in scala
class List

sealed abstract class List [a]
extends java.lang.Object
with scala.Seq[a]
with scala.ScalaObject
A class representing an ordered collection of elements of type a. This class comes with two implementing case classes scala.Nil and scala.:: that implement the abstract members isEmpty, head and tail.
Author:
Martin Odersky and others
Version:
1.0, 16/07/2003
Direct Known Subclasses:
::, Nil

Constructor Summary
def this

Def Summary
def :: [b >: a] (x: b) : scala.List[b]

Add an element x at the beginning of this list. Example:

      1 :: List(2, 3) = List(2, 3).::(1) = List(1, 2, 3)

def ::: [b >: a] (prefix: scala.List[b]) : scala.List[b]

Returns a list resulting from the concatenation of the given list prefix and this list. Example:

      List(1, 2) ::: List(3, 4) = List(3, 4).:::(List(1, 2)) = List(1, 2, 3, 4)

def apply (n: scala.Int) : a
Returns the n-th element of this list. The first element (head of the list) is at position 0.
def break (p: (a) => scala.Boolean) : scala.Tuple2[scala.List[a], scala.List[a]]
Like span but with the predicate inverted.
def count (p: (a) => scala.Boolean) : scala.Int
Count the number of elements in the list which satisfy a predicate.
def diff [b >: a] (that: scala.List[b]) : scala.List[b]
Computes the difference between this list and the given list that.
override def drop (n: scala.Int) : scala.List[a]
Returns the list without its n first elements. If this list has less than n elements, the empty list is returned.
def dropRight (n: scala.Int) : scala.List[a]
Returns the list wihout its rightmost n elements.
override def dropWhile (p: (a) => scala.Boolean) : scala.List[a]
Returns the longest suffix of this list whose first element does not satisfy the predicate p.
def elements : scala.Iterator[a]
Returns the elements in the list as an iterator
override def exists (p: (a) => scala.Boolean) : scala.Boolean
Tests the existence in this list of an element that satisfies the predicate p.
override def filter (p: (a) => scala.Boolean) : scala.List[a]
Returns all the elements of this list that satisfy the predicate p. The order of the elements is preserved.
override def find (p: (a) => scala.Boolean) : scala.Option[a]
Find and return the first element of the list satisfying a predicate, if any.
override def flatMap [b] (f: (a) => scala.Iterable[b]) : scala.List[b]
Applies the given function f to each element of this list, then concatenates the results.
override def foldLeft [b] (z: b)(f: (b, a) => b) : b
Combines the elements of this list together using the binary function f, from left to right, and starting with the value z.
override def foldRight [b] (z: b)(f: (a, b) => b) : b
Combines the elements of this list together using the binary function f, from right to left, and starting with the value z.
override def forall (p: (a) => scala.Boolean) : scala.Boolean
Tests if the predicate p is satisfied by all elements in this list.
override def foreach (f: (a) => scala.Unit) : scala.Unit
Apply the given function f to each element of this list (while respecting the order of the elements).
abstract def head : a
Returns this first element of the list.
def indices : scala.List[scala.Int]
Creates a list with all indices in the list. This is equivalent to a call to List.range(0, xs.length).
def init : scala.List[a]
Returns the list without its last element.
def intersect [b >: a] (that: scala.List[b]) : scala.List[b]
Computes the intersection between this list and the given list that.
abstract override def isEmpty : scala.Boolean
Returns true if the list does not contain any elements.
def last : a
Returns the last element of this list.
def length : scala.Int
Returns the number of elements in the list.
override def map [b] (f: (a) => b) : scala.List[b]
Returns the list resulting from applying the given function f to each element of this list.
def partition (p: (a) => scala.Boolean) : scala.Tuple2[scala.List[a], scala.List[a]]
Partition the list in two sub-lists according to a predicate.
override def reduceLeft [b >: a] (f: (b, b) => b) : b
Combines the elements of this list together using the binary operator op, from left to right
override def reduceRight [b >: a] (f: (b, b) => b) : b
Combines the elements of this list together using the binary operator op, from right to left
def remove (p: (a) => scala.Boolean) : scala.List[a]
Removes all elements of the list which satisfy the predicate p. This is like filter with the predicate inversed.
def removeDuplicates : scala.List[a]
Removes redundant elements from the list. Uses the method == to decide if two elements are identical.
override def reverse : scala.List[a]
A list consisting of all elements of this list in reverse order.
def reverseMap [b] (f: (a) => b) : scala.List[b]
Apply a function to all the elements of the list, and return the reversed list of results. This is equivalent to a call to map followed by a call to reverse, but more efficient.
def reverse_::: [b >: a] (prefix: scala.List[b]) : scala.List[b]
Reverse the given prefix and append the current list to that. This function is equivalent to an application of reverse on the prefix followed by a call to :::, but more efficient (and tail recursive).
def sort (lt: (a, a) => scala.Boolean) : scala.List[a]

Sort the list according to the comparison function <(e1: a, e2: a) => Boolean, which should be true iff e1 is smaller than e2. Example:

      List("Steve", "Tom", "John", "Bob")
        .sort((e1, e2) => (e1 compareTo e2) < 0) =
      List("Bob", "John", "Steve", "Tom")

Note: The current implementation is inefficent for already sorted lists.


def span (p: (a) => scala.Boolean) : scala.Tuple2[scala.List[a], scala.List[a]]
Returns the longest prefix of the list whose elements all satisfy the given predicate, and the rest of the list.
def splitAt (n: scala.Int) : scala.Tuple2[scala.List[a], scala.List[a]]
Split the list at a given point and return the two parts thus created.
override protected def stringPrefix : java.lang.String

abstract def tail : scala.List[a]
Returns this list without its first element.
override def take (n: scala.Int) : scala.List[a]
Returns the n first elements of this list, or else the whole list, if it has less than n elements.
def takeRight (n: scala.Int) : scala.List[a]
Returns the rightmost n elements from this list.
override def takeWhile (p: (a) => scala.Boolean) : scala.List[a]
Returns the longest prefix of this list whose elements satisfy the predicate p.
override def toList : scala.List[a]
Overrides the method in Iterable for efficiency.
def union [b >: a] (that: scala.List[b]) : scala.List[b]
Computes the union of this list and the given list that.
def zip [b] (that: scala.List[b]) : scala.List[scala.Tuple2[a, b]]
Returns a list formed from this list and the specified list that by associating each element of the former with the element at the same position in the latter. If one of the two lists is longer than the other, its remaining elements are ignored.
def zipAll [b, c >: a, d >: b] (that: scala.List[b], thisElem: c, thatElem: d) : scala.List[scala.Tuple2[c, d]]
Returns a list formed from this list and the specified list that by associating each element of the former with the element at the same position in the latter.
def zipWithIndex : scala.List[scala.Tuple2[a, scala.Int]]
Returns a list that pairs each element of this list with its index, counting from 0.
Def inherited from scala.Seq[a]
++ , concat, contains, copyToArray, drop, dropWhile, filter, flatMap, isDefinedAt, isEmpty, lastIndexOf, length, map, reverse, slice, stringPrefix, subseq, super$drop, super$dropWhile, super$filter, super$take, super$takeWhile, take, takeWhile, toArray, toString
Constructor Detail
def this

Def Detail
def :: [b >: a](x: b): scala.List[b]

Add an element x at the beginning of this list. Example:

      1 :: List(2, 3) = List(2, 3).::(1) = List(1, 2, 3)
Parameters:
x - the element to append.
Returns:
the list with x appended at the beginning.

def ::: [b >: a](prefix: scala.List[b]): scala.List[b]

Returns a list resulting from the concatenation of the given list prefix and this list. Example:

      List(1, 2) ::: List(3, 4) = List(3, 4).:::(List(1, 2)) = List(1, 2, 3, 4)
Parameters:
prefix - the list to concatenate at the beginning of this list.
Returns:
the concatenation of the two lists.

def apply (n: scala.Int): a
Returns the n-th element of this list. The first element (head of the list) is at position 0.
Parameters:
n - index of the element to return
Returns:
the element at position n in this list.
Throws:
Predef.NoSuchElementException - if the list is too short.

def break (p: (a) => scala.Boolean): scala.Tuple2[scala.List[a], scala.List[a]]
Like span but with the predicate inverted.

def count (p: (a) => scala.Boolean): scala.Int
Count the number of elements in the list which satisfy a predicate.
Parameters:
p - the predicate for which to count
Returns:
the number of elements satisfying the predicate p.

def diff [b >: a](that: scala.List[b]): scala.List[b]
Computes the difference between this list and the given list that.
Parameters:
that - the list of elements to remove from this list.
Returns:
this list without the elements of the given list that.

override def drop (n: scala.Int): scala.List[a]
Returns the list without its n first elements. If this list has less than n elements, the empty list is returned.
Parameters:
n - the number of elements to drop.
Returns:
the list without its n first elements.

def dropRight (n: scala.Int): scala.List[a]
Returns the list wihout its rightmost n elements.
Parameters:
n - the number of elements to take
Returns:
the suffix of length n of the list

override def dropWhile (p: (a) => scala.Boolean): scala.List[a]
Returns the longest suffix of this list whose first element does not satisfy the predicate p.
Parameters:
p - the test predicate.
Returns:
the longest suffix of the list whose first element does not satisfy the predicate p.

def elements : scala.Iterator[a]
Returns the elements in the list as an iterator
Returns:
an iterator on the list elements.

override def exists (p: (a) => scala.Boolean): scala.Boolean
Tests the existence in this list of an element that satisfies the predicate p.
Parameters:
p - the test predicate.
Returns:
true iff there exists an element in this list that satisfies the predicate p.

override def filter (p: (a) => scala.Boolean): scala.List[a]
Returns all the elements of this list that satisfy the predicate p. The order of the elements is preserved.
Parameters:
p - the predicate used to filter the list.
Returns:
the elements of this list satisfying p.

override def find (p: (a) => scala.Boolean): scala.Option[a]
Find and return the first element of the list satisfying a predicate, if any.
Parameters:
p - the predicate
Returns:
the first element in the list satisfying p, or None if none exists.

override def flatMap [b](f: (a) => scala.Iterable[b]): scala.List[b]
Applies the given function f to each element of this list, then concatenates the results.
Parameters:
f - the function to apply on each element.
Returns:
f(a0) ::: ... ::: f(an) if this list is [a0, ..., an].

override def foldLeft [b](z: b)(f: (b, a) => b): b
Combines the elements of this list together using the binary function f, from left to right, and starting with the value z.
Returns:
f(... (f(f(z, a0), a1) ...), an) if the list is [a0, a1, ..., an].

override def foldRight [b](z: b)(f: (a, b) => b): b
Combines the elements of this list together using the binary function f, from right to left, and starting with the value z.
Returns:
f(a0, f(a1, f(..., f(an, z)...))) if the list is [a0, a1, ..., an].

override def forall (p: (a) => scala.Boolean): scala.Boolean
Tests if the predicate p is satisfied by all elements in this list.
Parameters:
p - the test predicate.
Returns:
true iff all elements of this list satisfy the predicate p.

override def foreach (f: (a) => scala.Unit): scala.Unit
Apply the given function f to each element of this list (while respecting the order of the elements).
Parameters:
f - the treatment to apply to each element.

abstract def head : a
Returns this first element of the list.
Returns:
the first element of this list.
Throws:
Predef.NoSuchElementException - if the list is empty.

def indices : scala.List[scala.Int]
Creates a list with all indices in the list. This is equivalent to a call to List.range(0, xs.length).
Returns:
a list of all indices in the list.

def init : scala.List[a]
Returns the list without its last element.
Returns:
the list without its last element.
Throws:
Predef.UnsupportedOperationException - if the list is empty.

def intersect [b >: a](that: scala.List[b]): scala.List[b]
Computes the intersection between this list and the given list that.
Parameters:
that - the list to intersect.
Returns:
the list of elements contained both in this list and in the given list that.

abstract override def isEmpty : scala.Boolean
Returns true if the list does not contain any elements.
Returns:
true, iff the list is empty.

def last : a
Returns the last element of this list.
Returns:
the last element of the list.
Throws:
Predef.UnsupportedOperationException - if the list is empty.

def length : scala.Int
Returns the number of elements in the list.
Returns:
the number of elements in the list.

override def map [b](f: (a) => b): scala.List[b]
Returns the list resulting from applying the given function f to each element of this list.
Parameters:
f - function to apply to each element.
Returns:
[f(a0), ..., f(an)] if this list is [a0, ..., an].

def partition (p: (a) => scala.Boolean): scala.Tuple2[scala.List[a], scala.List[a]]
Partition the list in two sub-lists according to a predicate.
Parameters:
p - the predicate on which to partition
Returns:
a pair of lists: the list of all elements which satisfy p and the list of all elements which do not. The relative order of the elements in the sub-lists is the same as in the original list.

override def reduceLeft [b >: a](f: (b, b) => b): b
Combines the elements of this list together using the binary operator op, from left to right
Parameters:
op - The operator to apply
Returns:
op(... op(a0,a1), ..., an) if the list has elements a0, a1, ..., an.
Throws:
Predef.UnsupportedOperationException - if the list is empty.

override def reduceRight [b >: a](f: (b, b) => b): b
Combines the elements of this list together using the binary operator op, from right to left
Parameters:
op - The operator to apply
Returns:
a0 op (... op (an-1 op an)...) if the list has elements a0, a1, ..., an.
Throws:
Predef.UnsupportedOperationException - if the list is empty.

def remove (p: (a) => scala.Boolean): scala.List[a]
Removes all elements of the list which satisfy the predicate p. This is like filter with the predicate inversed.
Parameters:
p - the predicate to use to test elements
Returns:
the list without all elements which satisfy p

def removeDuplicates : scala.List[a]
Removes redundant elements from the list. Uses the method == to decide if two elements are identical.
Returns:
the list without doubles.

override def reverse : scala.List[a]
A list consisting of all elements of this list in reverse order.

def reverseMap [b](f: (a) => b): scala.List[b]
Apply a function to all the elements of the list, and return the reversed list of results. This is equivalent to a call to map followed by a call to reverse, but more efficient.
Parameters:
f - the function to apply to each elements.
Returns:
the reversed list of results.

def reverse_::: [b >: a](prefix: scala.List[b]): scala.List[b]
Reverse the given prefix and append the current list to that. This function is equivalent to an application of reverse on the prefix followed by a call to :::, but more efficient (and tail recursive).
Parameters:
prefix - the prefix to reverse and then prepend
Returns:
the concatenation of the reversed prefix and the current list.

def sort (lt: (a, a) => scala.Boolean): scala.List[a]

Sort the list according to the comparison function <(e1: a, e2: a) => Boolean, which should be true iff e1 is smaller than e2. Example:

      List("Steve", "Tom", "John", "Bob")
        .sort((e1, e2) => (e1 compareTo e2) < 0) =
      List("Bob", "John", "Steve", "Tom")

Note: The current implementation is inefficent for already sorted lists.

Parameters:
lt - the comparison function
Returns:
a list sorted according to the comparison function <(e1: a, e2: a) => Boolean.

def span (p: (a) => scala.Boolean): scala.Tuple2[scala.List[a], scala.List[a]]
Returns the longest prefix of the list whose elements all satisfy the given predicate, and the rest of the list.
Parameters:
p - the test predicate
Returns:
a pair consisting of the longest prefix of the list whose elements all satisfy p, and the rest of the list.

def splitAt (n: scala.Int): scala.Tuple2[scala.List[a], scala.List[a]]
Split the list at a given point and return the two parts thus created.
Parameters:
n - the position at which to split
Returns:
a pair of lists composed of the first n elements, and the other elements.

override protected def stringPrefix : java.lang.String

abstract def tail : scala.List[a]
Returns this list without its first element.
Returns:
this list without its first element.
Throws:
Predef.NoSuchElementException - if the list is empty.

override def take (n: scala.Int): scala.List[a]
Returns the n first elements of this list, or else the whole list, if it has less than n elements.
Parameters:
n - the number of elements to take.
Returns:
the n first elements of this list.

def takeRight (n: scala.Int): scala.List[a]
Returns the rightmost n elements from this list.
Parameters:
n - the number of elements to take
Returns:
the suffix of length n of the list

override def takeWhile (p: (a) => scala.Boolean): scala.List[a]
Returns the longest prefix of this list whose elements satisfy the predicate p.
Parameters:
p - the test predicate.
Returns:
the longest prefix of this list whose elements satisfy the predicate p.

override def toList : scala.List[a]
Overrides the method in Iterable for efficiency.
Returns:
the list itself

def union [b >: a](that: scala.List[b]): scala.List[b]
Computes the union of this list and the given list that.
Parameters:
that - the list of elements to add to the list.
Returns:
a list without doubles containing the elements of this list and those of the given list that.

def zip [b](that: scala.List[b]): scala.List[scala.Tuple2[a, b]]
Returns a list formed from this list and the specified list that by associating each element of the former with the element at the same position in the latter. If one of the two lists is longer than the other, its remaining elements are ignored.
Returns:
List({a0,b0}, ..., {amin(m,n),bmin(m,n)}) when List(a0, ..., am) zip List(b0, ..., bn) is invoked.

def zipAll [b, c >: a, d >: b](that: scala.List[b], thisElem: c, thatElem: d): scala.List[scala.Tuple2[c, d]]
Returns a list formed from this list and the specified list that by associating each element of the former with the element at the same position in the latter.
Parameters:
that - list that may have a different length as the self list.
Parameters:
thisElem - element thisElem is used to fill up the resulting list if the self list is shorter than that
Parameters:
thatElem - element thatElem is used to fill up the resulting list if that is shorter than the self list
Returns:
List({a0,b0}, ..., {an,bn}, {elem,bn+1}, ..., {elem,bm}) when [a0, ..., an] zip [b0, ..., bm] is invoked where m > n.

def zipWithIndex : scala.List[scala.Tuple2[a, scala.Int]]
Returns a list that pairs each element of this list with its index, counting from 0.
Returns:
the list List({a0,0}, {a1,1}...) where ai are the elements of this list.