Class NonEmptyList<A>

java.lang.Object
fj.data.NonEmptyList<A>
All Implemented Interfaces:
Iterable<A>
public final class NonEmptyList<A> extends Object implements Iterable<A>
Provides an in-memory, immutable, singly linked list with total head and tail.

  • Field Details

    • tail

      private final List<A> tail

  • Constructor Details

    • NonEmptyList

      private NonEmptyList(A head, List<A> tail)

  • Method Details

    • iterator

      public Iterator<A> iterator()
      Returns an iterator for this non-empty list. This method exists to permit the use in a for-each loop.
      Specified by:
      iterator in interface Iterable<A>
      Returns:
      A iterator for this non-empty list.

    • head

      public A head()
      The first element of this linked list.

    • tail

      public List<A> tail()
      This list without the first element.

    • cons

      public NonEmptyList<A> cons(A a)
      Prepend the given value to this list.
      Parameters:
      a - The value to prepend.
      Returns:
      A non-empty list with an extra element.

    • snoc

      public NonEmptyList<A> snoc(A a)
      Appends (snoc) the given element to this non empty list to produce a new non empty list. O(n).
      Parameters:
      a - The element to append to this non empty list.
      Returns:
      A new non empty list with the given element appended.

    • length

      public int length()
      The length of this list.
      Returns:
      The length of this list.

    • append

      public NonEmptyList<A> append(List<A> as)
      Appends the given list to this list.
      Parameters:
      as - The list to append.
      Returns:
      A new list with the given list appended.

    • append

      public NonEmptyList<A> append(NonEmptyList<A> as)
      Appends the given list to this list.
      Parameters:
      as - The list to append.
      Returns:
      A new list with the given list appended.

    • foldRight1

      public final A foldRight1(F<A,F<A,A>> f)
      Performs a right-fold reduction across this list. This function uses O(length) stack space.

    • foldRight1

      public final A foldRight1(F2<A,A,A> f)
      Performs a right-fold reduction across this list. This function uses O(length) stack space.

    • foldLeft1

      public final A foldLeft1(F<A,F<A,A>> f)
      Performs a left-fold reduction across this list. This function runs in constant space.

    • foldLeft1

      public final A foldLeft1(F2<A,A,A> f)
      Performs a left-fold reduction across this list. This function runs in constant space.

    • map

      public <B> NonEmptyList<B> map(F<A,B> f)
      Maps the given function across this list.
      Parameters:
      f - The function to map across this list.
      Returns:
      A new list after the given function has been applied to each element.

    • bind

      public <B> NonEmptyList<B> bind(F<A, NonEmptyList<B>> f)
      Binds the given function across each element of this list with a final join.
      Parameters:
      f - The function to apply to each element of this list.
      Returns:
      A new list after performing the map, then final join.

    • sublists

      public NonEmptyList<NonEmptyList<A>> sublists()
      Returns a NonEmptyList of the sublists of this list.
      Returns:
      a NonEmptyList of the sublists of this list.

    • tails

      public NonEmptyList<NonEmptyList<A>> tails()
      Returns a NonEmptyList of the tails of this list. A list is considered a tail of itself for the purpose of this function (Comonad pattern).
      Returns:
      A NonEmptyList of the tails of this list.

    • mapTails

      public <B> NonEmptyList<B> mapTails(F<NonEmptyList<A>, B> f)
      Maps the given function across the tails of this list (comonad pattern).
      Parameters:
      f - The function to map across the tails of this list.
      Returns:
      The results of applying the given function to the tails of this list, as a NonEmptyList.

    • intersperse

      public NonEmptyList<A> intersperse(A a)
      Intersperses the given argument between each element of this non empty list.
      Parameters:
      a - The separator to intersperse in this non empty list.
      Returns:
      A non empty list with the given separator interspersed.

    • reverse

      public NonEmptyList<A> reverse()
      Reverse this non empty list in constant stack space.
      Returns:
      A new non empty list with the elements in reverse order.

    • sort

      public NonEmptyList<A> sort(Ord<A> o)
      Sorts this non empty list using the given order over elements using a merge sort algorithm.
      Parameters:
      o - The order over the elements of this non empty list.
      Returns:
      A sorted non empty list according to the given order.

    • minimum

      public final A minimum(Ord<A> o)
      Returns the minimum element in this non empty list according to the given ordering.
      Parameters:
      o - An ordering for the elements of this non empty list.
      Returns:
      The minimum element in this list according to the given ordering.

    • maximum

      public final A maximum(Ord<A> o)
      Returns the maximum element in this non empty list according to the given ordering.
      Parameters:
      o - An ordering for the elements of this non empty list.
      Returns:
      The maximum element in this list according to the given ordering.

    • zip

      public <B> NonEmptyList<P2<A,B>> zip(NonEmptyList<B> bs)
      Zips this non empty list with the given non empty list to produce a list of pairs. If this list and the given list have different lengths, then the longer list is normalised so this function never fails.
      Parameters:
      bs - The non empty list to zip this non empty list with.
      Returns:
      A new non empty list with a length the same as the shortest of this list and the given list.

    • zipIndex

      public NonEmptyList<P2<A,Integer>> zipIndex()
      Zips this non empty list with the index of its element as a pair.
      Returns:
      A new non empty list with the same length as this list.

    • zipWith

      public <B,C> NonEmptyList<C> zipWith(List<B> bs, F<A,F<B,C>> f)
      Zips this non empty list with the given non empty list using the given function to produce a new list. If this list and the given list have different lengths, then the longer list is normalised so this function never fails.
      Parameters:
      bs - The non empty list to zip this non empty list with.
      f - The function to zip this non empty list and the given non empty list with.
      Returns:
      A new non empty list with a length the same as the shortest of this list and the given list.

    • zipWith

      public <B,C> NonEmptyList<C> zipWith(List<B> bs, F2<A,B,C> f)
      Zips this non empty list with the given non empty list using the given function to produce a new list. If this list and the given list have different lengths, then the longer list is normalised so this function never fails.
      Parameters:
      bs - The non empty list to zip this non empty list with.
      f - The function to zip this non empty list and the given non empty list with.
      Returns:
      A new non empty list with a length the same as the shortest of this list and the given list.

    • unzip

      public static <A,B> P2<NonEmptyList<A>, NonEmptyList<B>> unzip(NonEmptyList<P2<A,B>> xs)
      Transforms a non empty list of pairs into a non empty list of first components and a non empty list of second components.
      Parameters:
      xs - The non empty list of pairs to transform.
      Returns:
      A non empty list of first components and a non empty list of second components.

    • toList

      public List<A> toList()
      Returns a List projection of this list.
      Returns:
      A List projection of this list.

    • toCollection

      public Collection<A> toCollection()
      Projects an immutable collection of this non-empty list.
      Returns:
      An immutable collection of this non-empty list.

    • toList_

      public static <A> F<NonEmptyList<A>, List<A>> toList_()
      Returns a function that takes a non-empty list to a list.
      Returns:
      A function that takes a non-empty list to a list.

    • nel

      public static <A> NonEmptyList<A> nel(A head, List<A> tail)
      Return a non-empty list with the given head and tail.
      Parameters:
      head - The first element of the new list.
      tail - The remaining elements of the new list.
      Returns:
      A non-empty list with the given head and tail.

    • nel

      @SafeVarargs public static <A> NonEmptyList<A> nel(A head, A... tail)
      Constructs a non empty list from the given elements.
      Parameters:
      head - The first in the non-empty list.
      tail - The elements to construct a list's tail with.
      Returns:
      A non-empty list with the given elements.

    • nel

      public static <A> F<A, NonEmptyList<A>> nel()
      Returns a function that puts an element into a non-empty list.
      Returns:
      A function that puts an element into a non-empty list.

    • fromList

      public static <A> Option<NonEmptyList<A>> fromList(List<A> as)
      Returns a potential non-empty list from the given list. A non-value is returned if the given list is empty.
      Parameters:
      as - The list to construct a potential non-empty list with.
      Returns:
      A potential non-empty list from the given list.

    • join

      public static <A> NonEmptyList<A> join(NonEmptyList<NonEmptyList<A>> o)
      Concatenate (join) a non empty list of non empty lists.
      Parameters:
      o - The non empty list of non empty lists to join.
      Returns:
      A new non empty list that is the concatenation of the given lists.

    • equals

      public boolean equals(Object obj)
      Perform an equality test on this list which delegates to the .equals() method of the member instances. This is implemented with Equal.nonEmptyListEqual using the anyEqual rule.
      Overrides:
      equals in class Object
      Parameters:
      obj - the other object to check for equality against.
      Returns:
      true if this list is equal to the provided argument

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object