
Module Listmodule List:
List operations.
Some functions are flagged as not tailrecursive. A tailrecursive function uses constant stack space, while a nontailrecursive function uses stack space proportional to the length of its list argument, which can be a problem with very long lists. When the function takes several list arguments, an approximate formula giving stack usage (in some unspecified constant unit) is shown in parentheses.
The above considerations can usually be ignored if your lists are not
longer than about 10000 elements. val length :
Return the length (number of elements) of the given list.
val hd :
Return the first element of the given list. Raise
Failure "hd" if the list is empty.val tl :
Return the given list without its first element. Raise
Failure "tl" if the list is empty.val nth :
Return the nth element of the given list.
The first element (head of the list) is at position 0.
Raise
Failure "nth" if the list is too short.val rev :
List reversal.
val append :
Catenate two lists. Same function as the infix operator
@ .
Not tailrecursive (length of the first argument). The @
operator is not tailrecursive either.val rev_append : List.rev_append l1 l2 reverses l1 and concatenates it to l2 .
This is equivalent to List.rev l1 @ l2 , but rev_append is
tailrecursive and more efficient.val concat :
Concatenate a list of lists. The elements of the argument are all
concatenated together (in the same order) to give the result.
Not tailrecursive
(length of the argument + length of the longest sublist).
val flatten :
Same as
concat . Not tailrecursive
(length of the argument + length of the longest sublist).
val iter : List.iter f [a1; ...; an] applies function f in turn to
a1; ...; an . It is equivalent to
begin f a1; f a2; ...; f an; () end .val map : List.map f [a1; ...; an] applies function f to a1, ..., an ,
and builds the list [f a1; ...; f an]
with the results returned by f . Not tailrecursive.val rev_map : List.rev_map f l gives the same result as
List.rev ( List.map f l) , but is tailrecursive and
more efficient.val fold_left : List.fold_left f a [b1; ...; bn] is
f (... (f (f a b1) b2) ...) bn .val fold_right : List.fold_right f [a1; ...; an] b is
f a1 (f a2 (... (f an b) ...)) . Not tailrecursive.
val iter2 : List.iter2 f [a1; ...; an] [b1; ...; bn] calls in turn
f a1 b1; ...; f an bn .
Raise Invalid_argument if the two lists have
different lengths.val map2 : List.map2 f [a1; ...; an] [b1; ...; bn] is
[f a1 b1; ...; f an bn] .
Raise Invalid_argument if the two lists have
different lengths. Not tailrecursive.val rev_map2 : List.rev_map2 f l gives the same result as
List.rev ( List.map2 f l) , but is tailrecursive and
more efficient.val fold_left2 : List.fold_left2 f a [b1; ...; bn] [c1; ...; cn] is
f (... (f (f a b1 c1) b2 c2) ...) bn cn .
Raise Invalid_argument if the two lists have
different lengths.val fold_right2 : List.fold_right2 f [a1; ...; an] [b1; ...; bn] c is
f a1 b1 (f a2 b2 (... (f an bn c) ...)) .
Raise Invalid_argument if the two lists have
different lengths. Not tailrecursive.
val for_all : for_all p [a1; ...; an] checks if all elements of the list
satisfy the predicate p . That is, it returns
(p a1) && (p a2) && ... && (p an) .val exists : exists p [a1; ...; an] checks if at least one element of
the list satisfies the predicate p . That is, it returns
(p a1)  (p a2)  ...  (p an) .val for_all2 :
Same as
List.for_all , but for a twoargument predicate.
Raise Invalid_argument if the two lists have
different lengths.val exists2 :
Same as
List.exists , but for a twoargument predicate.
Raise Invalid_argument if the two lists have
different lengths.val mem : mem a l is true if and only if a is equal
to an element of l .val memq :
Same as
List.mem , but uses physical equality instead of structural
equality to compare list elements.
val find : find p l returns the first element of the list l
that satisfies the predicate p .
Raise Not_found if there is no value that satisfies p in the
list l .val filter : filter p l returns all the elements of the list l
that satisfy the predicate p . The order of the elements
in the input list is preserved.val find_all :
val partition : partition p l returns a pair of lists (l1, l2) , where
l1 is the list of all the elements of l that
satisfy the predicate p , and l2 is the list of all the
elements of l that do not satisfy p .
The order of the elements in the input list is preserved.
val assoc : assoc a l returns the value associated with key a in the list of
pairs l . That is,
assoc a [ ...; (a,b); ...] = b
if (a,b) is the leftmost binding of a in list l .
Raise Not_found if there is no value associated with a in the
list l .val assq :
Same as
List.assoc , but uses physical equality instead of structural
equality to compare keys.val mem_assoc :
Same as
List.assoc , but simply return true if a binding exists,
and false if no bindings exist for the given key.val mem_assq :
Same as
List.mem_assoc , but uses physical equality instead of
structural equality to compare keys.val remove_assoc : remove_assoc a l returns the list of
pairs l without the first pair with key a , if any.
Not tailrecursive.val remove_assq :
Same as
List.remove_assoc , but uses physical equality instead
of structural equality to compare keys. Not tailrecursive.
val split :
Transform a list of pairs into a pair of lists:
split [(a1,b1); ...; (an,bn)] is ([a1; ...; an], [b1; ...; bn]) .
Not tailrecursive.val combine :
Transform a pair of lists into a list of pairs:
combine [a1; ...; an] [b1; ...; bn] is
[(a1,b1); ...; (an,bn)] .
Raise Invalid_argument if the two lists
have different lengths. Not tailrecursive.
val sort :
Sort a list in increasing order according to a comparison
function. The comparison function must return 0 if it arguments
compare as equal, a positive integer if the first is greater,
and a negative integer if the first is smaller (see Array.sort for
a complete specification). For example,
Pervasives.compare is a suitable comparison function.
The resulting list is sorted in increasing order.
List.sort is guaranteed to run in constant heap space
(in addition to the size of the result list) and logarithmic
stack space.
The current implementation uses Merge Sort. It runs in constant
heap space and logarithmic stack space. val stable_sort :
Same as
List.sort , but the sorting algorithm is guaranteed to
be stable (i.e. elements that compare equal are kept in their
original order) .
The current implementation uses Merge Sort. It runs in constant
heap space and logarithmic stack space. val fast_sort :
val merge :
Merge two lists:
Assuming that
l1 and l2 are sorted according to the
comparison function cmp , merge cmp l1 l2 will return a
sorted list containting all the elements of l1 and l2 .
If several elements compare equal, the elements of l1 will be
before the elements of l2 .
Not tailrecursive (sum of the lenghts of the arguments). 