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NonEmptyIList<A> final ​

final class NonEmptyIList<A> with RIterableOnce<A>, RIterable<A>, RSeq<A>

Annotations: @immutable

An immutable IList that contains at least one element.

Mixed-in types

Available Extensions

Constructors ​

NonEmptyIList() const ​

const NonEmptyIList(A head, [IList<A> _tail = const Nil()])

Creates a list with the given head and tail.

Implementation
dart
const NonEmptyIList(this.head, [this._tail = const Nil()]);

Properties ​

hashCode no setter override ​

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Implementation
dart
@override
int get hashCode => MurmurHash3.listHash(toIList());

head final ​

final A head

Returns the first element of this collection, or throws if it is empty.

Implementation
dart
@override
final A head;

headOption no setter inherited ​

Option<A> get headOption

Returns the first element of this collection as a Some if non-empty. If this collction is empty, None is returned.

Inherited from RIterable.

Implementation
dart
Option<A> get headOption {
  final it = iterator;
  return Option.when(() => it.hasNext, () => it.next());
}

init no setter override ​

IList<A> get init

Returns all elements from this collection except the last. If this collection is empty, an empty collection is returned.

Implementation
dart
@override
IList<A> get init => toIList().init;

inits no setter override ​

RIterator<IList<A>> get inits

Returns an iterator of all potential tails of this collection, starting with the entire collection and ending with an empty one.

Implementation
dart
@override
RIterator<IList<A>> get inits => toIList().inits;

isEmpty no setter override ​

bool get isEmpty

Whether this collection contains no elements.

Implementation
dart
@override
bool get isEmpty => false;

isNotEmpty no setter inherited ​

bool get isNotEmpty

Whether this collection contains at least one element.

Inherited from RIterableOnce.

Implementation
dart
bool get isNotEmpty => !isEmpty;

isTraversableAgain no setter inherited ​

bool get isTraversableAgain

Whether this collection can be traversed more than once.

Always false for a bare RIterableOnce; overridden to true by RIterable and its subtypes.

Inherited from RIterableOnce.

Implementation
dart
bool get isTraversableAgain => false;

iterator no setter override ​

RIterator<A> get iterator

Returns an RIterator over the elements of this collection.

Implementation
dart
@override
RIterator<A> get iterator => RIterator.single(head).concat(_tail.iterator);

knownSize no setter inherited ​

int get knownSize

Returns the number of elements in this collection, if that number is already known. If not, -1 is returned.

Inherited from RIterableOnce.

Implementation
dart
int get knownSize => -1;

last no setter inherited ​

A get last

Returns the last element of this collection, or throws if it is empty.

Inherited from RIterable.

Implementation
dart
A get last {
  final it = iterator;
  var lst = it.next();

  while (it.hasNext) {
    lst = it.next();
  }

  return lst;
}

lastOption no setter inherited ​

Option<A> get lastOption

Returns the last element of this collection as a Some, or None if this collection is empty.

Inherited from RIterable.

Implementation
dart
Option<A> get lastOption {
  if (isEmpty) {
    return none();
  } else {
    final it = iterator;
    var last = it.next();

    while (it.hasNext) {
      last = it.next();
    }

    return Some(last);
  }
}

length no setter override ​

int get length

The number of elements in this sequence.

Implementation
dart
@override
int get length => 1 + _tail.length;

nonEmpty no setter inherited ​

bool get nonEmpty

Whether this collection contains at least one element.

Inherited from RIterableOnce.

Implementation
dart
bool get nonEmpty => !isEmpty;

runtimeType no setter inherited ​

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation
dart
external Type get runtimeType;

size no setter inherited ​

int get size

Returns the number of elements in this collection.

Inherited from RSeq.

Implementation
dart
@override
int get size => length;

tail no setter override ​

IList<A> get tail

Returns a new collection with the first element removed. If this collection is empty, an empty collection is returned.

Implementation
dart
@override
IList<A> get tail => _tail;

tails no setter override ​

RIterator<IList<A>> get tails

Returns an iterator of all potential tails of this collection, starting with the entire collection and ending with an empty one.

Implementation
dart
@override
RIterator<IList<A>> get tails => toIList().tails;

Methods ​

appended() override ​

NonEmptyIList<A> appended(A elem)

Returns a new Seq, with the given elem added to the end.

Implementation
dart
@override
NonEmptyIList<A> appended(A elem) => NonEmptyIList(head, _tail.appended(elem));

appendedAll() override ​

NonEmptyIList<A> appendedAll(RIterableOnce<A> suffix)

Returns a new Seq, with elems added to the end.

Implementation
dart
@override
NonEmptyIList<A> appendedAll(RIterableOnce<A> suffix) =>
    NonEmptyIList(head, _tail.appendedAll(suffix));

canEqual() inherited ​

bool canEqual(Object other)

Inherited from RSeq.

Implementation
dart
bool canEqual(Object other) => true;

collect() override ​

IList<B> collect<B>(Option<B> Function(A) f)

Returns a new collection by applying f to each element an only keeping results of type Some.

Implementation
dart
@override
IList<B> collect<B>(Function1<A, Option<B>> f) => toIList().collect(f);

collectFirst() inherited ​

Option<B> collectFirst<B>(Option<B> Function(A) f)

Applies f to each element of this collection, returning the first element that results in a Some, if any.

Inherited from RIterableOnce.

Implementation
dart
Option<B> collectFirst<B>(Function1<A, Option<B>> f) {
  final it = iterator;

  while (it.hasNext) {
    final x = f(it.next());
    if (x.isDefined) return x;
  }

  return none();
}

combinations() override ​

RIterator<IList<A>> combinations(int n)

Returns an Iterator that will produce all combinations of elements from this sequence of size n in order.

Given the list [1, 2, 2, 2], combinations of size 2 would result in [1, 2] and [2, 2]. Note that [2, 1] would not be included since combinations are taken from element in order.

Also note from the example above, [1, 2] would only be included once even though there are technically 3 ways to generate a combination of [1, 2], only one will be included in the result since the other 2 are duplicates.

Implementation
dart
@override
RIterator<IList<A>> combinations(int n) => toIList().combinations(n);

concat() override ​

NonEmptyIList<A> concat(RIterableOnce<A> suffix)

Returns a copy of this collection, with elems added to the end.

Implementation
dart
@override
NonEmptyIList<A> concat(RIterableOnce<A> suffix) => NonEmptyIList(head, _tail.concat(suffix));

concatNel() ​

NonEmptyIList<A> concatNel(NonEmptyIList<A> nel)

Adds all elements of nel to the end of this list.

dart
final l = nel(1, [2, 3, 4, 5]);
assert(l.concatNel(l) == nel(1, [2, 3, 4, 5, 1, 2, 3, 4, 5]));
Implementation
dart
NonEmptyIList<A> concatNel(NonEmptyIList<A> nel) => NonEmptyIList(head, _tail.concat(nel));

contains() inherited ​

bool contains(A elem)

Returns true, if any element of this collection equals elem.

Inherited from RSeq.

Implementation
dart
bool contains(A elem) => exists((a) => a == elem);

containsSlice() inherited ​

bool containsSlice(RSeq<A> that)

Returns true if that is contained in this collection, in order.

Inherited from RSeq.

Implementation
dart
bool containsSlice(RSeq<A> that) => indexOfSlice(that).isDefined;

copyToArray() inherited ​

int copyToArray(Array<A> xs, [int start = 0, int? n])

Copies elements into xs starting at start, writing at most n elements (or all remaining capacity when n is omitted).

Returns the number of elements actually copied.

Inherited from RIterableOnce.

Implementation
dart
int copyToArray(Array<A> xs, [int start = 0, int? n]) {
  final it = iterator;
  final end = start + min(n ?? Integer.maxValue, xs.length - start);
  var i = start;

  while (i < end && it.hasNext) {
    xs[i] = it.next();
    i += 1;
  }

  return i - start;
}

corresponds() inherited ​

bool corresponds<B>(RSeq<B> that, bool Function(A, B) p)

Returns true if this collection has the same size as that and each corresponding element from this and that satisfies the given predicate p.

Inherited from RSeq.

Implementation
dart
@override
bool corresponds<B>(RSeq<B> that, Function2<A, B, bool> p) {
  final i = iterator;
  final j = that.iterator;

  while (i.hasNext && j.hasNext) {
    if (!p(i.next(), j.next())) return false;
  }

  return !i.hasNext && !j.hasNext;
}

count() inherited ​

int count(bool Function(A) p)

Return the number of elements in this collection that satisfy the given predicate.

Inherited from RIterableOnce.

Implementation
dart
int count(Function1<A, bool> p) {
  var res = 0;
  final it = iterator;

  while (it.hasNext) {
    if (p(it.next())) res += 1;
  }

  return res;
}

diff() override ​

IList<A> diff(RSeq<A> that)

Returns a new collection with the difference of this and that, i.e. all elements that appear in only this collection.

Implementation
dart
@override
IList<A> diff(RSeq<A> that) => toIList().diff(that);

distinct() override ​

NonEmptyIList<A> distinct()

Returns a new collection where every element is distinct according to equality.

Implementation
dart
@override
NonEmptyIList<A> distinct() => NonEmptyIList.unsafe(toIList().distinct());

distinctBy() override ​

NonEmptyIList<A> distinctBy<B>(B Function(A) f)

Returns a new collection where every element is distinct according to the application of f to each element.

Implementation
dart
@override
NonEmptyIList<A> distinctBy<B>(Function1<A, B> f) =>
    NonEmptyIList.unsafe(toIList().distinctBy(f));

drop() override ​

IList<A> drop(int n)

Returns a new collection with the first n elements removed.

Implementation
dart
@override
IList<A> drop(int n) => toIList().drop(n);

dropRight() override ​

IList<A> dropRight(int n)

Return a new collection with the last n elements removed.

Implementation
dart
@override
IList<A> dropRight(int n) => toIList().dropRight(n);

dropWhile() override ​

IList<A> dropWhile(bool Function(A) p)

Returns a new collection with leading elements satisfying p removed.

Implementation
dart
@override
IList<A> dropWhile(Function1<A, bool> p) => toIList().dropWhile(p);

endsWith() inherited ​

bool endsWith(RIterable<A> that)

Returns true if the end of this collection has the same elements in order as that. Otherwise, false is returned.

Inherited from RSeq.

Implementation
dart
bool endsWith(RIterable<A> that) {
  if (that.isEmpty) {
    return true;
  } else {
    final i = iterator.drop(length - that.size);
    final j = that.iterator;
    while (i.hasNext && j.hasNext) {
      if (i.next() != j.next()) return false;
    }

    return !j.hasNext;
  }
}

exists() inherited ​

bool exists(bool Function(A) p)

Returns true if any element of this collection satisfies the given predicate, false if no elements satisfy it.

Inherited from RIterableOnce.

Implementation
dart
bool exists(Function1<A, bool> p) {
  var res = false;
  final it = iterator;

  while (!res && it.hasNext) {
    res = p(it.next());
  }

  return res;
}

filter() override ​

IList<A> filter(bool Function(A) p)

Returns a new collection containing only elements that satisfy p.

Implementation
dart
@override
IList<A> filter(Function1<A, bool> p) => toIList().filter(p);

filterNot() override ​

IList<A> filterNot(bool Function(A) p)

Returns a new collection containing only elements that do not satisfy p.

Implementation
dart
@override
IList<A> filterNot(Function1<A, bool> p) => toIList().filterNot(p);

find() inherited ​

Option<A> find(bool Function(A) p)

Returns the first element from this collection that satisfies the given predicate p. If no element satisfies p, None is returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> find(Function1<A, bool> p) {
  final it = iterator;

  while (it.hasNext) {
    final a = it.next();
    if (p(a)) return Some(a);
  }

  return none();
}

findLast() inherited ​

Option<A> findLast(bool Function(A) p)

Returns the last element satisfying p as Some, or None if none.

Inherited from RSeq.

Implementation
dart
Option<A> findLast(Function1<A, bool> p) {
  final it = reverseIterator();
  while (it.hasNext) {
    final elem = it.next();
    if (p(elem)) return Some(elem);
  }

  return none();
}

flatMap() override ​

NonEmptyIList<B> flatMap<B>(NonEmptyIList<B> Function(A) f)

Returns a new collection by applying f to each element and concatenating the results.

Implementation
dart
@override
NonEmptyIList<B> flatMap<B>(Function1<A, NonEmptyIList<B>> f) =>
    f(head).concat(_tail.flatMap((a) => f(a).toIList()));

fold() inherited ​

A fold(A init, A Function(A, A) op)

Alias for foldLeft with a same-type accumulator.

Inherited from RIterable.

Implementation
dart
A fold(A init, Function2<A, A, A> op) => foldLeft(init, op);

foldLeft() inherited ​

B foldLeft<B>(B z, B Function(B, A) op)

Returns a summary value by applying op to all elements of this collection, moving from left to right. The fold uses a seed value of z.

Inherited from RIterableOnce.

Implementation
dart
B foldLeft<B>(B z, Function2<B, A, B> op) {
  var result = z;
  final it = iterator;

  while (it.hasNext) {
    result = op(result, it.next());
  }

  return result;
}

foldRight() inherited ​

B foldRight<B>(B z, B Function(A, B) op)

Returns a summary value by applying op to all elements of this collection, moving from right to left. The fold uses a seed value of z.

Inherited from RIterableOnce.

Implementation
dart
B foldRight<B>(B z, Function2<A, B, B> op) => _reversed().foldLeft(z, (b, a) => op(a, b));

forall() inherited ​

bool forall(bool Function(A) p)

Returns true if all elements of this collection satisfy the given predicate, false if any elements do not.

Inherited from RIterableOnce.

Implementation
dart
bool forall(Function1<A, bool> p) {
  var res = true;
  final it = iterator;

  while (res && it.hasNext) {
    res = p(it.next());
  }

  return res;
}

foreach() inherited ​

void foreach<U>(U Function(A) f)

Applies f to each element of this collection, discarding any resulting values.

Inherited from RIterableOnce.

Implementation
dart
void foreach<U>(Function1<A, U> f) {
  final it = iterator;
  while (it.hasNext) {
    f(it.next());
  }
}

groupBy() override ​

IMap<K, NonEmptyIList<A>> groupBy<K>(K Function(A) f)

Partitions all elements of this collection by applying f to each element and accumulating duplicate keys in the returned IMap.

Implementation
dart
@override
IMap<K, NonEmptyIList<A>> groupBy<K>(Function1<A, K> f) => groupMap(f, identity);

grouped() override ​

RIterator<IList<A>> grouped(int size)

Returns a new iterator where each element is a collection of size elements from the original collection. The last element may contain less than size elements.

Implementation
dart
@override
RIterator<IList<A>> grouped(int size) => toIList().grouped(size);

groupMap() override ​

IMap<K, NonEmptyIList<V>> groupMap<K, V>(K Function(A) key, V Function(A) f)

Creates a new map by generating a key-value pair for each elements of this collection using key and f. Any elements that generate the same key will have the resulting values accumulated in the returned map.

Implementation
dart
@override
IMap<K, NonEmptyIList<V>> groupMap<K, V>(
  Function1<A, K> key,
  Function1<A, V> f,
) => foldLeft(
  imap({}),
  (acc, a) => acc.updatedWith(
    key(a),
    (prev) => prev.map((l) => l.appended(f(a))).orElse(() => nel(f(a)).some),
  ),
);

groupMapReduce() inherited ​

IMap<K, B> groupMapReduce<K, B>(
  K Function(A) key,
  B Function(A) f,
  B Function(B, B) reduce,
)

Partitions all elements of this collection by applying key to each element. Additionally f is applied to each element to generate a value. If multiple values are generating for the same key, those values will be combined using reduce.

Inherited from RIterable.

Implementation
dart
IMap<K, B> groupMapReduce<K, B>(
  Function1<A, K> key,
  Function1<A, B> f,
  Function2<B, B, B> reduce,
) {
  final m = <K, B>{};

  foreach((elem) {
    m.update(key(elem), (b) => reduce(b, f(elem)), ifAbsent: () => f(elem));
  });

  return IMap.fromDart(m);
}

indexOf() inherited ​

Option<int> indexOf(A elem, [int from = 0])

Returns the first index, if any, where the element at that index equals elem. If no index contains elem, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> indexOf(A elem, [int from = 0]) => indexWhere((a) => a == elem, from);

indexOfSlice() inherited ​

Option<int> indexOfSlice(RSeq<A> that, [int from = 0])

Finds the first index in this collection where the next sequence of elements is equal to that. If that cannot be found in this collection, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> indexOfSlice(RSeq<A> that, [int from = 0]) {
  if (that.isEmpty && from == 0) {
    return const Some(0);
  } else {
    final l = knownSize;
    final tl = that.knownSize;

    if (l >= 0 && tl >= 0) {
      final clippedFrom = max(0, from);
      if (from > l) {
        return none();
      } else if (tl < 1) {
        return Some(clippedFrom);
      } else if (l < tl) {
        return none();
      } else {
        return _kmpSearch(this, clippedFrom, l, that, 0, tl, true);
      }
    } else {
      var i = from;
      var s = drop(i);
      while (s.nonEmpty) {
        if (s.startsWith(that)) return Some(i);

        i += 1;
        s = s.tail;
      }
      return none();
    }
  }
}

indexWhere() inherited ​

Option<int> indexWhere(bool Function(A) p, [int from = 0])

Returns the index of the first element that satisfies the predicate p. If no element satisfies, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> indexWhere(Function1<A, bool> p, [int from = 0]) => iterator.indexWhere(p, from);

indices() inherited ​

Range indices()

Returns a range of all indices of this sequence

Will force evaluation.

Inherited from RSeq.

Implementation
dart
Range indices() => Range.exclusive(0, length);

intersect() override ​

IList<A> intersect(RSeq<A> that)

Returns a new collection with the intersection of this and that, i.e. all elements that appear in both collections.

Implementation
dart
@override
IList<A> intersect(RSeq<A> that) => toIList().intersect(that);

intersperse() override ​

NonEmptyIList<A> intersperse(A x)

Returns a new collection with sep inserted between each element.

Implementation
dart
@override
NonEmptyIList<A> intersperse(A x) => NonEmptyIList.unsafe(toIList().intersperse(x));

isDefinedAt() inherited ​

bool isDefinedAt(int idx)

Returns true if this collection has an element at the given idx.

Inherited from RSeq.

Implementation
dart
bool isDefinedAt(int idx) => 0 <= idx && idx < size;

lastIndexOf() inherited ​

Option<int> lastIndexOf(A elem, [int end = 2147483647])

Returns the last index, if any, where the element at that index equals elem. If no index contains elem, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> lastIndexOf(A elem, [int end = 2147483647]) => lastIndexWhere((a) => a == elem, end);

lastIndexOfSlice() inherited ​

Option<int> lastIndexOfSlice(RSeq<A> that, [int end = 2147483647])

Finds the last index in this collection where the next sequence of elements is equal to that. If that cannot be found in this collection, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> lastIndexOfSlice(RSeq<A> that, [int end = 2147483647]) {
  final l = length;
  final tl = that.length;
  final clippedL = min(l - tl, end);

  if (end < 0) {
    return none();
  } else if (tl < 1) {
    return Some(clippedL);
  } else if (l < tl) {
    return none();
  } else {
    return _kmpSearch(this, 0, clippedL + tl, that, 0, tl, false);
  }
}

lastIndexWhere() inherited ​

Option<int> lastIndexWhere(bool Function(A) p, [int end = 2147483647])

Returns the index of the last element that satisfies the predicate p. If no element satisfies, None is returned.

Inherited from RSeq.

Implementation
dart
Option<int> lastIndexWhere(Function1<A, bool> p, [int end = 2147483647]) {
  var i = length - 1;
  final it = reverseIterator();

  while (it.hasNext) {
    final elem = it.next();

    if (i < end && p(elem)) return Some(i);

    i -= 1;
  }

  return none();
}

lift() inherited ​

Option<A> lift(int ix)

Returns the element at index ix as a Some. If ix is outside the range of this collection, None is returned.

Inherited from RSeq.

Implementation
dart
Option<A> lift(int ix) => Option.when(() => isDefinedAt(ix), () => this[ix]);

map() override ​

NonEmptyIList<B> map<B>(B Function(A) f)

Returns a new collection by applying f to each element.

Implementation
dart
@override
NonEmptyIList<B> map<B>(Function1<A, B> f) => NonEmptyIList(f(head), _tail.map(f));

maxByOption() inherited ​

Option<A> maxByOption<B>(B Function(A) f, Order<B> order)

Finds the largest element in this collection by applying f to each element and using the given Order to find the greatest.

If this collection is empty, None is returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> maxByOption<B>(Function1<A, B> f, Order<B> order) => _minMaxByOption(f, order.max);

maxOption() inherited ​

Option<A> maxOption(Order<A> order)

Finds the largest element in this collection according to the given Order.

If this collection is empty, None is returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> maxOption(Order<A> order) => switch (knownSize) {
  0 => none(),
  _ => _reduceOptionIterator(iterator, order.max),
};

minByOption() inherited ​

Option<A> minByOption<B>(B Function(A) f, Order<B> order)

Finds the smallest element in this collection by applying f to each element and using the given Order to find the greatest.

If this collection is empty, None is returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> minByOption<B>(Function1<A, B> f, Order<B> order) => _minMaxByOption(f, order.min);

minOption() inherited ​

Option<A> minOption(Order<A> order)

Finds the largest element in this collection according to the given Order.

If this collection is empty, None is returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> minOption(Order<A> order) => switch (knownSize) {
  0 => none(),
  _ => _reduceOptionIterator(iterator, order.min),
};

mkString() inherited ​

String mkString({String? start, String? sep, String? end})

Returns a String by using each elements toString(), adding sep between each element. If start is defined, it will be prepended to the resulting string. If end is defined, it will be appended to the resulting string.

Inherited from RIterableOnce.

Implementation
dart
String mkString({String? start, String? sep, String? end}) {
  if (knownSize == 0) {
    return '${start ?? ""}${end ?? ""}';
  } else {
    return _mkStringImpl(StringBuffer(), start ?? '', sep ?? '', end ?? '');
  }
}

noSuchMethod() inherited ​

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dart
dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

dart
class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation
dart
@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

padTo() override ​

NonEmptyIList<A> padTo(int len, A elem)

Returns a new collection with a length of at least len.

If this collection is shorter than len, the returned collection will have size len and elem will be used for each new element needed to reach that size.

If this collection is already at least len in size, this collection will be returned.

Implementation
dart
@override
NonEmptyIList<A> padTo(int len, A elem) =>
    size >= len ? this : NonEmptyIList(head, _tail.padTo(len - 1, elem));

partition() override ​

Record partition(bool Function(A) p)

Returns 2 collections as a tuple where the first tuple element will be a collection of elements that satisfy the given predicate p. The second item of the returned tuple will be elements that do not satisfy p.

Implementation
dart
@override
(IList<A>, IList<A>) partition(Function1<A, bool> p) => toIList().partition(p);

partitionMap() override ​

Record partitionMap<A1, A2>(Either<A1, A2> Function(A) f)

Applies f to each element of this collection and returns a separate collection for all applications resulting in a Left and Right respectively.

Implementation
dart
@override
(IList<A1>, IList<A2>) partitionMap<A1, A2>(Function1<A, Either<A1, A2>> f) =>
    toIList().partitionMap(f);

patch() override ​

IList<A> patch(int from, RIterableOnce<A> other, int replaced)

Returns a new collection with replaced elements starting at from replaced by the elements of other.

Implementation
dart
@override
IList<A> patch(int from, RIterableOnce<A> other, int replaced) =>
    toIList().patch(from, other, replaced);

permutations() override ​

RIterator<NonEmptyIList<A>> permutations()

Returns an Iterator that will emit all possible permutations of the elements in this collection.

Note that only distinct permutations are emitted. Given the example [1, 2, 2, 2] the permutations will only include [1, 2, 2, 2] once, even though there are 3 different way to generate that permutation.

Implementation
dart
@override
RIterator<NonEmptyIList<A>> permutations() => toIList().permutations().map(NonEmptyIList.unsafe);

prepended() override ​

NonEmptyIList<A> prepended(A elem)

Returns a new collection with elem added to the beginning.

Implementation
dart
@override
NonEmptyIList<A> prepended(A elem) => NonEmptyIList(elem, toIList());

prependedAll() override ​

NonEmptyIList<A> prependedAll(RIterableOnce<A> prefix)

Returns a new collection with all elems added to the beginning.

Implementation
dart
@override
NonEmptyIList<A> prependedAll(RIterableOnce<A> prefix) =>
    NonEmptyIList.unsafe(toIList().prependedAll(prefix));

reduce() inherited ​

A reduce(A Function(A, A) op)

Reduces this collection to a single value by applying op left to right.

Throws if the collection is empty.

Inherited from RIterableOnce.

Implementation
dart
A reduce(Function2<A, A, A> op) => reduceLeft(op);

reduceLeft() inherited ​

A reduceLeft(A Function(A, A) op)

Reduces from left to right. Throws if empty.

Inherited from RIterableOnce.

Implementation
dart
A reduceLeft(Function2<A, A, A> op) => switch (this) {
  final IndexedSeq<A> seq when seq.length > 0 => _foldl(seq, 1, seq[0], op),
  _ when knownSize == 0 => throw UnsupportedError('empty.reduceLeft'),
  _ => _reduceLeftIterator(() => throw UnsupportedError('empty.reduceLeft'), op),
};

reduceLeftOption() inherited ​

Option<A> reduceLeftOption(A Function(A, A) op)

Returns a summary values of all elements of this collection by applying f to each element, moving left to right.

If this collection is empty, None will be returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> reduceLeftOption(Function2<A, A, A> op) => switch (knownSize) {
  0 => none(),
  _ => _reduceOptionIterator(iterator, op),
};

reduceOption() inherited ​

Option<A> reduceOption(A Function(A, A) op)

Returns a summary values of all elements of this collection by applying f to each element, moving left to right.

If this collection is empty, None will be returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> reduceOption(Function2<A, A, A> op) => reduceLeftOption(op);

reduceRight() inherited ​

A reduceRight(A Function(A, A) op)

Reduces from right to left. Throws if empty.

Inherited from RIterableOnce.

Implementation
dart
A reduceRight(Function2<A, A, A> op) => switch (this) {
  final IndexedSeq<A> seq when seq.length > 0 => _foldr(seq, op),
  _ when knownSize == 0 => throw UnsupportedError('empty.reduceLeft'),
  _ => _reversed().reduceLeft((x, y) => op(y, x)),
};

reduceRightOption() inherited ​

Option<A> reduceRightOption(A Function(A, A) op)

Returns a summary values of all elements of this collection by applying f to each element, moving right to left.

If this collection is empty, None will be returned.

Inherited from RIterableOnce.

Implementation
dart
Option<A> reduceRightOption(Function2<A, A, A> op) => switch (knownSize) {
  -1 => _reduceOptionIterator(_reversed().iterator, (x, y) => op(y, x)),
  0 => none(),
  _ => Some(reduceRight(op)),
};

removeAt() override ​

IList<A> removeAt(int idx)

Returns a new collection with the element at idx removed.

Throws RangeError if idx is out of bounds.

Implementation
dart
@override
IList<A> removeAt(int idx) => toIList().removeAt(idx);

removeFirst() ​

IList<A> removeFirst(bool Function(A) p)

Returns a new list with the first element satisfying p removed.

Returns this list unchanged if no element matches.

Implementation
dart
IList<A> removeFirst(Function1<A, bool> p) => toIList().removeFirst(p);

reverse() override ​

NonEmptyIList<A> reverse()

Returns a new collection with the order of the elements reversed.

Implementation
dart
@override
NonEmptyIList<A> reverse() =>
    _tail.isEmpty
        ? this
        : NonEmptyIList(
          _tail.lastOption.getOrElse(() => head),
          _tail.init.reverse().appended(head),
        );

reverseIterator() inherited ​

RIterator<A> reverseIterator()

Returns an iterator that will emit all elements in this collection, in reverse order.

Inherited from RSeq.

Implementation
dart
RIterator<A> reverseIterator() => reverse().iterator;

sameElements() inherited ​

bool sameElements(RIterable<A> that)

Returns true if this collection has the same elements, in the same order, as that.

Inherited from RSeq.

Implementation
dart
bool sameElements(RIterable<A> that) {
  final thisKnownSize = knownSize;
  final thatKnownSize = that.knownSize;
  final knownDifference =
      thisKnownSize != -1 && thatKnownSize != -1 && thisKnownSize != thatKnownSize;

  return !knownDifference && iterator.sameElements(that);
}

scan() override ​

NonEmptyIList<B> scan<B>(B z, B Function(B, A) op)

Alias for scanLeft.

Implementation
dart
@override
NonEmptyIList<B> scan<B>(B z, Function2<B, A, B> op) => scanLeft(z, op);

scanLeft() override ​

NonEmptyIList<B> scanLeft<B>(B z, B Function(B, A) op)

Returns a new collection of running totals starting with z.

The first element of the result is z; each subsequent element is the result of applying op to the previous total and the next element.

Implementation
dart
@override
NonEmptyIList<B> scanLeft<B>(B z, Function2<B, A, B> op) =>
    NonEmptyIList(z, _tail.scanLeft(op(z, head), op));

scanRight() override ​

NonEmptyIList<B> scanRight<B>(B z, B Function(A, B) op)

Returns a new collection of running totals starting with z, traversing from right to left.

Implementation
dart
@override
NonEmptyIList<B> scanRight<B>(B z, Function2<A, B, B> op) {
  final newTail = _tail.scanRight(z, op);

  return newTail.headOption.fold(
    () => NonEmptyIList(op(head, z), ilist([z])),
    (h) => NonEmptyIList(op(head, h), newTail),
  );
}

segmentLength() inherited ​

int segmentLength(bool Function(A) p, [int from = 0])

Returns the length of the longest prefix starting at from where every element satisfies p.

Inherited from RSeq.

Implementation
dart
int segmentLength(Function1<A, bool> p, [int from = 0]) {
  var i = 0;
  final it = iterator.drop(from);

  while (it.hasNext && p(it.next())) {
    i += 1;
  }

  return i;
}

slice() inherited ​

RIterable<A> slice(int from, int until)

Returns a new collection containing elements in the range [from, until).

Inherited from RIterable.

Implementation
dart
@override
RIterable<A> slice(int from, int until) => views.Drop(views.Take(this, until), from);

sliding() override ​

RIterator<IList<A>> sliding(int size, [int step = 1])

Returns an iterator where elements are fixed size chunks of size n of the original collection. Each chunk is calculated by sliding a 'window' of size n over the original collection, moving the window step elements at a time.

Implementation
dart
@override
RIterator<IList<A>> sliding(int size, [int step = 1]) => toIList().sliding(size, step);

sortBy() override ​

NonEmptyIList<A> sortBy<B>(Order<B> order, B Function(A) f)

Returns a new collection that is sorted according to order after applying f to each element in this collection.

Implementation
dart
@override
NonEmptyIList<A> sortBy<B>(Order<B> order, Function1<A, B> f) =>
    NonEmptyIList.unsafe(super.sortBy(order, f));

sorted() override ​

NonEmptyIList<A> sorted(Order<A> order)

Returns a new collection that is sorted according to order.

Implementation
dart
@override
NonEmptyIList<A> sorted(Order<A> order) => fromDartUnsafe(toIList().sorted(order).toList());

sortWith() override ​

NonEmptyIList<A> sortWith(bool Function(A, A) lt)

Returns a new collection sorted using the provided function lt which is used to determine if one element is less than the other.

Implementation
dart
@override
NonEmptyIList<A> sortWith(Function2<A, A, bool> lt) =>
    fromDartUnsafe(toIList().sortWith(lt).toList());

span() override ​

Record span(bool Function(A) p)

Returns two collections: elements before and starting from the first element that does not satisfy p.

Implementation
dart
@override
(IList<A>, IList<A>) span(Function1<A, bool> p) => toIList().span(p);

splitAt() override ​

Record splitAt(int n)

Returns two collections: the first n elements and the remainder.

Implementation
dart
@override
(IList<A>, IList<A>) splitAt(int n) => toIList().splitAt(n);

startsWith() inherited ​

bool startsWith(RIterableOnce<A> that, [int offset = 0])

Returns true if the beginning of this collection corresponds with that.

Inherited from RSeq.

Implementation
dart
bool startsWith(RIterableOnce<A> that, [int offset = 0]) {
  final i = iterator.drop(offset);
  final j = that.iterator;
  while (j.hasNext && i.hasNext) {
    if (i.next() != j.next()) return false;
  }

  return !j.hasNext;
}

startsWithNel() ​

bool startsWithNel(NonEmptyIList<A> that, [int offset = 0])

Checks if the beginning of this NonEmptyIList corresponds to the given NonEmptyIList.

Implementation
dart
bool startsWithNel(NonEmptyIList<A> that, [int offset = 0]) =>
    head == that.head && _tail.startsWith(that._tail, offset);

take() override ​

IList<A> take(int n)

Returns a new collection containing only the first n elements.

Implementation
dart
@override
IList<A> take(int n) => toIList().take(n);

takeRight() override ​

IList<A> takeRight(int n)

Returns a new collection with the last n elements of this collection. If n is greater than the size of this collection, the original collection is returned.

Implementation
dart
@override
IList<A> takeRight(int n) => toIList().takeRight(n);

takeWhile() override ​

IList<A> takeWhile(bool Function(A) p)

Returns a new collection of leading elements that satisfy p.

Implementation
dart
@override
IList<A> takeWhile(Function1<A, bool> p) => toIList().takeWhile(p);

tapEach() override ​

NonEmptyIList<A> tapEach<U>(U Function(A) f)

Applies f to each element in this collection, discarding any results and returns this collection.

Implementation
dart
@override
NonEmptyIList<A> tapEach<U>(Function1<A, U> f) {
  foreach(f);
  return this;
}

toIList() override ​

IList<A> toIList()

Returns an IList with the same elements as this collection.

Implementation
dart
@override
IList<A> toIList() => _tail.prepended(head);

toIndexedSeq() inherited ​

IndexedSeq<A> toIndexedSeq()

Returns an IndexedSeq with the same elements as this collection.

Inherited from RIterableOnce.

Implementation
dart
IndexedSeq<A> toIndexedSeq() => IndexedSeq.from(this);

toISet() inherited ​

ISet<A> toISet()

Returns an ISet with the same elements as this collection, duplicates removed.

Inherited from RIterableOnce.

Implementation
dart
ISet<A> toISet() => ISet.from(this);

toIVector() inherited ​

IVector<A> toIVector()

Returns an IVector with the same elements as this collection.

Inherited from RIterableOnce.

Implementation
dart
IVector<A> toIVector() => IVector.from(this);

toList() inherited ​

List<A> toList({bool growable = true})

Returns a new List with the same elements as this collection.

Inherited from RIterableOnce.

Implementation
dart
List<A> toList({bool growable = true}) {
  if (growable) {
    final it = iterator;
    final res = List<A>.empty(growable: true);

    while (it.hasNext) {
      res.add(it.next());
    }

    return res;
  } else {
    final it = iterator;
    return List.generate(size, (_) => it.next());
  }
}

toSeq() inherited ​

RSeq<A> toSeq()

Returns a RSeq with the same elements as this collection.

Inherited from RIterableOnce.

Implementation
dart
RSeq<A> toSeq() => RSeq.from(this);

toString() override ​

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Implementation
dart
@override
String toString() => mkString(start: 'NonEmptyIList(', sep: ', ', end: ')');

traverseEither() override ​

Either<B, NonEmptyIList<C>> traverseEither<B, C>(Either<B, C> Function(A) f)

Applies f to each element of this RSeq and collects the results into a new collection. If Left is encountered for any element, that result is returned and any additional elements will not be evaluated.

Implementation
dart
@override
Either<B, NonEmptyIList<C>> traverseEither<B, C>(Function1<A, Either<B, C>> f) =>
    super.traverseEither(f).map(NonEmptyIList.unsafe);

traverseOption() override ​

Option<NonEmptyIList<B>> traverseOption<B>(Option<B> Function(A) f)

Applies f to each element of this RSeq and collects the results into a new collection. If None is encountered for any element, that result is returned and any additional elements will not be evaluated.

Implementation
dart
@override
Option<NonEmptyIList<B>> traverseOption<B>(Function1<A, Option<B>> f) =>
    super.traverseOption(f).map(NonEmptyIList.unsafe);

updated() override ​

NonEmptyIList<A> updated(int index, A elem)

Returns a new list with f applied to the element at index index.

If index is outside the range of this list, the original list is returned.

Implementation
dart
@override
NonEmptyIList<A> updated(int index, A elem) {
  if (index == 0) {
    return NonEmptyIList(elem, _tail);
  } else if (1 <= index && index < size) {
    return NonEmptyIList(head, _tail.updated(index - 1, elem));
  } else {
    return this;
  }
}

zip() override ​

IList<Record> zip<B>(RIterableOnce<B> that)

Returns a new collection that combines corresponding elements from this collection and that as a tuple. The length of the returned collection will be the minimum of this collections size and the size of that.

Implementation
dart
@override
IList<(A, B)> zip<B>(RIterableOnce<B> that) => toIList().zip(that);

zipAll() override ​

NonEmptyIList<Record> zipAll<B>(RIterableOnce<B> that, A thisElem, B thatElem)

Returns a new collection that combines corresponding elements from this collection and that as a tuple. The length of the returned collection will be the maximum of this collections size and thes size of that. If this collection is shorter than that, thisElem will be used to fill in the resulting collection. If that is shorter, thatElem will be used to will in the resulting collection.

Implementation
dart
@override
NonEmptyIList<(A, B)> zipAll<B>(
  RIterableOnce<B> that,
  A thisElem,
  B thatElem,
) => NonEmptyIList.unsafe(super.zipAll(that, thisElem, thatElem));

zipWithIndex() override ​

NonEmptyIList<Record> zipWithIndex()

Return a new collection with each element of this collection paired with it's respective index.

Implementation
dart
@override
NonEmptyIList<(A, int)> zipWithIndex() =>
    NonEmptyIList((head, 0), _tail.zipWithIndex().map((a) => a.copy($2: a.$2 + 1)));

Extension Methods ​

flatten() extension ​

RIterable<A> flatten()

Concatenates all inner iterables into a single IList.

Available on RIterable<A>, provided by the RIterableNested2Ops<A> extension

Implementation
dart
RIterable<A> flatten() {
  final it = iterator;
  final b = IList.builder<A>();

  while (it.hasNext) {
    b.addAll(it.next());
  }

  return b.toIList();
}

flatten() extension ​

NonEmptyIList<A> flatten()

Combines all nested lists into one list using concatenation.

Available on NonEmptyIList<A>, provided by the NonEmptyIListNestedOps<A> extension

Implementation
dart
NonEmptyIList<A> flatten() => head.concat(_tail.flatMap((a) => a.toIList()));

flatTraverseIO() extension ​

IO<IList<B>> flatTraverseIO<B>(IO<IList<B>> Function(A) f)

Applies f to each element of this list and collects the results into a new list that is flattened using concatenation. If an error or cancelation is encountered for any element, that result is returned and any additional elements will not be evaluated.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<IList<B>> flatTraverseIO<B>(Function1<A, IO<IList<B>>> f) => toIList().flatTraverseIO(f);

parSequence() extension ​

IO<NonEmptyIList<A>> parSequence()

Alias for parTraverseIO, using identity as the function parameter.

Available on NonEmptyIList<A>, provided by the NonEmptyIListIOOps<A> extension

Implementation
dart
IO<NonEmptyIList<A>> parSequence() => parTraverseIO(identity);

parSequence_() extension ​

IO<Unit> parSequence_()

Alias for parTraverseIO_, using identity as the function parameter.

Available on NonEmptyIList<A>, provided by the NonEmptyIListIOOps<A> extension

Implementation
dart
IO<Unit> parSequence_() => parTraverseIO_(identity);

parTraverseIO() extension ​

IO<NonEmptyIList<B>> parTraverseIO<B>(IO<B> Function(A) f)

Asynchronously applies f to each element of this list and collects the results into a new list. If an error or cancelation is encountered for any element, that result is returned and all other elements will be canceled if possible.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<NonEmptyIList<B>> parTraverseIO<B>(Function1<A, IO<B>> f) =>
    IO.both(f(head), tail.parTraverseIO(f)).map((t) => NonEmptyIList(t.$1, t.$2));

parTraverseIO_() extension ​

IO<Unit> parTraverseIO_<B>(IO<B> Function(A) f)

Asynchronously applies f to each element of this list, discarding any results. If an error or cancelation is encountered for any element, that result is returned and all other elements will be canceled if possible.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<Unit> parTraverseIO_<B>(Function1<A, IO<B>> f) => toIList().parTraverseIO_(f);

product() extension ​

int product()

Returns the product of all elements in this list

Available on RIterableOnce<A>, provided by the RIterableIntOps extension

Implementation
dart
int product() {
  var p = 1;
  final it = iterator;

  while (it.hasNext) {
    p *= it.next();
  }

  return p;
}

product() extension ​

double product()

Returns the product of all elements in this list

Available on RIterableOnce<A>, provided by the RIterableDoubleOps extension

Implementation
dart
double product() {
  var p = 1.0;
  final it = iterator;

  while (it.hasNext) {
    p *= it.next();
  }

  return p;
}

sequence() extension ​

Either<A, NonEmptyIList<B>> sequence()

Sequences this list of Either values into a single Either.

Returns the first Left encountered, or a Right wrapping the list of all Right values if no Left is present.

Available on NonEmptyIList<A>, provided by the NonEmptyIListEitherOps<A, B> extension

Implementation
dart
Either<A, NonEmptyIList<B>> sequence() => traverseEither(identity);

sequence() extension ​

IO<NonEmptyIList<A>> sequence()

Alias for traverseIO, using identity as the function parameter.

Available on NonEmptyIList<A>, provided by the NonEmptyIListIOOps<A> extension

Implementation
dart
IO<NonEmptyIList<A>> sequence() => traverseIO(identity);

sequence() extension ​

Option<NonEmptyIList<A>> sequence()

Accumulates all elements in this list as one Option. If any element is a None, None will be returned. If all elements are Some, then the entire list is returned, wrapped in a Some.

Available on NonEmptyIList<A>, provided by the NonEmptyIListOptionOps<A> extension

Implementation
dart
Option<NonEmptyIList<A>> sequence() => traverseOption(identity);

sequence_() extension ​

IO<Unit> sequence_()

Alias for traverseIO_, using identity as the function parameter.

Available on NonEmptyIList<A>, provided by the NonEmptyIListIOOps<A> extension

Implementation
dart
IO<Unit> sequence_() => traverseIO_(identity);

sum() extension ​

double sum()

Returns the sum of all elements in this list

Available on RIterableOnce<A>, provided by the RIterableDoubleOps extension

Implementation
dart
double sum() {
  var s = 0.0;
  final it = iterator;

  while (it.hasNext) {
    s += it.next();
  }

  return s;
}

sum() extension ​

int sum()

Returns the sum of all elements in this list

Available on RIterableOnce<A>, provided by the RIterableIntOps extension

Implementation
dart
int sum() {
  var s = 0;
  final it = iterator;

  while (it.hasNext) {
    s += it.next();
  }

  return s;
}

toIMap() extension ​

IMap<A, B> toIMap()

Creates a new IMap where element tuple element of this list is used to create a key and value respectively.

Available on RIterable<A>, provided by the RIterableTuple2Ops<A, B> extension

Implementation
dart
IMap<A, B> toIMap() => IMap.from(this);

traverseFilterIO() extension ​

IO<IList<B>> traverseFilterIO<B>(IO<Option<B>> Function(A) f)

Applies f to each element of this list and collects the results into a new list. Any results from f that are None are discarded from the resulting list. If an error or cancelation is encountered for any element, that result is returned and any additional elements will not be evaluated.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<IList<B>> traverseFilterIO<B>(Function1<A, IO<Option<B>>> f) => toIList().traverseFilterIO(f);

traverseIO() extension ​

IO<NonEmptyIList<B>> traverseIO<B>(IO<B> Function(A) f)

Applies f to each element of this list and collects the results into a new list. If an error or cancelation is encountered for any element, that result is returned and any additional elements will not be evaluated.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<NonEmptyIList<B>> traverseIO<B>(Function1<A, IO<B>> f) =>
    f(head).flatMap((h) => tail.traverseIO(f).map((t) => NonEmptyIList(h, t)));

traverseIO_() extension ​

IO<Unit> traverseIO_<B>(IO<B> Function(A) f)

Applies f to each element of this list, discarding any results. If an error or cancelation is encountered for any element, that result is returned and any additional elements will not be evaluated.

Available on NonEmptyIList<A>, provided by the IONonEmptyIListOps<A> extension

Implementation
dart
IO<Unit> traverseIO_<B>(Function1<A, IO<B>> f) => toIList().traverseIO_(f);

unzip() extension ​

Record unzip()

Splits a collection of pairs into two separate collections.

Available on RIterable<A>, provided by the RibsIterableTuple2Ops<A, B> extension

Implementation
dart
(RIterable<A>, RIterable<B>) unzip() => (
  views.Map(this, (a) => a.$1),
  views.Map(this, (a) => a.$2),
);

Operators ​

operator ==() override ​

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

  • Total: It must return a boolean for all arguments. It should never throw.

  • Reflexive: For all objects o, o == o must be true.

  • Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

  • Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Implementation
dart
@override
bool operator ==(Object other) {
  if (identical(this, other)) {
    return true;
  } else if (other is NonEmptyIList) {
    if (head != other.head) {
      return false;
    }

    var a = _tail;
    var b = other._tail;

    while (a.nonEmpty && b.nonEmpty && a.head == b.head) {
      a = a.tail;
      b = b.tail;
    }

    return a.isEmpty && b.isEmpty;
  } else {
    return super == other;
  }
}

operator override ​

A operator [](int ix)

Returns the element at index idx.

Implementation
dart
@override
A operator [](int ix) => ix == 0 ? head : _tail[ix - 1];

Static Methods ​

from() override ​

Option<NonEmptyIList<A>> from<A>(RIterableOnce<A> as)

Returns Some wrapping a NonEmptyIList when as is non-empty, or None when empty.

Implementation
dart
static Option<NonEmptyIList<A>> from<A>(RIterableOnce<A> as) =>
    Option.when(() => as.nonEmpty, () {
      final l = as.toIList();
      return NonEmptyIList(l.head, l.tail);
    });

fromDart() override ​

Option<NonEmptyIList<A>> fromDart<A>(Iterable<A> as)

If the given Iterable is non-empty, a NonEmptyIList wrapped in a Some is returned. If the Iterable is empty, None is returned.

dart
assert(NonEmptyIList.fromDart([1, 2, 3]) == Some(nel(1, [2, 3])));
assert(NonEmptyIList.fromDart([]) == None());
Implementation
dart
static Option<NonEmptyIList<A>> fromDart<A>(Iterable<A> as) => Option.when(
  () => as.isNotEmpty,
  () => NonEmptyIList(as.first, as.toIList().tail),
);

fromDartUnsafe() ​

NonEmptyIList<A> fromDartUnsafe<A>(Iterable<A> as)

Returns a NonEmptyIList with all elements from the given Iterable if the Iterable is non-empty. If the Iterable is empty, an ArgumentError will be thrown.

Implementation
dart
static NonEmptyIList<A> fromDartUnsafe<A>(Iterable<A> as) =>
    fromDart(as).getOrElse(() => throw ArgumentError('NonEmptyList.fromDartUnsafe: empty'));

one() ​

NonEmptyIList<A> one<A>(A head)

Creates a NonEmptyIList with a single element.

Implementation
dart
static NonEmptyIList<A> one<A>(A head) => nel(head);

unsafe() ​

NonEmptyIList<A> unsafe<A>(RIterableOnce<A> as)

Returns a NonEmptyIList from as, or throws ArgumentError if empty.

Implementation
dart
static NonEmptyIList<A> unsafe<A>(RIterableOnce<A> as) =>
    from(as).getOrElse(() => throw ArgumentError('NonEmptyList.fromUnsafe: empty'));