Module `IterLabels`Source

Simple and Efficient Iterators

Version of Iterator with labels

since 0.5.5

Sourcetype +'a t = ('a -> unit) -> unit

An iterator of values of type 'a. If you give it a function 'a -> unit it will be applied to every element of the iterator successively.

Sourcetype +'a iter = 'a t

NOTE Type ('a, 'b) t2 = ('a -> 'b -> unit) -> unit has been removed and subsumed by ('a * 'b) t

since 1.0

Sourcetype 'a equal = 'a -> 'a -> bool

Sourcetype 'a hash = 'a -> int

Creation

Sourceval from_iter : (('a -> unit) -> unit) -> 'a t

Build an iterator from a iter function

Sourceval from_labelled_iter : (f:('a -> unit) -> unit) -> 'a t

Build an iterator from a labelled iter function

since 1.2

Sourceval from_fun : (unit -> 'a option) -> 'a t

Call the function repeatedly until it returns None. This iterator is transient, use persistent if needed!

Sourceval empty : 'a t

Empty iterator. It contains no element.

Sourceval singleton : 'a -> 'a t

Singleton iterator, with exactly one element.

Sourceval doubleton : 'a -> 'a -> 'a t

Iterator with exactly two elements

Sourceval init : f:(int -> 'a) -> 'a t

init f is the infinite iterator f 0; f 1; f 2; ….

since 0.9

Sourceval cons : 'a -> 'a t -> 'a t

cons x l yields x, then yields from l. Same as append (singleton x) l

Sourceval snoc : 'a t -> 'a -> 'a t

Same as cons but yields the element after iterating on l

Sourceval return : 'a -> 'a t

Synonym to singleton

Sourceval pure : 'a -> 'a t

Synonym to singleton

Sourceval repeat : 'a -> 'a t

Infinite iterator of the same element. You may want to look at take and the likes if you iterate on it.

Sourceval iterate : ('a -> 'a) -> 'a -> 'a t

iterate f x is the infinite iterator x, f(x), f(f(x)), ...

Sourceval forever : (unit -> 'b) -> 'b t

Iterator that calls the given function to produce elements. The iterator may be transient (depending on the function), and definitely is infinite. You may want to use take and persistent.

Sourceval cycle : 'a t -> 'a t

Cycle forever through the given iterator. Assume the given iterator can be traversed any amount of times (not transient). This yields an infinite iterator, you should use something like take not to loop forever.

Consumption

Sourceval iter : f:('a -> unit) -> 'a t -> unit

Consume the iterator, passing all its arguments to the function. Basically iter f seq is just seq f.

Sourceval iteri : f:(int -> 'a -> unit) -> 'a t -> unit

Iterate on elements and their index in the iterator

Sourceval fold : f:('a -> 'b -> 'a) -> init:'a -> 'b t -> 'a

Fold over elements of the iterator, consuming it

Sourceval foldi : f:('a -> int -> 'b -> 'a) -> init:'a -> 'b t -> 'a

Fold over elements of the iterator and their index, consuming it

Sourceval fold_map : f:('acc -> 'a -> 'acc * 'b) -> init:'acc -> 'a t -> 'b t

fold_map f acc l is like map, but it carries some state as in fold. The state is not returned, it is just used to thread some information to the map function.

since 0.9

Source

val fold_filter_map : 
  f:('acc -> 'a -> 'acc * 'b option) ->
  init:'acc ->
  'a t ->
  'b t

fold_filter_map f acc l is a fold_map-like function, but the function can choose to skip an element by retuning None.

since 0.9

Sourceval map : f:('a -> 'b) -> 'a t -> 'b t

Map objects of the iterator into other elements, lazily

Sourceval mapi : f:(int -> 'a -> 'b) -> 'a t -> 'b t

Map objects, along with their index in the iterator

Sourceval map_by_2 : f:('a -> 'a -> 'a) -> 'a t -> 'a t

Map objects two by two. lazily. The last element is kept in the iterator if the count is odd.

since 0.7

Sourceval for_all : f:('a -> bool) -> 'a t -> bool

Do all elements satisfy the predicate?

Sourceval exists : f:('a -> bool) -> 'a t -> bool

Exists there some element satisfying the predicate?

Sourceval mem : ?eq:('a -> 'a -> bool) -> x:'a -> 'a t -> bool

Is the value a member of the iterator?

parameter eq
the equality predicate to use (default (=))

since 0.5

Sourceval find : ('a -> 'b option) -> 'a t -> 'b option

Find the first element on which the function doesn't return None

since 0.5

Sourceval find_map : f:('a -> 'b option) -> 'a t -> 'b option

Alias to find

since 0.10

Sourceval findi : f:(int -> 'a -> 'b option) -> 'a t -> 'b option

Indexed version of find

since 0.9

Sourceval find_mapi : f:(int -> 'a -> 'b option) -> 'a t -> 'b option

Alias to findi

since 0.10

Sourceval find_pred : f:('a -> bool) -> 'a t -> 'a option

find_pred p l finds the first element of l that satisfies p, or returns None if no element satisfies p

since 0.9

Sourceval find_pred_exn : f:('a -> bool) -> 'a t -> 'a

Unsafe version of find_pred

raises Not_found
if no such element is found

since 0.9

Sourceval length : 'a t -> int

How long is the iterator? Forces the iterator.

Sourceval is_empty : 'a t -> bool

Is the iterator empty? Forces the iterator.

Transformation

Sourceval filter : f:('a -> bool) -> 'a t -> 'a t

Filter on elements of the iterator

Sourceval append : 'a t -> 'a t -> 'a t

Append two iterators. Iterating on the result is like iterating on the first, then on the second.

Sourceval append_l : 'a t list -> 'a t

Append iterators. Iterating on the result is like iterating on the each iterator of the list in order.

since 0.11

Sourceval concat : 'a t t -> 'a t

Concatenate an iterator of iterators into one iterator.

Sourceval flatten : 'a t t -> 'a t

Alias for concat

Sourceval flat_map : f:('a -> 'b t) -> 'a t -> 'b t

Alias to flatMap with a more explicit name

Sourceval flat_map_l : f:('a -> 'b list) -> 'a t -> 'b t

Convenience function combining flat_map and of_list

since 0.9

Sourceval seq_list : 'a t list -> 'a list t

seq_list l returns all the ways to pick one element in each sub-iterator in l. Assumes the sub-iterators can be iterated on several times.

since 0.11

Sourceval seq_list_map : f:('a -> 'b t) -> 'a list -> 'b list t

seq_list_map f l maps f over every element of l, then calls seq_list

since 0.11

Sourceval filter_map : f:('a -> 'b option) -> 'a t -> 'b t

Map and only keep non-None elements Formerly fmap

Sourceval filter_mapi : f:(int -> 'a -> 'b option) -> 'a t -> 'b t

Map with indices, and only keep non-None elements

since 0.11

Sourceval filter_count : f:('a -> bool) -> 'a t -> int

Count how many elements satisfy the given predicate

since 1.0

Sourceval intersperse : x:'a -> 'a t -> 'a t

Insert the single element between every element of the iterator

Sourceval keep_some : 'a option t -> 'a t

filter_some l retains only elements of the form Some x. Same as filter_map (fun x->x)

since 1.0

Sourceval keep_ok : ('a, _) Result.result t -> 'a t

keep_ok l retains only elements of the form Ok x.

since 1.0

Sourceval keep_error : (_, 'e) Result.result t -> 'e t

keep_error l retains only elements of the form Error x.

since 1.0

Caching

Sourceval persistent : 'a t -> 'a t

Iterate on the iterator, storing elements in an efficient internal structure.. The resulting iterator can be iterated on as many times as needed. Note: calling persistent on an already persistent iterator will still make a new copy of the iterator!

Sourceval persistent_lazy : 'a t -> 'a t

Lazy version of persistent. When calling persistent_lazy s, a new iterator s' is immediately returned (without actually consuming s) in constant time; the first time s' is iterated on, it also consumes s and caches its content into a inner data structure that will back s' for future iterations.

warning: on the first traversal of s', if the traversal is interrupted prematurely (take, etc.) then s' will not be memorized, and the next call to s' will traverse s again.

Misc

Sourceval sort : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t

Sort the iterator. Eager, O(n) ram and O(n ln(n)) time. It iterates on elements of the argument iterator immediately, before it sorts them.

Sourceval sort_uniq : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t

Sort the iterator and remove duplicates. Eager, same as sort

Sourceval sorted : ?cmp:('a -> 'a -> int) -> 'a t -> bool

Checks whether the iterator is sorted. Eager, same as sort.

since 0.9

Sourceval group_succ_by : ?eq:('a -> 'a -> bool) -> 'a t -> 'a list t

Group equal consecutive elements. Formerly synonym to group.

since 0.6

Sourceval group_by : ?hash:('a -> int) -> ?eq:('a -> 'a -> bool) -> 'a t -> 'a list t

Group equal elements, disregarding their order of appearance. The result iterator is traversable as many times as required. precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.6

Sourceval count : ?hash:('a -> int) -> ?eq:('a -> 'a -> bool) -> 'a t -> ('a * int) t

Map each distinct element to its number of occurrences in the whole seq. Similar to group_by seq |> map (fun l->List.hd l, List.length l)

since 0.10

Sourceval uniq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t

Remove consecutive duplicate elements. Basically this is like fun seq -> map List.hd (group seq).

Sourceval product : 'a t -> 'b t -> ('a * 'b) t

Cartesian product of the iterators. When calling product a b, the caller MUST ensure that b can be traversed as many times as required (several times), possibly by calling persistent on it beforehand.

Sourceval diagonal_l : 'a list -> ('a * 'a) t

All pairs of distinct positions of the list. diagonal l will return the iterator of all List.nth i l, List.nth j l if i < j.

since 0.9

Sourceval diagonal : 'a t -> ('a * 'a) t

All pairs of distinct positions of the iterator. Iterates only once on the iterator, which must be finite.

since 0.9

Sourceval join : join_row:('a -> 'b -> 'c option) -> 'a t -> 'b t -> 'c t

join ~join_row a b combines every element of a with every element of b using join_row. If join_row returns None, then the two elements do not combine. Assume that b allows for multiple iterations.

Source

val join_by : 
  ?eq:'key equal ->
  ?hash:'key hash ->
  ('a -> 'key) ->
  ('b -> 'key) ->
  merge:('key -> 'a -> 'b -> 'c option) ->
  'a t ->
  'b t ->
  'c t

join key1 key2 ~merge is a binary operation that takes two iterators a and b, projects their elements resp. with key1 and key2, and combine values (x,y) from (a,b) with the same key using merge. If merge returns None, the combination of values is discarded. precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.10

Source

val join_all_by : 
  ?eq:'key equal ->
  ?hash:'key hash ->
  ('a -> 'key) ->
  ('b -> 'key) ->
  merge:('key -> 'a list -> 'b list -> 'c option) ->
  'a t ->
  'b t ->
  'c t

join_all_by key1 key2 ~merge is a binary operation that takes two iterators a and b, projects their elements resp. with key1 and key2, and, for each key k occurring in at least one of them:

compute the list l1 of elements of a that map to k
compute the list l2 of elements of b that map to k
call merge k l1 l2. If merge returns None, the combination of values is discarded, otherwise it returns Some c and c is inserted in the result.

since 0.10

Source

val group_join_by : 
  ?eq:'a equal ->
  ?hash:'a hash ->
  ('b -> 'a) ->
  'a t ->
  'b t ->
  ('a * 'b list) t

group_join_by key2 associates to every element x of the first iterator, all the elements y of the second iterator such that eq x (key y). Elements of the first iterators without corresponding values in the second one are mapped to [] precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.10

Sourceval inter : ?eq:'a equal -> ?hash:'a hash -> 'a t -> 'a t -> 'a t

Intersection of two collections. Each element will occur at most once in the result. Eager. precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.10

Sourceval union : ?eq:'a equal -> ?hash:'a hash -> 'a t -> 'a t -> 'a t

Union of two collections. Each element will occur at most once in the result. Eager. precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.10

Sourceval diff : ?eq:'a equal -> ?hash:'a hash -> 'a t -> 'a t -> 'a t

Set difference. Eager.

since 0.10

Sourceval subset : ?eq:'a equal -> ?hash:'a hash -> 'a t -> 'a t -> bool

subset a b returns true if all elements of a belong to b. Eager. precondition: for any x and y, if eq x y then hash x=hash y must hold.

since 0.10

Sourceval unfoldr : ('b -> ('a * 'b) option) -> 'b -> 'a t

unfoldr f b will apply f to b. If it yields Some (x,b') then x is returned and unfoldr recurses with b'.

Sourceval scan : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b t

Iterator of intermediate results

Sourceval max : ?lt:('a -> 'a -> bool) -> 'a t -> 'a option

Max element of the iterator, using the given comparison function.

returns
None if the iterator is empty, Some m where m is the maximal element otherwise

Sourceval max_exn : ?lt:('a -> 'a -> bool) -> 'a t -> 'a

Unsafe version of max

raises Not_found
if the iterator is empty

since 0.10

Sourceval min : ?lt:('a -> 'a -> bool) -> 'a t -> 'a option

Min element of the iterator, using the given comparison function. see max for more details.

Sourceval min_exn : ?lt:('a -> 'a -> bool) -> 'a t -> 'a

Unsafe version of min

raises Not_found
if the iterator is empty

since 0.10

Sourceval sum : int t -> int

Sum of elements

since 0.11

Sourceval sumf : float t -> float

Sum of elements, using Kahan summation

since 0.11

Sourceval head : 'a t -> 'a option

First element, if any, otherwise None

since 0.5.1

Sourceval head_exn : 'a t -> 'a

First element, if any, fails

raises Invalid_argument
if the iterator is empty

since 0.5.1

Sourceval take : int -> 'a t -> 'a t

Take at most n elements from the iterator. Works on infinite iterators.

Sourceval take_while : f:('a -> bool) -> 'a t -> 'a t

Take elements while they satisfy the predicate, then stops iterating. Will work on an infinite iterator s if the predicate is false for at least one element of s.

Source

val fold_while : 
  f:('a -> 'b -> 'a * [ `Stop | `Continue ]) ->
  init:'a ->
  'b t ->
  'a

Folds over elements of the iterator, stopping early if the accumulator returns ('a, `Stop)

since 0.5.5

Sourceval drop : int -> 'a t -> 'a t

Drop the n first elements of the iterator. Lazy.

Sourceval drop_while : f:('a -> bool) -> 'a t -> 'a t

Predicate version of drop

Sourceval rev : 'a t -> 'a t

Reverse the iterator. O(n) memory and time, needs the iterator to be finite. The result is persistent and does not depend on the input being repeatable.

Sourceval zip_i : 'a t -> (int * 'a) t

Zip elements of the iterator with their index in the iterator.

since 1.0 Changed type to just give an iterator of pairs

Sourceval fold2 : f:('c -> 'a -> 'b -> 'c) -> init:'c -> ('a * 'b) t -> 'c

Sourceval iter2 : f:('a -> 'b -> unit) -> ('a * 'b) t -> unit

Sourceval map2 : f:('a -> 'b -> 'c) -> ('a * 'b) t -> 'c t

Source

val map2_2 : 
  f:('a -> 'b -> 'c) ->
  ('a -> 'b -> 'd) ->
  ('a * 'b) t ->
  ('c * 'd) t

map2_2 f g seq2 maps each x, y of seq2 into f x y, g x y

Data structures converters

Sourceval to_list : 'a t -> 'a list

Convert the iterator into a list. Preserves order of elements. This function is tail-recursive, but consumes 2*n memory. If order doesn't matter to you, consider to_rev_list.

Sourceval to_rev_list : 'a t -> 'a list

Get the list of the reversed iterator (more efficient than to_list)

Sourceval of_list : 'a list -> 'a t

Sourceval on_list : ('a t -> 'b t) -> 'a list -> 'b list

on_list f l is equivalent to to_list @@ f @@ of_list l.

since 0.5.2

Sourceval pair_with_idx : 'a t -> (int * 'a) t

Similar to zip_i but returns a normal iterator of tuples

since 0.11

Sourceval to_opt : 'a t -> 'a option

Alias to head

since 0.5.1

Sourceval to_array : 'a t -> 'a array

Convert to an array. Currently not very efficient because an intermediate list is used.

Sourceval of_array : 'a array -> 'a t

Sourceval of_array_i : 'a array -> (int * 'a) t

Elements of the array, with their index

Sourceval array_slice : 'a array -> int -> int -> 'a t

array_slice a i j Iterator of elements whose indexes range from i to j

Sourceval of_opt : 'a option -> 'a t

Iterate on 0 or 1 values.

since 0.5.1

Sourceval of_stream : 'a Stream.t -> 'a t

Iterator of elements of a stream (usable only once)

Sourceval to_stream : 'a t -> 'a Stream.t

Convert to a stream. linear in memory and time (a copy is made in memory)

Sourceval to_stack : 'a Stack.t -> 'a t -> unit

Push elements of the iterator on the stack

Sourceval of_stack : 'a Stack.t -> 'a t

Iterator of elements of the stack (same order as Stack.iter)

Sourceval to_queue : 'a Queue.t -> 'a t -> unit

Push elements of the iterator into the queue

Sourceval of_queue : 'a Queue.t -> 'a t

Iterator of elements contained in the queue, FIFO order

Sourceval hashtbl_add : ('a, 'b) Hashtbl.t -> ('a * 'b) t -> unit

Add elements of the iterator to the hashtable, with Hashtbl.add

Sourceval hashtbl_replace : ('a, 'b) Hashtbl.t -> ('a * 'b) t -> unit

Add elements of the iterator to the hashtable, with Hashtbl.replace (erases conflicting bindings)

Sourceval to_hashtbl : ('a * 'b) t -> ('a, 'b) Hashtbl.t

Build a hashtable from an iterator of key/value pairs

Sourceval of_hashtbl : ('a, 'b) Hashtbl.t -> ('a * 'b) t

Iterator of key/value pairs from the hashtable

Sourceval hashtbl_keys : ('a, 'b) Hashtbl.t -> 'a t

Sourceval hashtbl_values : ('a, 'b) Hashtbl.t -> 'b t

Sourceval of_str : string -> char t

Sourceval to_str : char t -> string

Sourceval concat_str : string t -> string

Concatenate strings together, eagerly. Also see intersperse to add a separator.

since 0.5

Sourceexception OneShotSequence

Raised when the user tries to iterate several times on a transient iterator

Sourceval of_in_channel : in_channel -> char t

Iterates on characters of the input (can block when one iterates over the iterator). If you need to iterate several times on this iterator, use persistent.

raises OneShotIterator
when used more than once.

Sourceval to_buffer : char t -> Buffer.t -> unit

Copy content of the iterator into the buffer

Sourceval int_range : start:int -> stop:int -> int t

Iterator on integers in start...stop by steps 1. Also see (--) for an infix version.

Sourceval int_range_dec : start:int -> stop:int -> int t

Iterator on decreasing integers in stop...start by steps -1. See (--^) for an infix version

Sourceval int_range_by : step:int -> start:int -> stop:int -> int t

int_range_by ~step ~start:i ~stop:j is the range starting at i, including j, where the difference between successive elements is step. use a negative step for a decreasing iterator.

since 0.9

raises Invalid_argument
if step=0

Sourceval bools : bool t

Iterates on true and false

since 0.9

Sourceval of_set : (module Set.S with type elt = 'a and type t = 'b) -> 'b -> 'a t

Convert the given set to an iterator. The set module must be provided.

Sourceval to_set : (module Set.S with type elt = 'a and type t = 'b) -> 'a t -> 'b

Convert the iterator to a set, given the proper set module

Sourcetype 'a gen = unit -> 'a option

Sourcetype 'a klist = unit -> [ `Nil | `Cons of 'a * 'a klist ]

Sourceval of_gen : 'a gen -> 'a t

Traverse eagerly the generator and build an iterator from it

Sourceval to_gen : 'a t -> 'a gen

Make the iterator persistent (O(n)) and then iterate on it. Eager.

Sourceval of_klist : 'a klist -> 'a t

Iterate on the lazy list

Sourceval to_klist : 'a t -> 'a klist

Make the iterator persistent and then iterate on it. Eager.

Sets

Sourcemodule Set : sig ... end

Maps

Sourcemodule Map : sig ... end

Random iterators

Sourceval random_int : int -> int t

Infinite iterator of random integers between 0 and the given higher bound (see Random.int)

Sourceval random_bool : bool t

Infinite iterator of random bool values

Sourceval random_float : float -> float t

Sourceval random_array : 'a array -> 'a t

Iterator of choices of an element in the array

Sourceval random_list : 'a list -> 'a t

Infinite iterator of random elements of the list. Basically the same as random_array.

Sourceval shuffle : 'a t -> 'a t

shuffle seq returns a perfect shuffle of seq. Uses O(length seq) memory and time. Eager.

since 0.7

Sourceval shuffle_buffer : n:int -> 'a t -> 'a t

shuffle_buffer n seq returns an iterator of element of seq in random order. The shuffling is not uniform. Uses O(n) memory.

The first n elements of the iterator are consumed immediately. The rest is consumed lazily.

since 0.7

Sampling

Sourceval sample : n:int -> 'a t -> 'a array

sample n seq returns k samples of seq, with uniform probability. It will consume the iterator and use O(n) memory.

It returns an array of size min (length seq) n.

since 0.7

Infix functions

Sourcemodule Infix : sig ... end

include module type of Infix

Sourceval (--) : int -> int -> int t

a -- b is the range of integers from a to b, both included, in increasing order. It will therefore be empty if a > b.

Sourceval (--^) : int -> int -> int t

a --^ b is the range of integers from b to a, both included, in decreasing order (starts from a). It will therefore be empty if a < b.

Sourceval (>>=) : 'a t -> ('a -> 'b t) -> 'b t

Monadic bind (infix version of flat_map

since 0.5

Sourceval (>|=) : 'a t -> ('a -> 'b) -> 'b t

Infix version of map

since 0.5

Sourceval (<*>) : ('a -> 'b) t -> 'a t -> 'b t

Applicative operator (product+application)

since 0.5

Sourceval (<+>) : 'a t -> 'a t -> 'a t

Concatenation of iterators

since 0.5

Pretty printing

Source

val pp_seq : 
  ?sep:string ->
  (Format.formatter -> 'a -> unit) ->
  Format.formatter ->
  'a t ->
  unit

Pretty print an iterator of 'a, using the given pretty printer to print each elements. An optional separator string can be provided.

Source

val pp_buf : 
  ?sep:string ->
  (Buffer.t -> 'a -> unit) ->
  Buffer.t ->
  'a t ->
  unit

Print into a buffer

Sourceval to_string : ?sep:string -> ('a -> string) -> 'a t -> string

Print into a string

Basic IO

Very basic interface to manipulate files as iterator of chunks/lines. The iterators take care of opening and closing files properly; every time one iterates over an iterator, the file is opened/closed again.

Example: copy a file "a" into file "b", removing blank lines:

  Iterator.(IO.lines_of "a" |> filter (fun l-> l<> "") |> IO.write_lines "b");;

By chunks of 4096 bytes:

  Iterator.IO.(chunks_of ~size:4096 "a" |> write_to "b");;

Read the lines of a file into a list:

  Iterator.IO.lines "a" |> Iterator.to_list

since 0.5.1

Sourcemodule IO : sig ... end

Install

Dune Dependency

Authors

Maintainers

Sources

doc/iter/IterLabels/index.html

Module `IterLabels`Source

Simple and Efficient Iterators

Creation

Consumption

Transformation

Caching

Misc

Data structures converters

Sets

Maps

Random iterators

Sampling

Infix functions

Pretty printing

Basic IO

package iter

Install

Dune Dependency

Authors

Maintainers

Sources

doc/iter/IterLabels/index.html

Module IterLabelsSource

Simple and Efficient Iterators

Creation

Consumption

Transformation

Caching

Misc

Data structures converters

Sets

Maps

Random iterators

Sampling

Infix functions

Pretty printing

Basic IO

Module `IterLabels`Source