Returns a new NonEmptySet
with the given element added.
Returns a new NonEmptySet
with the given element added.
the first element to add.
the second element to add.
the remaining elements to add.
a new NonEmptySet
with the given elements added, omitting duplicates.
Returns a new NonEmptySet
with the given element added.
Returns a new NonEmptySet
with the given element added.
the element to add to this NonEmptySet
a new NonEmptySet
consisting of element
and all elements of this NonEmptySet
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed GenTraversableOnce
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed GenTraversableOnce
.
The element type of the resulting NonEmptySet
is the most specific superclass encompassing the element types of this NonEmptySet
and the passed GenTraversableOnce
.
the GenTraversableOnce
to append
a new NonEmptySet
that contains all the elements of this NonEmptySet
followed by all elements of other
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed Every
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed Every
.
The element type of the resulting NonEmptySet
is the most specific superclass encompassing the element types of this NonEmptySet
and the passed Every
.
the element type of the returned NonEmptySet
the Every
to append
a new NonEmptySet
that contains all the elements of this NonEmptySet
followed by all elements of other
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed NonEmptySet
.
Returns a new NonEmptySet
containing the elements of this NonEmptySet
followed by the elements of the passed NonEmptySet
.
The element type of the resulting NonEmptySet
is the most specific superclass encompassing the element types of this and the passed NonEmptySet
.
the element type of the returned NonEmptySet
the NonEmptySet
to append
a new NonEmptySet
that contains all the elements of this NonEmptySet
followed by all elements of other
.
Appends all elements of this NonEmptySet
to a string builder using start, end, and separator strings.
Appends all elements of this NonEmptySet
to a string builder using start, end, and separator strings. The written text will consist of a concatenation of
the string start
; the result of invoking toString
on all elements of this NonEmptySet
,
separated by the string sep
; and the string end
the string builder to which elements will be appended
the ending string
the separator string
the string builder, sb
, to which elements were appended.
Appends all elements of this NonEmptySet
to a string builder using a separator string.
Appends all elements of this NonEmptySet
to a string builder using a separator string. The written text will consist of a concatenation of the
result of invoking toString
on of every element of this NonEmptySet
, separated by the string sep
.
the string builder to which elements will be appended
the separator string
the string builder, sb
, to which elements were appended.
Appends all elements of this NonEmptySet
to a string builder.
Appends all elements of this NonEmptySet
to a string builder. The written text will consist of a concatenation of the result of invoking toString
on of every element of this NonEmptySet
, without any separator string.
the string builder to which elements will be appended
the string builder, sb
, to which elements were appended.
Check if an element exists at its index in the NonEmptySet
.
Check if an element exists at its index in the NonEmptySet
.
true
if a element exists in NonEmptySet
at index idx
, where false
indicates the element at index idx
does not exist.
Finds the first element of this NonEmptySet
for which the given partial function is defined, if any, and applies the partial function to it.
Finds the first element of this NonEmptySet
for which the given partial function is defined, if any, and applies the partial function to it.
the partial function
an Option
containing pf
applied to the first element for which it is defined, or None
if
the partial function was not defined for any element.
Indicates whether this NonEmptySet
contains a given value as an element.
Indicates whether this NonEmptySet
contains a given value as an element.
the element to look for
true if this NonEmptySet
has an element that is equal (as determined by ==)
to elem
, false otherwise.
Copies values of this NonEmptySet
to an array.
Copies values of this NonEmptySet
to an array. Fills the given array arr
with at most len
elements of this NonEmptySet
, beginning at
index start
. Copying will stop once either the end of the current NonEmptySet
is reached, the end of the array is reached, or
len
elements have been copied.
the array to fill
the starting index
the maximum number of elements to copy
Copies values of this NonEmptySet
to an array.
Copies values of this NonEmptySet
to an array. Fills the given array arr
with values of this NonEmptySet
, beginning at
index start
. Copying will stop once either the end of the current NonEmptySet
is reached, or the end of the array is reached.
the array to fill
the starting index
Copies values of this NonEmptySet
to an array.
Copies values of this NonEmptySet
to an array. Fills the given array arr
with values of this NonEmptySet
. Copying
will stop once either the end of the current NonEmptySet
is reached, or the end of the array is reached.
the array to fill
Copies all elements of this NonEmptySet
to a buffer.
Copies all elements of this NonEmptySet
to a buffer.
the buffer to which elements are copied
Counts the number of elements in this NonEmptySet
that satisfy a predicate.
Counts the number of elements in this NonEmptySet
that satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p
.
Indicates whether a predicate holds for at least one of the elements of this NonEmptySet
.
Indicates whether a predicate holds for at least one of the elements of this NonEmptySet
.
the predicate used to test elements.
true
if the given predicate p
holds for some of the elements of this NonEmptySet
, otherwise false
.
Finds the first element of this NonEmptySet
that satisfies the given predicate, if any.
Finds the first element of this NonEmptySet
that satisfies the given predicate, if any.
the predicate used to test elements
an Some
containing the first element in this NonEmptySet
that satisfies p
, or None
if none exists.
Builds a new NonEmptySet
by applying a function to all elements of this NonEmptySet
and using the elements of the resulting NonEmptySet
s.
Builds a new NonEmptySet
by applying a function to all elements of this NonEmptySet
and using the elements of the resulting NonEmptySet
s.
the element type of the returned NonEmptySet
the function to apply to each element.
a new NonEmptySet
containing elements obtained by applying the given function f
to each element of this NonEmptySet
and concatenating
the elements of resulting NonEmptySet
s.
Converts this NonEmptySet
of NonEmptySet
s into a NonEmptySet
formed by the elements of the nested NonEmptySet
s.
Converts this NonEmptySet
of NonEmptySet
s into a NonEmptySet
formed by the elements of the nested NonEmptySet
s.
Note: You cannot use this flatten
method on a NonEmptySet
that contains a GenTraversableOnce
s, because
if all the nested GenTraversableOnce
s were empty, you'd end up with an empty NonEmptySet
.
a new NonEmptySet
resulting from concatenating all nested NonEmptySet
s.
Folds the elements of this NonEmptySet
using the specified associative binary operator.
Folds the elements of this NonEmptySet
using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
a type parameter for the binary operator, a supertype of T.
a neutral element for the fold operation; may be added to the result an arbitrary number of
times, and must not change the result (e.g., Nil
for Set concatenation,
0 for addition, or 1 for multiplication.)
a binary operator that must be associative
the result of applying fold operator op
between all the elements and z
Applies a binary operator to a start value and all elements of this NonEmptySet
, going left to right.
Applies a binary operator to a start value and all elements of this NonEmptySet
, going left to right.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this NonEmptySet
, going left to right, with the start value,
z
, on the left:
op(...op(op(z, x_1), x_2), ..., x_n)where x1, ..., xn are the elements of this
NonEmptySet
.Applies a binary operator to all elements of this NonEmptySet
and a start value, going right to left.
Applies a binary operator to all elements of this NonEmptySet
and a start value, going right to left.
the result of the binary operator
the start value
the binary operator
the result of inserting op
between consecutive elements of this NonEmptySet
, going right to left, with the start value,
z
, on the right:
op(x_1, op(x_2, ... op(x_n, z)...))where x1, ..., xn are the elements of this
NonEmptySet
.Indicates whether a predicate holds for all elements of this NonEmptySet
.
Indicates whether a predicate holds for all elements of this NonEmptySet
.
the predicate used to test elements.
true
if the given predicate p
holds for all elements of this NonEmptySet
, otherwise false
.
Applies a function f
to all elements of this NonEmptySet
.
Applies a function f
to all elements of this NonEmptySet
.
the function that is applied for its side-effect to every element. The result of function f
is discarded.
Partitions this NonEmptySet
into a map of NonEmptySet
s according to some discriminator function.
Partitions this NonEmptySet
into a map of NonEmptySet
s according to some discriminator function.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to NonEmptySet
s such that the following invariant holds:
(NonEmptySet.toSet partition f)(k) = xs filter (x => f(x) == k)That is, every key
k
is bound to a NonEmptySet
of those elements x
for which f(x)
equals k
.Partitions elements into fixed size NonEmptySet
s.
Partitions elements into fixed size NonEmptySet
s.
the number of elements per group
An iterator producing NonEmptySet
s of size size
, except the last will be truncated if the elements don't divide evenly.
Returns true
to indicate this NonEmptySet
has a definite size, since all NonEmptySet
s are strict collections.
Returns true
to indicate this NonEmptySet
has a definite size, since all NonEmptySet
s are strict collections.
Selects the first element of this NonEmptySet
.
Selects the first element of this NonEmptySet
.
the first element of this NonEmptySet
.
Selects the first element of this NonEmptySet
and returns it wrapped in a Some
.
Selects the first element of this NonEmptySet
and returns it wrapped in a Some
.
the first element of this NonEmptySet
, wrapped in a Some
.
Returns false
to indicate this NonEmptySet
, like all NonEmptySet
s, is non-empty.
Returns false
to indicate this NonEmptySet
, like all NonEmptySet
s, is non-empty.
false
Returns true
to indicate this NonEmptySet
, like all NonEmptySet
s, can be traversed repeatedly.
Returns true
to indicate this NonEmptySet
, like all NonEmptySet
s, can be traversed repeatedly.
true
Creates and returns a new iterator over all elements contained in this NonEmptySet
.
Creates and returns a new iterator over all elements contained in this NonEmptySet
.
the new iterator
Selects the last element of this NonEmptySet
.
Selects the last element of this NonEmptySet
.
the last element of this NonEmptySet
.
Returns the last element of this NonEmptySet
, wrapped in a Some
.
Returns the last element of this NonEmptySet
, wrapped in a Some
.
the last element, wrapped in a Some
.
Builds a new NonEmptySet
by applying a function to all elements of this NonEmptySet
.
Builds a new NonEmptySet
by applying a function to all elements of this NonEmptySet
.
the element type of the returned NonEmptySet
.
the function to apply to each element.
a new NonEmptySet
resulting from applying the given function f
to each element of this NonEmptySet
and collecting the results.
Finds the largest element.
Finds the largest element.
the largest element of this NonEmptySet
.
Finds the largest result after applying the given function to every element.
Finds the largest result after applying the given function to every element.
the largest result of applying the given function to every element of this NonEmptySet
.
Finds the smallest element.
Finds the smallest element.
the smallest element of this NonEmptySet
.
Finds the smallest result after applying the given function to every element.
Finds the smallest result after applying the given function to every element.
the smallest result of applying the given function to every element of this NonEmptySet
.
Displays all elements of this NonEmptySet
in a string using start, end, and separator strings.
Displays all elements of this NonEmptySet
in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this NonEmptySet
. The resulting string begins with the string start
and ends with the string
end
. Inside, In the resulting string, the result of invoking toString
on all elements of this NonEmptySet
are
separated by the string sep
.
Displays all elements of this NonEmptySet
in a string using a separator string.
Displays all elements of this NonEmptySet
in a string using a separator string.
the separator string
a string representation of this NonEmptySet
. In the resulting string, the result of invoking toString
on all elements of this
NonEmptySet
are separated by the string sep
.
Displays all elements of this NonEmptySet
in a string.
Displays all elements of this NonEmptySet
in a string.
a string representation of this NonEmptySet
. In the resulting string, the result of invoking toString
on all elements of this
NonEmptySet
follow each other without any separator string.
Returns true
to indicate this NonEmptySet
, like all NonEmptySet
s, is non-empty.
Returns true
to indicate this NonEmptySet
, like all NonEmptySet
s, is non-empty.
true
The result of multiplying all the elements of this NonEmptySet
.
The result of multiplying all the elements of this NonEmptySet
.
This method can be invoked for any NonEmptySet[T]
for which an implicit Numeric[T]
exists.
the product of all elements
Reduces the elements of this NonEmptySet
using the specified associative binary operator.
Reduces the elements of this NonEmptySet
using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
a type parameter for the binary operator, a supertype of T.
a binary operator that must be associative.
the result of applying reduce operator op
between all the elements of this NonEmptySet
.
Applies a binary operator to all elements of this NonEmptySet
, going left to right.
Applies a binary operator to all elements of this NonEmptySet
, going left to right.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this NonEmptySet
, going left to right:
op(...op(op(x_1, x_2), x_3), ..., x_n)where x1, ..., xn are the elements of this
NonEmptySet
.Applies a binary operator to all elements of this NonEmptySet
, going left to right, returning the result in a Some
.
Applies a binary operator to all elements of this NonEmptySet
, going left to right, returning the result in a Some
.
the result type of the binary operator.
the binary operator.
a Some
containing the result of reduceLeft(op)
Applies a binary operator to all elements of this NonEmptySet
, going right to left.
Applies a binary operator to all elements of this NonEmptySet
, going right to left.
the result of the binary operator
the binary operator
the result of inserting op
between consecutive elements of this NonEmptySet
, going right to left:
op(x_1, op(x_2, ... op(x_{n-1}, x_n)...))where x1, ..., xn are the elements of this
NonEmptySet
.Applies a binary operator to all elements of this NonEmptySet
, going right to left, returning the result in a Some
.
Applies a binary operator to all elements of this NonEmptySet
, going right to left, returning the result in a Some
.
the result of the binary operator
the binary operator
a Some
containing the result of reduceRight(op)
Checks if the given NonEmptySet
contains the same elements in the same order as this NonEmptySet
.
Checks if the given NonEmptySet
contains the same elements in the same order as this NonEmptySet
.
the NonEmptySet
with which to compare
true
, if both this and the given NonEmptySet
contain the same elements
in the same order, false
otherwise.
Checks if the given Every
contains the same elements in the same order as this NonEmptySet
.
Checks if the given Every
contains the same elements in the same order as this NonEmptySet
.
the Every
with which to compare
true
, if both this and the given Every
contain the same elements
in the same order, false
otherwise.
Checks if the given GenIterable
contains the same elements in the same order as this NonEmptySet
.
Checks if the given GenIterable
contains the same elements in the same order as this NonEmptySet
.
the GenIterable
with which to compare
true
, if both this NonEmptySet
and the given GenIterable
contain the same elements
in the same order, false
otherwise.
Computes a prefix scan of the elements of this NonEmptySet
.
Computes a prefix scan of the elements of this NonEmptySet
.
Note: The neutral element z may be applied more than once.
Here are some examples:
NonEmptySet(1, 2, 3).scan(0)(_ + _) == NonEmptySet(0, 1, 3, 6) NonEmptySet(1, 2, 3).scan("z")(_ + _.toString) == NonEmptySet("z", "z1", "z12", "z123")
a type parameter for the binary operator, a supertype of T, and the type of the resulting NonEmptySet
.
a neutral element for the scan operation; may be added to the result an arbitrary number of
times, and must not change the result (e.g., Nil
for Set concatenation,
0 for addition, or 1 for multiplication.)
a binary operator that must be associative
a new NonEmptySet
containing the prefix scan of the elements in this NonEmptySet
Produces a NonEmptySet
containing cumulative results of applying the operator going left to right.
Produces a NonEmptySet
containing cumulative results of applying the operator going left to right.
Here are some examples:
NonEmptySet(1, 2, 3).scanLeft(0)(_ + _) == NonEmptySet(0, 1, 3, 6) NonEmptySet(1, 2, 3).scanLeft("z")(_ + _) == NonEmptySet("z", "z1", "z12", "z123")
the result type of the binary operator and type of the resulting NonEmptySet
the start value.
the binary operator.
a new NonEmptySet
containing the intermediate results of inserting op
between consecutive elements of this NonEmptySet
,
going left to right, with the start value, z
, on the left.
Produces a NonEmptySet
containing cumulative results of applying the operator going right to left.
Produces a NonEmptySet
containing cumulative results of applying the operator going right to left.
Here are some examples:
NonEmptySet(1, 2, 3).scanRight(0)(_ + _) == NonEmptySet(6, 5, 3, 0) NonEmptySet(1, 2, 3).scanRight("z")(_ + _) == NonEmptySet("123z", "23z", "3z", "z")
the result of the binary operator and type of the resulting NonEmptySet
the start value
the binary operator
a new NonEmptySet
containing the intermediate results of inserting op
between consecutive elements of this NonEmptySet
,
going right to left, with the start value, z
, on the right.
The size of this NonEmptySet
.
The size of this NonEmptySet
.
Note: length
and size
yield the same result, which will be >
= 1.
the number of elements in this NonEmptySet
.
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.),
moving the sliding window by a given step
each time.
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.),
moving the sliding window by a given step
each time.
the number of elements per group
the distance between the first elements of successive groups
an iterator producing NonEmptySet
s of size size
, except the last and the only element will be truncated
if there are fewer elements than size
.
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a “sliding window” over them (as opposed to partitioning them, as is done in grouped.)
the number of elements per group
an iterator producing NonEmptySet
s of size size
, except the last and the only element will be truncated
if there are fewer elements than size
.
Returns "NonEmptySet"
, the prefix of this object's toString
representation.
Returns "NonEmptySet"
, the prefix of this object's toString
representation.
the string "NonEmptySet"
The result of summing all the elements of this NonEmptySet
.
The result of summing all the elements of this NonEmptySet
.
This method can be invoked for any NonEmptySet[T]
for which an implicit Numeric[T]
exists.
the sum of all elements
Converts this NonEmptySet
into a collection of type Col
by copying all elements.
Converts this NonEmptySet
into a collection of type Col
by copying all elements.
the collection type to build.
a new collection containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to an array.
Converts this NonEmptySet
to an array.
an array containing all elements of this NonEmptySet
. A ClassTag
must be available for the element type of this NonEmptySet
.
Converts this NonEmptySet
to a mutable buffer.
Converts this NonEmptySet
to a mutable buffer.
a buffer containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to an immutable IndexedSeq
.
Converts this NonEmptySet
to an immutable IndexedSeq
.
an immutable IndexedSeq
containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to an iterable collection.
Converts this NonEmptySet
to an iterable collection.
an Iterable
containing all elements of this NonEmptySet
.
Returns an Iterator
over the elements in this NonEmptySet
.
Returns an Iterator
over the elements in this NonEmptySet
.
an Iterator
containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to a set.
Converts this NonEmptySet
to a set.
a set containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to a map.
Converts this NonEmptySet
to a map.
This method is unavailable unless the elements are members of Tuple2
, each ((K, V))
becoming a key-value pair
in the map. Duplicate keys will be overwritten by later keys.
a map of type immutable.Map[K, V]
containing all key/value pairs of type (K, V)
of this NonEmptySet
.
Converts this NonEmptySet
to an immutable IndexedSeq
.
Converts this NonEmptySet
to an immutable IndexedSeq
.
an immutable IndexedSeq
containing all elements of this NonEmptySet
.
Converts this NonEmptySet
to a stream.
Converts this NonEmptySet
to a stream.
a stream containing all elements of this NonEmptySet
.
Returns a string representation of this NonEmptySet
.
Returns a string representation of this NonEmptySet
.
the string "NonEmptySet"
followed by the result of invoking toString
on
this NonEmptySet
's elements, surrounded by parentheses.
Converts this NonEmptySet
to a Vector
.
Converts this NonEmptySet
to a Vector
.
a Vector
containing all elements of this NonEmptySet
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given GenSeq
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given GenSeq
.
NonEmptySetX
union
ys
is equivalent to NonEmptySetX
++
ys
.
Another way to express this is that NonEmptySetX
union
ys
computes the order-presevring multi-set union
of NonEmptySetX
and ys
. This union
method is hence a counter-part of diff
and intersect
that
also work on multi-sets.
the GenSet
to add.
a new NonEmptySet
that contains all elements of this NonEmptySet
followed by all elements of that
GenSeq
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given NonEmptySet
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given NonEmptySet
.
NonEmptySetX
union
NonEmptySetY
is equivalent to NonEmptySetX
++
NonEmptySetY
.
Another way to express this is that NonEmptySetX
union
NonEmptySetY
computes the order-presevring multi-set union
of NonEmptySetX
and NonEmptySetY
. This union
method is hence a counter-part of diff
and intersect
that
also work on multi-sets.
the NonEmptySet
to add.
a new NonEmptySet
that contains all elements of this NonEmptySet
followed by all elements of that
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given Every
.
Produces a new NonEmptySet
that contains all elements of this NonEmptySet
and also all elements of a given Every
.
NonEmptySetX
union
everyY
is equivalent to NonEmptySetX
++
everyY
.
Another way to express this is that NonEmptySetX
union
everyY
computes the order-presevring multi-set union
of NonEmptySetX
and everyY
. This union
method is hence a counter-part of diff
and intersect
that
also work on multi-sets.
the Every
to add.
a new NonEmptySet
that contains all elements of this NonEmptySet
followed by all elements of that
Every
.
Converts this NonEmptySet
of pairs into two NonEmptySet
s of the first and second half of each pair.
Converts this NonEmptySet
of pairs into two NonEmptySet
s of the first and second half of each pair.
the type of the first half of the element pairs
the type of the second half of the element pairs
an implicit conversion that asserts that the element type of this NonEmptySet
is a pair.
a pair of NonEmptySet
s, containing the first and second half, respectively, of each element pair of this NonEmptySet
.
Converts this NonEmptySet
of triples into three NonEmptySet
s of the first, second, and and third element of each triple.
Converts this NonEmptySet
of triples into three NonEmptySet
s of the first, second, and and third element of each triple.
the type of the first member of the element triples
the type of the second member of the element triples
the type of the third member of the element triples
an implicit conversion that asserts that the element type of this NonEmptySet
is a triple.
a triple of NonEmptySet
s, containing the first, second, and third member, respectively, of each element triple of this NonEmptySet
.
Returns a NonEmptySet
formed from this NonEmptySet
and an iterable collection by combining corresponding
elements in pairs.
Returns a NonEmptySet
formed from this NonEmptySet
and an iterable collection by combining corresponding
elements in pairs. If one of the two collections is shorter than the other, placeholder elements will be used to extend the
shorter collection to the length of the longer.
the Iterable
providing the second half of each result pair
the element to be used to fill up the result if this NonEmptySet
is shorter than that
Iterable
.
the element to be used to fill up the result if that
Iterable
is shorter than this NonEmptySet
.
a new NonEmptySet
containing pairs consisting of corresponding elements of this NonEmptySet
and that
. The
length of the returned collection is the maximum of the lengths of this NonEmptySet
and that
. If this NonEmptySet
is shorter than that
, thisElem
values are used to pad the result. If that
is shorter than this
NonEmptySet
, thatElem
values are used to pad the result.
Zips this NonEmptySet
with its indices.
Zips this NonEmptySet
with its indices.
A new NonEmptySet
containing pairs consisting of all elements of this NonEmptySet
paired with their index. Indices start at 0.
A non-empty Set: an ordered, immutable, non-empty collection of elements with
LinearSeq
performance characteristics.The purpose of
NonEmptySet
is to allow you to express in a type that aSet
is non-empty, thereby eliminating the need for (and potential exception from) a run-time check for non-emptiness. For a non-empty sequence withIndexedSeq
performance, seeEvery
.Constructing
NonEmptySet
sYou can construct a
NonEmptySet
by passing one or more elements to theNonEmptySet.apply
factory method:Alternatively you can cons elements onto the
End
singleton object, similar to making aSet
starting withNil
:Note that although
Nil
is aSet[Nothing]
,End
is not aNonEmptySet[Nothing]
, because no emptyNonEmptySet
exists. (A non-empty Set is a series of connected links; if you have no links, you have no non-empty Set.)Working with
NonEmptySet
sNonEmptySet
does not extend Scala'sSeq
orTraversable
traits because these require that implementations may be empty. For example, if you invoketail
on aSeq
that contains just one element, you'll get an emptySeq
:On the other hand, many useful methods exist on
Seq
that when invoked on a non-emptySeq
are guaranteed to not result in an emptySeq
. For convenience,NonEmptySet
defines a method corresponding to every suchSeq
method. Here are some examples:NonEmptySet
does not currently define any methods corresponding toSeq
methods that could result in an emptySeq
. However, an implicit converison fromNonEmptySet
toSet
is defined in theNonEmptySet
companion object that will be applied if you attempt to call one of the missing methods. As a result, you can invokefilter
on anNonEmptySet
, even thoughfilter
could result in an empty sequence—but the result type will beSet
instead ofNonEmptySet
:You can use
NonEmptySet
s infor
expressions. The result will be anNonEmptySet
unless you use a filter (anif
clause). Because filters are desugared to invocations offilter
, the result type will switch to aSet
at that point. Here are some examples:the type of elements contained in this
NonEmptySet