Class Enumerator<A>

java.lang.Object
fj.data.Enumerator<A>
public final class Enumerator<A> extends Object
Abstracts over a type that may have a successor and/or predecessor value. This implies ordering for that type. A user may construct an enumerator with an optimised version for plus, otherwise a default is implemented using the given successor/predecessor implementations.

For any enumerator e, the following laws must satisfy:

  • forall a. e.successor(a).forall(\t -> e.predecessor(t).forall(\z -> z == a))
  • forall a. e.predecessor(a).forall(\t -> e.successor(t).forall(\z -> z == a))
  • e.max().forall(\t -> e.successor(t).isNone)
  • e.min().forall(\t -> e.predecessor(t).isNone)
  • forall a n. e.plus(a, 0) == Some(a)
  • forall a n | n > 0. e.plus(a, n) == e.plus(a, n - 1)
  • forall a n | n < 0. e.plus(a, n) == e.plus(a, n + 1)
Version:
%build.number%

  • Field Details

    • successor

      private final F<A, Option<A>> successor

    • predecessor

      private final F<A, Option<A>> predecessor

    • max

      private final Option<A> max

    • min

      private final Option<A> min

    • order

      private final Ord<A> order

    • plus

      private final F<A, F<Long, Option<A>>> plus

    • booleanEnumerator

      public static final Enumerator<Boolean> booleanEnumerator
      An enumerator for boolean.

    • byteEnumerator

      public static final Enumerator<Byte> byteEnumerator
      An enumerator for byte.

    • charEnumerator

      public static final Enumerator<Character> charEnumerator
      An enumerator for char.

    • doubleEnumerator

      public static final Enumerator<Double> doubleEnumerator
      An enumerator for double.

    • floatEnumerator

      public static final Enumerator<Float> floatEnumerator
      An enumerator for float.

    • intEnumerator

      public static final Enumerator<Integer> intEnumerator
      An enumerator for int.

    • bigintEnumerator

      public static final Enumerator<BigInteger> bigintEnumerator
      An enumerator for BigInteger.

    • bigdecimalEnumerator

      public static final Enumerator<BigDecimal> bigdecimalEnumerator
      An enumerator for BigDecimal.

    • longEnumerator

      public static final Enumerator<Long> longEnumerator
      An enumerator for long.

    • shortEnumerator

      public static final Enumerator<Short> shortEnumerator
      An enumerator for short.

    • orderingEnumerator

      public static final Enumerator<Ordering> orderingEnumerator
      An enumerator for Ordering.

    • naturalEnumerator

      public static final Enumerator<Natural> naturalEnumerator
      An enumerator for Natural

  • Constructor Details

  • Method Details

    • successor

      public F<A, Option<A>> successor()
      Returns the potential successor of a value for this enumerator in curried form.
      Returns:
      The potential successor of a value for this enumerator in curried form.

    • successor

      public Option<A> successor(A a)
      Returns the potential successor of a value for this enumerator.
      Parameters:
      a - The value to return the successor of.
      Returns:
      The potential successor of a value for this enumerator.

    • predecessor

      public F<A, Option<A>> predecessor()
      Returns the potential predecessor of a value for this enumerator in curried form.
      Returns:
      The potential predecessor of a value for this enumerator in curried form.

    • predecessor

      public Option<A> predecessor(A a)
      Returns the potential predecessor of a value for this enumerator.
      Parameters:
      a - The value to return the predecessor of.
      Returns:
      The potential predecessor of a value for this enumerator.

    • max

      public Option<A> max()
      Returns the maximum value for this enumerator if there is one.
      Returns:
      The maximum value for this enumerator if there is one.

    • min

      public Option<A> min()
      Returns the minimum value for this enumerator if there is one.
      Returns:
      The minimum value for this enumerator if there is one.

    • plus

      public F<A, F<Long, Option<A>>> plus()
      Returns a function that moves a value along the enumerator a given number of times.
      Returns:
      A function that moves a value along the enumerator a given number of times.

    • plus

      public F<Long, Option<A>> plus(A a)
      Returns a function that moves a value along the enumerator a given number of times.
      Parameters:
      a - The value to begin moving along from.
      Returns:
      A function that moves a value along the enumerator a given number of times.

    • plus

      public F<A, Option<A>> plus(long l)
      Returns a function that moves a value along the enumerator a given number of times.
      Parameters:
      l - The number of times to move along the enumerator.
      Returns:
      A function that moves a value along the enumerator a given number of times.

    • plus

      public Option<A> plus(A a, long l)
      Moves a value along the enumerator a given number of times.
      Parameters:
      a - The value to begin moving along from.
      l - The number of times to move along the enumerator.
      Returns:
      A potential value after having moved the given number of times.

    • order

      public Ord<A> order()
      Returns the ordering for the enumerator.
      Returns:
      The ordering for the enumerator.

    • xmap

      public <B> Enumerator<B> xmap(F<A,B> f, F<B,A> g)
      Invariant functor map over this enumerator.
      Parameters:
      f - The covariant map.
      g - The contra-variant map.
      Returns:
      An enumerator after the given functions are applied.

    • toStream

      public Stream<A> toStream(A a)
      Returns a stream of the values from this enumerator, starting at the given value, counting up.
      Parameters:
      a - A value at which to begin the stream.
      Returns:
      a stream of the values from this enumerator, starting at the given value, counting up.

    • toStream

      public Stream<A> toStream(Bounded<A> bounded)
      Returns a stream of the values from this enumerator, starting at the min of given Bounded, ending at the max, counting up.
      Parameters:
      bounded - A value at which to begin the stream.
      Returns:
      a stream of the values from this enumerator, cut by bounded, counting up.

    • setMin

      public Enumerator<A> setMin(Option<A> min)
      Create a new enumerator with the given minimum value.
      Parameters:
      min - A minimum value.
      Returns:
      A new enumerator identical to this one, but with the given minimum value.

    • setMax

      public Enumerator<A> setMax(Option<A> max)
      Create a new enumerator with the given maximum value.
      Parameters:
      max - A maximum value.
      Returns:
      A new enumerator identical to this one, but with the given maximum value.

    • enumerator

      public static <A> Enumerator<A> enumerator(F<A, Option<A>> successor, F<A, Option<A>> predecessor, Option<A> max, Option<A> min, Ord<A> order, F<A, F<Long, Option<A>>> plus)
      Construct an enumerator. `
      Parameters:
      successor - The successor function.
      predecessor - The predecessor function.
      max - The potential maximum value.
      min - The potential minimum value.
      order - The ordering for the type.
      plus - The function to move the enumeration a given number of times. This may be supplied for a performance enhancement for certain types.
      Returns:
      An enumerator with the given values.

    • enumerator

      public static <A> Enumerator<A> enumerator(F<A, Option<A>> successor, F<A, Option<A>> predecessor, Option<A> max, Option<A> min, Ord<A> order)
      Construct an enumerator. The plus function is derived from the successor and predecessor.
      Parameters:
      successor - The successor function.
      predecessor - The predecessor function.
      max - The potential maximum value.
      min - The potential minimum value.
      order - The ordering for the type.
      Returns:
      An enumerator with the given values.