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lists(3)		   Erlang Module Definition		      lists(3)

NAME
       lists - List processing functions.

DESCRIPTION
       This module contains functions for list processing.

       Unless  otherwise  stated, all functions	assume that position numbering
       starts at 1. That is, the first element of a list is at position	1.

       Two terms T1 and	T2 compare equal if T1 == T2 evaluates to  true.  They
       match if	T1 =:= T2 evaluates to true.

       Whenever	 an ordering function F	is expected as argument, it is assumed
       that the	following properties hold of F for all x, y, and z:

	 * If x	F y and	y F x, then x =	y (F is	antisymmetric).

	 * If x	F y and	y F z, then x F	z (F is	transitive).

	 * x F y or y F	x (F is	total).

       An example of a typical ordering	function is less  than	or  equal  to:
       =_/2.

EXPORTS
       all(Pred, List) -> boolean()

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List =	[T]
		 T = term()

	      Returns true if Pred(Elem) returns true for all elements Elem in
	      List, otherwise false.

       any(Pred, List) -> boolean()

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List =	[T]
		 T = term()

	      Returns true if Pred(Elem) returns true for at least one element
	      Elem in List.

       append(ListOfLists) -> List1

	      Types:

		 ListOfLists = [List]
		 List =	List1 =	[T]
		 T = term()

	      Returns  a  list	in  which all the sublists of ListOfLists have
	      been appended.

	      Example:

	      >	lists:append([[1, 2, 3], [a, b], [4, 5,	6]]).
	      [1,2,3,a,b,4,5,6]

       append(List1, List2) -> List3

	      Types:

		 List1 = List2 = List3 = [T]
		 T = term()

	      Returns a	new list List3,	which is made  from  the  elements  of
	      List1 followed by	the elements of	List2.

	      Example:

	      >	lists:append("abc", "def").
	      "abcdef"

	      lists:append(A, B) is equivalent to A ++ B.

       concat(Things) -> string()

	      Types:

		 Things	= [Thing]
		 Thing = atom()	| integer() | float() |	string()

	      Concatenates  the	text representation of the elements of Things.
	      The elements of  Things  can  be	atoms,	integers,  floats,  or
	      strings.

	      Example:

	      >	lists:concat([doc, '/',	file, '.', 3]).
	      "doc/file.3"

       delete(Elem, List1) -> List2

	      Types:

		 Elem =	T
		 List1 = List2 = [T]
		 T = term()

	      Returns a	copy of	List1 where the	first element matching Elem is
	      deleted, if there	is such	an element.

       droplast(List) -> InitList

	      Types:

		 List =	[T, ...]
		 InitList = [T]
		 T = term()

	      Drops the	last element of	a List.	The list is to	be  non-empty,
	      otherwise	the function crashes with a function_clause.

       dropwhile(Pred, List1) -> List2

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List1 = List2 = [T]
		 T = term()

	      Drops elements Elem from List1 while Pred(Elem) returns true and
	      returns the remaining list.

       duplicate(N, Elem) -> List

	      Types:

		 N = integer() >= 0
		 Elem =	T
		 List =	[T]
		 T = term()

	      Returns a	list containing	N copies of term Elem.

	      Example:

	      >	lists:duplicate(5, xx).
	      [xx,xx,xx,xx,xx]

       filter(Pred, List1) -> List2

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List1 = List2 = [T]
		 T = term()

	      List2 is a  list	of  all	 elements  Elem	 in  List1  for	 which
	      Pred(Elem) returns true.

       filtermap(Fun, List1) ->	List2

	      Types:

		 Fun = fun((Elem) -> boolean() | {true,	Value})
		 List1 = [Elem]
		 List2 = [Elem | Value]
		 Elem =	Value =	term()

	      Calls Fun(Elem) on successive elements Elem of List1. Fun/1 must
	      return either a Boolean or a tuple {true,	Value}.	 The  function
	      returns  the list	of elements for	which Fun returns a new	value,
	      where a value of true is synonymous with {true, Elem}.

	      That is, filtermap behaves as if it had been defined as follows:

	      filtermap(Fun, List1) ->
		  lists:foldr(fun(Elem,	Acc) ->
				     case Fun(Elem) of
					 false -> Acc;
					 true -> [Elem|Acc];
					 {true,Value} -> [Value|Acc]
				     end
			      end, [], List1).

	      Example:

	      >	lists:filtermap(fun(X) -> case X rem 2 of 0 -> {true, X	div 2};	_ -> false end end, [1,2,3,4,5]).
	      [1,2]

       flatlength(DeepList) -> integer() >= 0

	      Types:

		 DeepList = [term() | DeepList]

	      Equivalent to length(flatten(DeepList)), but more	efficient.

       flatmap(Fun, List1) -> List2

	      Types:

		 Fun = fun((A) -> [B])
		 List1 = [A]
		 List2 = [B]
		 A = B = term()

	      Takes a function from As to lists	 of  Bs,  and  a  list	of  As
	      (List1)  and  produces  a	list of	Bs by applying the function to
	      every element in List1 and appending the resulting lists.

	      That is, flatmap behaves as if it	had been defined as follows:

	      flatmap(Fun, List1) ->
		  append(map(Fun, List1)).

	      Example:

	      >	lists:flatmap(fun(X)->[X,X] end, [a,b,c]).
	      [a,a,b,b,c,c]

       flatten(DeepList) -> List

	      Types:

		 DeepList = [term() | DeepList]
		 List =	[term()]

	      Returns a	flattened version of DeepList.

       flatten(DeepList, Tail) -> List

	      Types:

		 DeepList = [term() | DeepList]
		 Tail =	List = [term()]

	      Returns a	flattened version of DeepList with tail	Tail appended.

       foldl(Fun, Acc0,	List) -> Acc1

	      Types:

		 Fun = fun((Elem :: T, AccIn) -> AccOut)
		 Acc0 =	Acc1 = AccIn = AccOut =	term()
		 List =	[T]
		 T = term()

	      Calls Fun(Elem, AccIn) on	successive elements A of List,	start-
	      ing  with	 AccIn	==  Acc0. Fun/2	must return a new accumulator,
	      which is passed to the next call.	The function returns the final
	      value of the accumulator.	Acc0 is	returned if the	list is	empty.

	      Example:

	      >	lists:foldl(fun(X, Sum)	-> X + Sum end,	0, [1,2,3,4,5]).
	      15
	      >	lists:foldl(fun(X, Prod) -> X *	Prod end, 1, [1,2,3,4,5]).
	      120

       foldr(Fun, Acc0,	List) -> Acc1

	      Types:

		 Fun = fun((Elem :: T, AccIn) -> AccOut)
		 Acc0 =	Acc1 = AccIn = AccOut =	term()
		 List =	[T]
		 T = term()

	      Like foldl/3, but	the list is traversed from right to left.

	      Example:

	      >	P = fun(A, AccIn) -> io:format("~p ", [A]), AccIn end.
	      #Fun<erl_eval.12.2225172>
	      >	lists:foldl(P, void, [1,2,3]).
	      1	2 3 void
	      >	lists:foldr(P, void, [1,2,3]).
	      3	2 1 void

	      foldl/3 is tail recursive	and is usually preferred to foldr/3.

       join(Sep, List1)	-> List2

	      Types:

		 Sep = T
		 List1 = List2 = [T]
		 T = term()

	      Inserts  Sep between each	element	in List1. Has no effect	on the
	      empty list and on	a singleton list. For example:

	      >	lists:join(x, [a,b,c]).
	      [a,x,b,x,c]
	      >	lists:join(x, [a]).
	      [a]
	      >	lists:join(x, []).
	      []

       foreach(Fun, List) -> ok

	      Types:

		 Fun = fun((Elem :: T) -> term())
		 List =	[T]
		 T = term()

	      Calls Fun(Elem) for each element Elem in List. This function  is
	      used for its side	effects	and the	evaluation order is defined to
	      be the same as the order of the elements in the list.

       keydelete(Key, N, TupleList1) ->	TupleList2

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [Tuple]
		 Tuple = tuple()

	      Returns a	copy of	TupleList1 where the first occurrence of a tu-
	      ple whose	Nth element compares equal to Key is deleted, if there
	      is such a	tuple.

       keyfind(Key, N, TupleList) -> Tuple | false

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList = [Tuple]
		 Tuple = tuple()

	      Searches the list	of tuples TupleList for	a tuple	whose Nth ele-
	      ment  compares  equal  to	 Key. Returns Tuple if such a tuple is
	      found, otherwise false.

       keymap(Fun, N, TupleList1) -> TupleList2

	      Types:

		 Fun = fun((Term1 :: term()) ->	Term2 :: term())
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [Tuple]
		 Tuple = tuple()

	      Returns a	list of	tuples where, for each	tuple  in  TupleList1,
	      the  Nth	element	 Term1 of the tuple has	been replaced with the
	      result of	calling	Fun(Term1).

	      Examples:

	      >	Fun = fun(Atom)	-> atom_to_list(Atom) end.
	      #Fun<erl_eval.6.10732646>
	      2> lists:keymap(Fun, 2, [{name,jane,22},{name,lizzie,20},{name,lydia,15}]).
	      [{name,"jane",22},{name,"lizzie",20},{name,"lydia",15}]

       keymember(Key, N, TupleList) -> boolean()

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList = [Tuple]
		 Tuple = tuple()

	      Returns true if there is a tuple in TupleList whose Nth  element
	      compares equal to	Key, otherwise false.

       keymerge(N, TupleList1, TupleList2) -> TupleList3

	      Types:

		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = [T1]
		 TupleList2 = [T2]
		 TupleList3 = [T1 | T2]
		 T1 = T2 = Tuple
		 Tuple = tuple()

	      Returns  the  sorted  list  formed by merging TupleList1 and Tu-
	      pleList2.	The merge is performed on the Nth element of each  tu-
	      ple.  Both  TupleList1  and TupleList2 must be key-sorted	before
	      evaluating this function.	When two tuples	compare	equal, the tu-
	      ple from TupleList1 is picked before the tuple from TupleList2.

       keyreplace(Key, N, TupleList1, NewTuple)	-> TupleList2

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [Tuple]
		 NewTuple = Tuple
		 Tuple = tuple()

	      Returns  a  copy of TupleList1 where the first occurrence	of a T
	      tuple whose Nth element compares equal to	Key is	replaced  with
	      NewTuple,	if there is such a tuple T.

       keysearch(Key, N, TupleList) -> {value, Tuple} |	false

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList = [Tuple]
		 Tuple = tuple()

	      Searches the list	of tuples TupleList for	a tuple	whose Nth ele-
	      ment compares equal to Key. Returns {value, Tuple} if such a tu-
	      ple is found, otherwise false.

	  Note:
	      This  function  is retained for backward compatibility. Function
	      keyfind/3	is usually more	convenient.

       keysort(N, TupleList1) -> TupleList2

	      Types:

		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [Tuple]
		 Tuple = tuple()

	      Returns a	list  containing  the  sorted  elements	 of  list  Tu-
	      pleList1.	Sorting	is performed on	the Nth	element	of the tuples.
	      The sort is stable.

       keystore(Key, N,	TupleList1, NewTuple) -> TupleList2

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = [Tuple]
		 TupleList2 = [Tuple, ...]
		 NewTuple = Tuple
		 Tuple = tuple()

	      Returns a	copy of	TupleList1 where the first occurrence of a tu-
	      ple  T  whose Nth	element	compares equal to Key is replaced with
	      NewTuple,	if there is such a tuple T. If there is	no such	 tuple
	      T,  a  copy  of TupleList1 where [NewTuple] has been appended to
	      the end is returned.

       keytake(Key, N, TupleList1) -> {value, Tuple, TupleList2} | false

	      Types:

		 Key = term()
		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [tuple()]
		 Tuple = tuple()

	      Searches the list	of tuples TupleList1 for a tuple whose Nth el-
	      ement  compares equal to Key. Returns {value, Tuple, TupleList2}
	      if such a	tuple is found,	otherwise false. TupleList2 is a  copy
	      of  TupleList1  where the	first occurrence of Tuple has been re-
	      moved.

       last(List) -> Last

	      Types:

		 List =	[T, ...]
		 Last =	T
		 T = term()

	      Returns the last element in List.

       map(Fun,	List1) -> List2

	      Types:

		 Fun = fun((A) -> B)
		 List1 = [A]
		 List2 = [B]
		 A = B = term()

	      Takes a function from As to Bs, and a list of As and produces  a
	      list  of	Bs  by	applying  the function to every	element	in the
	      list. This function is used to obtain  the  return  values.  The
	      evaluation order depends on the implementation.

       mapfoldl(Fun, Acc0, List1) -> {List2, Acc1}

	      Types:

		 Fun = fun((A, AccIn) -> {B, AccOut})
		 Acc0 =	Acc1 = AccIn = AccOut =	term()
		 List1 = [A]
		 List2 = [B]
		 A = B = term()

	      Combines the operations of map/2 and foldl/3 into	one pass.

	      Example:

	      Summing the elements in a	list and double	them at	the same time:

	      >	lists:mapfoldl(fun(X, Sum) -> {2*X, X+Sum} end,
	      0, [1,2,3,4,5]).
	      {[2,4,6,8,10],15}

       mapfoldr(Fun, Acc0, List1) -> {List2, Acc1}

	      Types:

		 Fun = fun((A, AccIn) -> {B, AccOut})
		 Acc0 =	Acc1 = AccIn = AccOut =	term()
		 List1 = [A]
		 List2 = [B]
		 A = B = term()

	      Combines the operations of map/2 and foldr/3 into	one pass.

       max(List) -> Max

	      Types:

		 List =	[T, ...]
		 Max = T
		 T = term()

	      Returns  the first element of List that compares greater than or
	      equal to all other elements of List.

       member(Elem, List) -> boolean()

	      Types:

		 Elem =	T
		 List =	[T]
		 T = term()

	      Returns true if Elem matches some	 element  of  List,  otherwise
	      false.

       merge(ListOfLists) -> List1

	      Types:

		 ListOfLists = [List]
		 List =	List1 =	[T]
		 T = term()

	      Returns  the  sorted  list formed	by merging all the sublists of
	      ListOfLists. All sublists	must be	sorted before evaluating  this
	      function.	 When two elements compare equal, the element from the
	      sublist with the lowest position in ListOfLists is picked	before
	      the other	element.

       merge(List1, List2) -> List3

	      Types:

		 List1 = [X]
		 List2 = [Y]
		 List3 = [X | Y]
		 X = Y = term()

	      Returns  the sorted list formed by merging List1 and List2. Both
	      List1 and	List2 must be sorted before evaluating this  function.
	      When  two	 elements  compare  equal,  the	 element from List1 is
	      picked before the	element	from List2.

       merge(Fun, List1, List2)	-> List3

	      Types:

		 Fun = fun((A, B) -> boolean())
		 List1 = [A]
		 List2 = [B]
		 List3 = [A | B]
		 A = B = term()

	      Returns the sorted list formed by	merging	List1 and List2.  Both
	      List1  and  List2	must be	sorted according to the	ordering func-
	      tion Fun before evaluating this function.	Fun(A, B) is to	return
	      true if A	compares less than or equal to B in the	ordering, oth-
	      erwise false. When two elements compare equal, the element  from
	      List1 is picked before the element from List2.

       merge3(List1, List2, List3) -> List4

	      Types:

		 List1 = [X]
		 List2 = [Y]
		 List3 = [Z]
		 List4 = [X | Y	| Z]
		 X = Y = Z = term()

	      Returns  the  sorted  list  formed  by merging List1, List2, and
	      List3. All of List1, List2, and  List3  must  be	sorted	before
	      evaluating  this	function. When two elements compare equal, the
	      element from List1, if there is such an element, is  picked  be-
	      fore  the	 other	element,  otherwise  the element from List2 is
	      picked before the	element	from List3.

       min(List) -> Min

	      Types:

		 List =	[T, ...]
		 Min = T
		 T = term()

	      Returns the first	element	of List	that  compares	less  than  or
	      equal to all other elements of List.

       nth(N, List) -> Elem

	      Types:

		 N = integer() >= 1
		   1..length(List)
		 List =	[T, ...]
		 Elem =	T
		 T = term()

	      Returns the Nth element of List.

	      Example:

	      >	lists:nth(3, [a, b, c, d, e]).
	      c

       nthtail(N, List)	-> Tail

	      Types:

		 N = integer() >= 0
		   0..length(List)
		 List =	[T, ...]
		 Tail =	[T]
		 T = term()

	      Returns  the  Nth	 tail  of  List,  that is, the sublist of List
	      starting at N+1 and continuing up	to the end of the list.

	      Example

	      >	lists:nthtail(3, [a, b,	c, d, e]).
	      [d,e]
	      >	tl(tl(tl([a, b,	c, d, e]))).
	      [d,e]
	      >	lists:nthtail(0, [a, b,	c, d, e]).
	      [a,b,c,d,e]
	      >	lists:nthtail(5, [a, b,	c, d, e]).
	      []

       partition(Pred, List) ->	{Satisfying, NotSatisfying}

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List =	Satisfying = NotSatisfying = [T]
		 T = term()

	      Partitions List into two lists, where the	 first	list  contains
	      all  elements  for which Pred(Elem) returns true,	and the	second
	      list contains all	elements for which Pred(Elem) returns false.

	      Examples:

	      >	lists:partition(fun(A) -> A rem	2 == 1 end, [1,2,3,4,5,6,7]).
	      {[1,3,5,7],[2,4,6]}
	      >	lists:partition(fun(A) -> is_atom(A) end, [a,b,1,c,d,2,3,4,e]).
	      {[a,b,c,d,e],[1,2,3,4]}

	      For a different way to partition a list, see splitwith/2.

       prefix(List1, List2) -> boolean()

	      Types:

		 List1 = List2 = [T]
		 T = term()

	      Returns true if List1 is a prefix	of List2, otherwise false.

       reverse(List1) -> List2

	      Types:

		 List1 = List2 = [T]
		 T = term()

	      Returns a	list with the elements in List1	in reverse order.

       reverse(List1, Tail) -> List2

	      Types:

		 List1 = [T]
		 Tail =	term()
		 List2 = [T]
		 T = term()

	      Returns a	list with the elements in List1	in reverse order, with
	      tail Tail	appended.

	      Example:

	      >	lists:reverse([1, 2, 3,	4], [a,	b, c]).
	      [4,3,2,1,a,b,c]

       search(Pred, List) -> {value, Value} | false

	      Types:

		 Pred =	fun((T)	-> boolean())
		 List =	[T]
		 Value = T

	      If  there	is a Value in List such	that Pred(Value) returns true,
	      returns {value, Value} for the first such	Value,	otherwise  re-
	      turns false.

       seq(From, To) ->	Seq

       seq(From, To, Incr) -> Seq

	      Types:

		 From =	To = Incr = integer()
		 Seq = [integer()]

	      Returns  a  sequence  of integers	that starts with From and con-
	      tains the	successive results of adding Incr to the previous ele-
	      ment,  until  To is reached or passed (in	the latter case, To is
	      not an element of	the sequence). Incr defaults to	1.

	      Failures:

		* If To	_ From - Incr and Incr _ 0.

		* If To	_ From - Incr and Incr _ 0.

		* If Incr =:= 0	and From =/= To.

	      The following equalities hold for	all sequences:

	      length(lists:seq(From, To)) =:= To - From	+ 1
	      length(lists:seq(From, To, Incr))	=:= (To	- From + Incr) div Incr

	      Examples:

	      >	lists:seq(1, 10).
	      [1,2,3,4,5,6,7,8,9,10]
	      >	lists:seq(1, 20, 3).
	      [1,4,7,10,13,16,19]
	      >	lists:seq(1, 0,	1).
	      []
	      >	lists:seq(10, 6, 4).
	      []
	      >	lists:seq(1, 1,	0).
	      [1]

       sort(List1) -> List2

	      Types:

		 List1 = List2 = [T]
		 T = term()

	      Returns a	list containing	the sorted elements of List1.

       sort(Fun, List1)	-> List2

	      Types:

		 Fun = fun((A :: T, B :: T) -> boolean())
		 List1 = List2 = [T]
		 T = term()

	      Returns a	list containing	the sorted elements of List1,  accord-
	      ing to the ordering function Fun.	Fun(A, B) is to	return true if
	      A	compares less than or equal to B in  the  ordering,  otherwise
	      false.

       split(N,	List1) -> {List2, List3}

	      Types:

		 N = integer() >= 0
		   0..length(List1)
		 List1 = List2 = List3 = [T]
		 T = term()

	      Splits  List1  into  List2 and List3. List2 contains the first N
	      elements and List3 the remaining elements	(the Nth tail).

       splitwith(Pred, List) ->	{List1,	List2}

	      Types:

		 Pred =	fun((T)	-> boolean())
		 List =	List1 =	List2 =	[T]
		 T = term()

	      Partitions List into two lists according	to  Pred.  splitwith/2
	      behaves as if it is defined as follows:

	      splitwith(Pred, List) ->
		  {takewhile(Pred, List), dropwhile(Pred, List)}.

	      Examples:

	      >	lists:splitwith(fun(A) -> A rem	2 == 1 end, [1,2,3,4,5,6,7]).
	      {[1],[2,3,4,5,6,7]}
	      >	lists:splitwith(fun(A) -> is_atom(A) end, [a,b,1,c,d,2,3,4,e]).
	      {[a,b],[1,c,d,2,3,4,e]}

	      For a different way to partition a list, see partition/2.

       sublist(List1, Len) -> List2

	      Types:

		 List1 = List2 = [T]
		 Len = integer() >= 0
		 T = term()

	      Returns  the  sublist  of	 List1 starting	at position 1 and with
	      (maximum)	Len elements. It is not	an error for Len to exceed the
	      length of	the list, in that case the whole list is returned.

       sublist(List1, Start, Len) -> List2

	      Types:

		 List1 = List2 = [T]
		 Start = integer() >= 1
		   1..(length(List1)+1)
		 Len = integer() >= 0
		 T = term()

	      Returns  the  sublist of List1 starting at Start and with	(maxi-
	      mum) Len elements. It is not an error for	 Start+Len  to	exceed
	      the length of the	list.

	      Examples:

	      >	lists:sublist([1,2,3,4], 2, 2).
	      [2,3]
	      >	lists:sublist([1,2,3,4], 2, 5).
	      [2,3,4]
	      >	lists:sublist([1,2,3,4], 5, 2).
	      []

       subtract(List1, List2) -> List3

	      Types:

		 List1 = List2 = List3 = [T]
		 T = term()

	      Returns  a  new list List3 that is a copy	of List1, subjected to
	      the following procedure: for each	element	in  List2,  its	 first
	      occurrence in List1 is deleted.

	      Example:

	      >	lists:subtract("123212", "212").
	      "312".

	      lists:subtract(A,	B) is equivalent to A -- B.

       suffix(List1, List2) -> boolean()

	      Types:

		 List1 = List2 = [T]
		 T = term()

	      Returns true if List1 is a suffix	of List2, otherwise false.

       sum(List) -> number()

	      Types:

		 List =	[number()]

	      Returns the sum of the elements in List.

       takewhile(Pred, List1) -> List2

	      Types:

		 Pred =	fun((Elem :: T)	-> boolean())
		 List1 = List2 = [T]
		 T = term()

	      Takes  elements  Elem  from List1	while Pred(Elem) returns true,
	      that is, the function returns the	longest	prefix of the list for
	      which all	elements satisfy the predicate.

       ukeymerge(N, TupleList1,	TupleList2) -> TupleList3

	      Types:

		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = [T1]
		 TupleList2 = [T2]
		 TupleList3 = [T1 | T2]
		 T1 = T2 = Tuple
		 Tuple = tuple()

	      Returns  the  sorted  list  formed by merging TupleList1 and Tu-
	      pleList2.	The merge is performed on the Nth element of each  tu-
	      ple.  Both  TupleList1 and TupleList2 must be key-sorted without
	      duplicates before	evaluating this	function. When two tuples com-
	      pare equal, the tuple from TupleList1 is picked and the one from
	      TupleList2 is deleted.

       ukeysort(N, TupleList1) -> TupleList2

	      Types:

		 N = integer() >= 1
		   1..tuple_size(Tuple)
		 TupleList1 = TupleList2 = [Tuple]
		 Tuple = tuple()

	      Returns a	list containing	the sorted elements of list TupleList1
	      where  all  except the first tuple of the	tuples comparing equal
	      have been	deleted. Sorting is performed on the  Nth  element  of
	      the tuples.

       umerge(ListOfLists) -> List1

	      Types:

		 ListOfLists = [List]
		 List =	List1 =	[T]
		 T = term()

	      Returns  the  sorted  list formed	by merging all the sublists of
	      ListOfLists. All sublists	must be	sorted and contain  no	dupli-
	      cates before evaluating this function. When two elements compare
	      equal, the element from the sublist with the lowest position  in
	      ListOfLists is picked and	the other is deleted.

       umerge(List1, List2) -> List3

	      Types:

		 List1 = [X]
		 List2 = [Y]
		 List3 = [X | Y]
		 X = Y = term()

	      Returns  the sorted list formed by merging List1 and List2. Both
	      List1 and	List2 must be sorted and contain no duplicates	before
	      evaluating  this	function. When two elements compare equal, the
	      element from List1 is picked and the one from List2 is deleted.

       umerge(Fun, List1, List2) -> List3

	      Types:

		 Fun = fun((A, B) -> boolean())
		 List1 = [A]
		 List2 = [B]
		 List3 = [A | B]
		 A = B = term()

	      Returns the sorted list formed by	merging	List1 and List2.  Both
	      List1  and  List2	must be	sorted according to the	ordering func-
	      tion Fun and contain no duplicates before	evaluating this	 func-
	      tion.  Fun(A,  B)	 is  to	return true if A compares less than or
	      equal to B in the	ordering, otherwise false. When	 two  elements
	      compare equal, the element from List1 is picked and the one from
	      List2 is deleted.

       umerge3(List1, List2, List3) -> List4

	      Types:

		 List1 = [X]
		 List2 = [Y]
		 List3 = [Z]
		 List4 = [X | Y	| Z]
		 X = Y = Z = term()

	      Returns the sorted list formed  by  merging  List1,  List2,  and
	      List3. All of List1, List2, and List3 must be sorted and contain
	      no duplicates before evaluating this function. When two elements
	      compare equal, the element from List1 is picked if there is such
	      an element, otherwise the	element	from List2 is picked, and  the
	      other is deleted.

       unzip(List1) -> {List2, List3}

	      Types:

		 List1 = [{A, B}]
		 List2 = [A]
		 List3 = [B]
		 A = B = term()

	      "Unzips"	a  list	 of two-tuples into two	lists, where the first
	      list contains the	first element of each tuple,  and  the	second
	      list contains the	second element of each tuple.

       unzip3(List1) ->	{List2,	List3, List4}

	      Types:

		 List1 = [{A, B, C}]
		 List2 = [A]
		 List3 = [B]
		 List4 = [C]
		 A = B = C = term()

	      "Unzips"	a  list	 of  three-tuples  into	three lists, where the
	      first list contains the first element of each tuple, the	second
	      list  contains  the  second element of each tuple, and the third
	      list contains the	third element of each tuple.

       usort(List1) -> List2

	      Types:

		 List1 = List2 = [T]
		 T = term()

	      Returns a	list containing	the sorted elements of List1 where all
	      except  the  first  element of the elements comparing equal have
	      been deleted.

       usort(Fun, List1) -> List2

	      Types:

		 Fun = fun((T, T) -> boolean())
		 List1 = List2 = [T]
		 T = term()

	      Returns a	list containing	the sorted elements of List1 where all
	      except the first element of the elements comparing equal accord-
	      ing to the ordering function Fun have been deleted. Fun(A, B) is
	      to  return true if A compares less than or equal to B in the or-
	      dering, otherwise	false.

       zip(List1, List2) -> List3

	      Types:

		 List1 = [A]
		 List2 = [B]
		 List3 = [{A, B}]
		 A = B = term()

	      "Zips" two lists of equal	length into one	 list  of  two-tuples,
	      where  the  first	 element of each tuple is taken	from the first
	      list and the second element is taken from	the corresponding ele-
	      ment in the second list.

       zip3(List1, List2, List3) -> List4

	      Types:

		 List1 = [A]
		 List2 = [B]
		 List3 = [C]
		 List4 = [{A, B, C}]
		 A = B = C = term()

	      "Zips"  three  lists  of equal length into one list of three-tu-
	      ples, where the first element of each tuple is  taken  from  the
	      first  list,  the	second element is taken	from the corresponding
	      element in the second list, and the third	element	is taken  from
	      the corresponding	element	in the third list.

       zipwith(Combine,	List1, List2) -> List3

	      Types:

		 Combine = fun((X, Y) -> T)
		 List1 = [X]
		 List2 = [Y]
		 List3 = [T]
		 X = Y = T = term()

	      Combines	the  elements  of  two	lists of equal length into one
	      list. For	each pair X, Y of list elements	from  the  two	lists,
	      the element in the result	list is	Combine(X, Y).

	      zipwith(fun(X,  Y)  -_ {X,Y} end,	List1, List2) is equivalent to
	      zip(List1, List2).

	      Example:

	      >	lists:zipwith(fun(X, Y)	-> X+Y end, [1,2,3], [4,5,6]).
	      [5,7,9]

       zipwith3(Combine, List1,	List2, List3) -> List4

	      Types:

		 Combine = fun((X, Y, Z) -> T)
		 List1 = [X]
		 List2 = [Y]
		 List3 = [Z]
		 List4 = [T]
		 X = Y = Z = T = term()

	      Combines the elements of three lists of equal  length  into  one
	      list.  For  each	triple X, Y, Z of list elements	from the three
	      lists, the element in the	result list is Combine(X, Y, Z).

	      zipwith3(fun(X, Y, Z) -_ {X,Y,Z} end, List1,  List2,  List3)  is
	      equivalent to zip3(List1,	List2, List3).

	      Examples:

	      >	lists:zipwith3(fun(X, Y, Z) -> X+Y+Z end, [1,2,3], [4,5,6], [7,8,9]).
	      [12,15,18]
	      >	lists:zipwith3(fun(X, Y, Z) -> [X,Y,Z] end, [a,b,c], [x,y,z], [1,2,3]).
	      [[a,x,1],[b,y,2],[c,z,3]]

Ericsson AB			  stdlib 3.8			      lists(3)

NAME | DESCRIPTION | EXPORTS

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