Module CCKList

Continuation List

deprecated

since 2.7, you should use the standard Seq instead. See oseq for similar combinators.

type 'a sequence = ('a -> unit) -> unit
type 'a gen = unit -> 'a option
type 'a equal = 'a -> 'a -> bool
type 'a ord = 'a -> 'a -> int
type 'a printer = Format.formatter -> 'a -> unit

Basics

type +'a t = unit -> [ `Nil | `Cons of 'a * 'a t ]
val nil : 'a t
val empty : 'a t
val cons : 'a -> 'a t -> 'a t
val singleton : 'a -> 'a t
val repeat : ?⁠n:int -> 'a -> 'a t

repeat ~n x repeats x n times then stops. If n is omitted, then x is repeated forever.

since
0.3.3
val cycle : 'a t -> 'a t

Cycle through the iterator infinitely. The iterator shouldn't be empty.

since
0.3.3
val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t

unfold f acc calls f acc and:

  • if f acc = Some (x, acc'), yield x, continue with unfold f acc'.
  • if f acc = None, stops.
since
0.13
val is_empty : 'a t -> bool
val head : 'a t -> 'a option

Head of the list.

since
0.13
val head_exn : 'a t -> 'a

Unsafe version of head.

raises Not_found

if the list is empty.

since
0.13
val tail : 'a t -> 'a t option

Tail of the list.

since
0.13
val tail_exn : 'a t -> 'a t

Unsafe version of tail.

raises Not_found

if the list is empty.

since
0.13
val equal : 'a equal -> 'a t equal

Equality step by step. Eager.

val compare : 'a ord -> 'a t ord

Lexicographic comparison. Eager.

val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a

Fold on values.

val iter : ('a -> unit) -> 'a t -> unit
val iteri : (int -> 'a -> unit) -> 'a t -> unit

Iterate with index (starts at 0).

since
0.13
val length : _ t -> int

Number of elements in the list. Will not terminate if the list if infinite: use (for instance) take to make the list finite if necessary.

val take : int -> 'a t -> 'a t
val take_while : ('a -> bool) -> 'a t -> 'a t
val drop : int -> 'a t -> 'a t
val drop_while : ('a -> bool) -> 'a t -> 'a t
val map : ('a -> 'b) -> 'a t -> 'b t
val mapi : (int -> 'a -> 'b) -> 'a t -> 'b t

Map with index (starts at 0).

since
0.13
val fmap : ('a -> 'b option) -> 'a t -> 'b t
val filter : ('a -> bool) -> 'a t -> 'a t
val append : 'a t -> 'a t -> 'a t
val product_with : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t

Fair product of two (possibly infinite) lists into a new list. Lazy. The first parameter is used to combine each pair of elements.

since
0.3.3
val product : 'a t -> 'b t -> ('a * 'b) t

Specialization of product_with producing tuples.

since
0.3.3
val group : 'a equal -> 'a t -> 'a t t

group eq l groups together consecutive elements that satisfy eq. Lazy. For instance group (=) [1;1;1;2;2;3;3;1] yields [1;1;1]; [2;2]; [3;3]; [1].

since
0.3.3
val uniq : 'a equal -> 'a t -> 'a t

uniq eq l returns l but removes consecutive duplicates. Lazy. In other words, if several values that are equal follow one another, only the first of them is kept.

since
0.3.3
val flat_map : ('a -> 'b t) -> 'a t -> 'b t
val filter_map : ('a -> 'b option) -> 'a t -> 'b t
val flatten : 'a t t -> 'a t
val range : int -> int -> int t
val (--) : int -> int -> int t

a -- b is the range of integers containing a and b (therefore, never empty).

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

a -- b is the integer range from a to b, where b is excluded.

since
0.17

Operations on two Collections

val fold2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc

Fold on two collections at once. Stop at soon as one of them ends.

val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t

Map on two collections at once. Stop as soon as one of the arguments is exhausted.

val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit

Iterate on two collections at once. Stop as soon as one of them ends.

val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
val merge : 'a ord -> 'a t -> 'a t -> 'a t

Merge two sorted iterators into a sorted iterator.

val zip : 'a t -> 'b t -> ('a * 'b) t

Combine elements pairwise. Stop as soon as one of the lists stops.

since
0.13
val unzip : ('a * 'b) t -> 'a t * 'b t

Split each tuple in the list.

since
0.13

Misc

val sort : cmp:'a ord -> 'a t -> 'a t

Eager sort. Require the iterator to be finite. O(n ln(n)) time and space.

since
0.3.3
val sort_uniq : cmp:'a ord -> 'a t -> 'a t

Eager sort that removes duplicate values. Require the iterator to be finite. O(n ln(n)) time and space.

since
0.3.3
val memoize : 'a t -> 'a t

Avoid recomputations by caching intermediate results.

since
0.14

Fair Combinations

val interleave : 'a t -> 'a t -> 'a t

Fair interleaving of both streams.

since
0.13
val fair_flat_map : ('a -> 'b t) -> 'a t -> 'b t

Fair version of flat_map.

since
0.13
val fair_app : ('a -> 'b) t -> 'a t -> 'b t

Fair version of (<*>).

since
0.13

Implementations

since
0.3.3
val return : 'a -> 'a t
val pure : 'a -> 'a t
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
val (>|=) : 'a t -> ('a -> 'b) -> 'b t
val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
val (>>-) : 'a t -> ('a -> 'b t) -> 'b t

Infix version of fair_flat_map.

since
0.13
val (<.>) : ('a -> 'b) t -> 'a t -> 'b t

Infix version of fair_app.

since
0.13

Infix operators

since
0.17
module Infix : sig ... end
module type MONAD = sig ... end
module Traverse : functor (M : MONAD) -> sig ... end

Conversions

val of_list : 'a list -> 'a t
val to_list : 'a t -> 'a list

Gather all values into a list.

val of_array : 'a array -> 'a t

Iterate on the array.

since
0.13
val to_array : 'a t -> 'a array

Convert into array. Iterate twice.

since
0.13
val to_rev_list : 'a t -> 'a list

Convert to a list, in reverse order. More efficient than to_list.

val to_seq : 'a t -> 'a sequence
val to_gen : 'a t -> 'a gen
val of_gen : 'a gen -> 'a t

of_gen g consumes the generator and caches intermediate results.

since
0.13

IO

val pp : ?⁠sep:string -> 'a printer -> 'a t printer

Print the list with the given separator (default ","). Do not print opening/closing delimiters.