package stdune
Library
Module
Module type
Parameter
Class
Class type
include module type of struct include ListLabels end
Compare the lengths of two lists. compare_lengths l1 l2
is equivalent to compare (length l1) (length l2)
, except that the computation stops after reaching the end of the shortest list.
Compare the length of a list to an integer. compare_length_with l len
is equivalent to compare (length l) len
, except that the computation stops after at most len
iterations on the list.
Return the n
-th element of the given list. The first element (head of the list) is at position 0. Return None
if the list is too short.
append l0 l1
appends l1
to l0
. Same function as the infix operator @
.
rev_append l1 l2
reverses l1
and concatenates it with l2
. This is equivalent to (
rev
l1) @ l2
.
Concatenate a list of lists. The elements of the argument are all concatenated together (in the same order) to give the result. Not tail-recursive (length of the argument + length of the longest sub-list).
Same as concat
. Not tail-recursive (length of the argument + length of the longest sub-list).
Comparison
Iterators
iter ~f [a1; ...; an]
applies function f
in turn to [a1; ...; an]
. It is equivalent to f a1; f a2; ...; f an
.
Same as iter
, but the function is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.
map ~f [a1; ...; an]
applies function f
to a1, ..., an
, and builds the list [f a1; ...; f an]
with the results returned by f
.
Same as map
, but the function is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.
fold_left_map
is a combination of fold_left
and map
that threads an accumulator through calls to f
.
fold_left ~f ~init [b1; ...; bn]
is f (... (f (f init b1) b2) ...) bn
.
fold_right ~f [a1; ...; an] ~init
is f a1 (f a2 (... (f an init) ...))
. Not tail-recursive.
Iterators on two lists
iter2 ~f [a1; ...; an] [b1; ...; bn]
calls in turn f a1 b1; ...; f an bn
.
map2 ~f [a1; ...; an] [b1; ...; bn]
is [f a1 b1; ...; f an bn]
.
fold_left2 ~f ~init [a1; ...; an] [b1; ...; bn]
is f (... (f (f init a1 b1) a2 b2) ...) an bn
.
fold_right2 ~f [a1; ...; an] [b1; ...; bn] ~init
is f a1 b1 (f a2 b2 (... (f an bn init) ...))
.
List scanning
for_all ~f [a1; ...; an]
checks if all elements of the list satisfy the predicate f
. That is, it returns (f a1) && (f a2) && ... && (f an)
for a non-empty list and true
if the list is empty.
exists ~f [a1; ...; an]
checks if at least one element of the list satisfies the predicate f
. That is, it returns (f a1) || (f a2) || ... || (f an)
for a non-empty list and false
if the list is empty.
Same as exists
, but for a two-argument predicate.
Same as mem
, but uses physical equality instead of structural equality to compare list elements.
List searching
find ~f l
returns the first element of the list l
that satisfies the predicate f
. Returns None
if there is no value that satisfies f
in the list l
.
find_index ~f xs
returns Some i
, where i
is the index of the first element of the list xs
that satisfies f x
, if there is such an element.
It returns None
if there is no such element.
Same as find_map
, but the predicate is applied to the index of the element as first argument (counting from 0), and the element itself as second argument.
filter ~f l
returns all the elements of the list l
that satisfy the predicate f
. The order of the elements in the input list is preserved.
find_all
is another name for filter
.
partition ~f l
returns a pair of lists (l1, l2)
, where l1
is the list of all the elements of l
that satisfy the predicate f
, and l2
is the list of all the elements of l
that do not satisfy f
. The order of the elements in the input list is preserved.
Association lists
assoc_opt a l
returns the value associated with key a
in the list of pairs l
. That is, assoc_opt a [ ...; (a,b); ...] = Some b
if (a,b)
is the leftmost binding of a
in list l
. Returns None
if there is no value associated with a
in the list l
.
Same as assoc
, but uses physical equality instead of structural equality to compare keys.
Same as assoc_opt
, but uses physical equality instead of structural equality to compare keys.
Same as assoc
, but simply return true
if a binding exists, and false
if no bindings exist for the given key.
Same as mem_assoc
, but uses physical equality instead of structural equality to compare keys.
remove_assoc a l
returns the list of pairs l
without the first pair with key a
, if any. Not tail-recursive.
Same as remove_assoc
, but uses physical equality instead of structural equality to compare keys. Not tail-recursive.
Lists of pairs
Transform a list of pairs into a pair of lists: split [(a1,b1); ...; (an,bn)]
is ([a1; ...; an], [b1; ...; bn])
. Not tail-recursive.
Transform a pair of lists into a list of pairs: combine [a1; ...; an] [b1; ...; bn]
is [(a1,b1); ...; (an,bn)]
.
Sorting
Same as sort
or stable_sort
, whichever is faster on typical input.
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 containing all the elements of l1
and l2
. If several elements compare equal, the elements of l1
will be before the elements of l2
. Not tail-recursive (sum of the lengths of the arguments).
Lists and Sequences
val to_seq : 'a list -> 'a Seq.t
Iterate on the list.
val of_seq : 'a Seq.t -> 'a list
Create a list from a sequence.
val is_empty : _ t -> bool
val is_non_empty : _ t -> bool
val filter_partition_map :
'a t ->
f:('a -> ('b, 'c) skip_or_either) ->
'b t * 'c t
val rev_filter_partition_map :
'a t ->
f:('a -> ('b, 'c) skip_or_either) ->
'b t * 'c t
val find : 'a t -> f:('a -> bool) -> 'a option
val findi : 'a t -> f:('a -> bool) -> ('a * int) option
val find_exn : 'a t -> f:('a -> bool) -> 'a
val find_map : 'a t -> f:('a -> 'b option) -> 'b option
val last : 'a t -> 'a option
val destruct_last : 'a t -> ('a list * 'a) option
val sort : 'a t -> compare:('a -> 'a -> Ordering.t) -> 'a t
val stable_sort : 'a t -> compare:('a -> 'a -> Ordering.t) -> 'a t
val sort_uniq : 'a t -> compare:('a -> 'a -> Ordering.t) -> 'a t
val compare : 'a t -> 'a t -> compare:('a -> 'a -> Ordering.t) -> Ordering.t
val assoc : ('a * 'b) t -> 'a -> 'b option
val singleton : 'a -> 'a t
val nth : 'a t -> int -> 'a option
val hd_opt : 'a t -> 'a option
val for_all2 :
'a list ->
'b list ->
f:('a -> 'b -> bool) ->
(bool, [ `Length_mismatch ]) result
val min : 'a list -> f:('a -> 'a -> Ordering.t) -> 'a option
val max : 'a list -> f:('a -> 'a -> Ordering.t) -> 'a option