>
      CheckedFunction1<T1,​R>      		 of​(CheckedFunction1<T1,​R> methodReference)
      Creates a CheckedFunction1 based on method reference lambda expression Examples (w.l.o.g.
      default Function1<T1,​R> recover​(java.util.function.Function<? super java.lang.Throwable,​? extends java.util.function.Function<? super T1,​? extends R>> recover)
      Return a composed function that first applies this CheckedFunction1 to the given arguments and in case of throwable try to get value from recover function with same arguments and throwable information.
      default CheckedFunction1<T1,​R> reversed()
      Returns a reversed version of this function.
      default CheckedFunction1<Tuple1<T1>,​R> tupled()
      Returns a tupled version of this function.
      default Function1<T1,​R> unchecked()
      Returns an unchecked function that will sneaky throw if an exceptions occurs when applying the function.

    • Method Detail

      • constant

        static <T1,​R> CheckedFunction1<T1,​R> constant​(R value)
        Returns a function that always returns the constant value that you give in parameter.
        Type Parameters:
        T1 - generic parameter type 1 of the resulting function
        R - the result type
        Parameters:
        value - the value to be returned
        Returns:
        a function always returning the given value

      • of

        static <T1,​R> CheckedFunction1<T1,​R> of​(CheckedFunction1<T1,​R> methodReference)
        Creates a CheckedFunction1 based on Examples (w.l.o.g. referring to Function1): 
        // using a lambda expression
 Function1<Integer, Integer> add1 = Function1.of(i -> i + 1);

 // using a method reference (, e.g. Integer method(Integer i) { return i + 1; })
 Function1<Integer, Integer> add2 = Function1.of(this::method);

 // using a lambda reference
 Function1<Integer, Integer> add3 = Function1.of(add1::apply);

        Caution: Reflection loses type information of lambda references. 

        // type of a lambda expression
 Type<?, ?> type1 = add1.getType(); // (Integer) -> Integer

 // type of a method reference
 Type<?, ?> type2 = add2.getType(); // (Integer) -> Integer

 // type of a lambda reference
 Type<?, ?> type3 = add3.getType(); // (Object) -> Object
        Type Parameters:
        R - return type
        T1 - 1st argument
        Parameters:
        methodReference - (typically) a method reference, e.g. Type::method
        Returns:
        a CheckedFunction1

      • lift

        static <T1,​R> Function1<T1,​Option<R>> lift​(CheckedFunction1<? super T1,​? extends R> partialFunction)
        Lifts the given partialFunction into a total function that returns an Option result.
        Type Parameters:
        R - return type
        T1 - 1st argument
        Parameters:
        partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
        Returns:
        a function that applies arguments to the given partialFunction and returns Some(result) if the function is defined for the given arguments, and None otherwise.

      • liftTry

        static <T1,​R> Function1<T1,​Try<R>> liftTry​(CheckedFunction1<? super T1,​? extends R> partialFunction)
        Lifts the given partialFunction into a total function that returns an Try result.
        Type Parameters:
        R - return type
        T1 - 1st argument
        Parameters:
        partialFunction - a function that is not defined for all values of the domain (e.g. by throwing)
        Returns:
        a function that applies arguments to the given partialFunction and returns Success(result) if the function is defined for the given arguments, and Failure(throwable) otherwise.

      • narrow

        static <T1,​R> CheckedFunction1<T1,​R> narrow​(CheckedFunction1<? super T1,​? extends R> f)
        Narrows the given CheckedFunction1<? super T1, ? extends R> to CheckedFunction1<T1, R>
        Type Parameters:
        R - return type
        T1 - 1st argument
        Parameters:
        f - A CheckedFunction1
        Returns:
        the given f instance as narrowed type CheckedFunction1<T1, R>

      • identity

        static <T> CheckedFunction1<T,​T> identity()
        Returns the identity CheckedFunction1, i.e. the function that returns its input.
        Type Parameters:
        T - argument type (and return type) of the identity function
        Returns:
        the identity CheckedFunction1

      • apply

        R apply​(T1 t1)
 throws java.lang.Throwable
        Applies this function to one argument and returns the result.
        Parameters:
        t1 - argument 1
        Returns:
        the result of function application
        Throws:
        java.lang.Throwable - if something goes wrong applying this function to the given arguments

      • arity

        default int arity()
        Returns the number of function arguments.
        Returns:
        an int value >= 0
        See Also:
        Arity

      • curried

        default CheckedFunction1<T1,​R> curried()
        Returns a curried version of this function.
        Returns:
        a curried function equivalent to this.

      • tupled

        default CheckedFunction1<Tuple1<T1>,​R> tupled()
        Returns a tupled version of this function.
        Returns:
        a tupled function equivalent to this.

      • reversed

        default CheckedFunction1<T1,​R> reversed()
        Returns a reversed version of this function. This may be useful in a recursive context.
        Returns:
        a reversed function equivalent to this.

      • memoized

        default CheckedFunction1<T1,​R> memoized()
        Returns a memoizing version of this function, which computes the return value for given arguments only one time. On subsequent calls given the same arguments the memoized value is returned.

        Please note that memoizing functions do not permit null as single argument or return value.

        Returns:
        a memoizing function equivalent to this.

      • isMemoized

        default boolean isMemoized()
        Checks if this function is memoizing (= caching) computed values.
        Returns:
        true, if this function is memoizing, false otherwise

      • recover

        default Function1<T1,​R> recover​(java.util.function.Function<? super java.lang.Throwable,​? extends java.util.function.Function<? super T1,​? extends R>> recover)
        Return a composed function that first applies this CheckedFunction1 to the given arguments and in case of throwable try to get value from recover function with same arguments and throwable information.
        Parameters:
        recover - the function applied in case of throwable
        Returns:
        a function composed of this and recover
        Throws:
        java.lang.NullPointerException - if recover is null

      • unchecked

        default Function1<T1,​R> unchecked()
        Returns an unchecked function that will sneaky throw if an exceptions occurs when applying the function.
        Returns:
        a new Function1 that throws a Throwable.

      • andThen

        default <V> CheckedFunction1<T1,​V> andThen​(CheckedFunction1<? super R,​? extends V> after)
        Returns a composed function that first applies this CheckedFunction1 to the given argument and then applies CheckedFunction1 after to the result.
        Type Parameters:
        V - return type of after
        Parameters:
        after - the function applied after this
        Returns:
        a function composed of this and after
        Throws:
        java.lang.NullPointerException - if after is null

      • compose

        default <V> CheckedFunction1<V,​R> compose​(CheckedFunction1<? super V,​? extends T1> before)
        Returns a composed function that first applies the CheckedFunction1 before the given argument and then applies this CheckedFunction1 to the result.
        Type Parameters:
        V - argument type of before
        Parameters:
        before - the function applied before this
        Returns:
        a function composed of before and this
        Throws:
        java.lang.NullPointerException - if before is null