gen 0.2.3 · OCaml Package

type 'a t

val empty : 'a t

Empty generator, with no elements

val singleton : 'a -> 'a t

One-element generator

val repeat : 'a -> 'a t

Repeat same element endlessly

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

iterate x f is [x; f x; f (f x); f (f (f x)); ...]

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

Dual of fold, with a deconstructing operation. It keeps on unfolding the 'b value into a new 'b, and a 'a which is yielded, until None is returned.

val init : ?limit:int -> (int -> 'a) -> 'a t

Calls the function, starting from 0, on increasing indices. If limit is provided and is a positive int, iteration will stop at the limit (excluded). For instance init ~limit:4 id will yield 0, 1, 2, and 3.

Basic combinators

val is_empty : _ t -> bool

Check whether the gen is empty. Pops an element, if any

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

Fold on the generator, tail-recursively. Consumes the generator.

val reduce : ('a -> 'a -> 'a) -> 'a t -> 'a

Fold on non-empty sequences. Consumes the generator.

raises Invalid_argument
on an empty gen

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

Like fold, but keeping successive values of the accumulator. Consumes the generator.

val unfold_scan : ('b -> 'a -> 'b * 'c) -> 'b -> 'a t -> 'c t

A mix of unfold and scan. The current state is combined with the current element to produce a new state, and an output value of type 'c.

since 0.2.2

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

Iterate on the gen, consumes it.

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

Iterate on elements with their index in the gen, from 0, consuming it.

val length : _ t -> int

Length of an gen (linear time), consuming it

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

Lazy map. No iteration is performed now, the function will be called when the result is traversed.

val append : 'a t -> 'a t -> 'a t

Append the two gens; the result contains the elements of the first, then the elements of the second gen.

val flatten : 'a gen t -> 'a t

Flatten the generator of generators

val flat_map : ('a -> 'b gen) -> 'a t -> 'b t

Monadic bind; each element is transformed to a sub-gen which is then iterated on, before the next element is processed, and so on.

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

Is the given element, member of the gen?

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

Take at most n elements

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

Drop n elements

val nth : int -> 'a t -> 'a

n-th element, or Not_found

raises Not_found
if the generator contains less than n arguments

val take_nth : int -> 'a t -> 'a t

take_nth n g returns every element of g whose index is a multiple of n. For instance take_nth 2 (1--10) |> to_list will return 1;3;5;7;9

val filter : ('a -> bool) -> 'a t -> 'a t

Filter out elements that do not satisfy the predicate.

val take_while : ('a -> bool) -> 'a t -> 'a t

Take elements while they satisfy the predicate

val drop_while : ('a -> bool) -> 'a t -> 'a t

Drop elements while they satisfy the predicate

val filter_map : ('a -> 'b option) -> 'a t -> 'b t

Maps some elements to 'b, drop the other ones

val zip_index : 'a t -> (int * 'a) t

Zip elements with their index in the gen

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

Unzip into two sequences, splitting each pair

val partition : ('a -> bool) -> 'a t -> 'a t * 'a t

partition p l returns the elements that satisfy p, and the elements that do not satisfy p

val for_all : ('a -> bool) -> 'a t -> bool

Is the predicate true for all elements?

val exists : ('a -> bool) -> 'a t -> bool

Is the predicate true for at least one element?

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

Minimum element, according to the given comparison function.

raises Invalid_argument
if the generator is empty

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

Maximum element, see min

raises Invalid_argument
if the generator is empty

val eq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool

Equality of generators.

val lexico : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int

Lexicographic comparison of generators. If a generator is a prefix of the other one, it is considered smaller.

val compare : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int

Synonym for lexico

val find : ('a -> bool) -> 'a t -> 'a option

find p e returns the first element of e to satisfy p, or None.

val sum : int t -> int

Sum of all elements

Multiple iterators

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

Map on the two sequences. Stops once one of them is exhausted.

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

Iterate on the two sequences. Stops once one of them is exhausted.

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

Fold the common prefix of the two iterators

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

Succeeds if all pairs of elements satisfy the predicate. Ignores elements of an iterator if the other runs dry.

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

Succeeds if some pair of elements satisfy the predicate. Ignores elements of an iterator if the other runs dry.

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

Combine common part of the gens (stops when one is exhausted)

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

Zip together the common part of the gens

Complex combinators

val merge : 'a gen t -> 'a t

Pick elements fairly in each sub-generator. The merge of gens e1, e2, ... picks elements in e1, e2, in e3, e1, e2 .... Once a generator is empty, it is skipped; when they are all empty, and none remains in the input, their merge is also empty. For instance, merge [1;3;5] [2;4;6] will be, in disorder, 1;2;3;4;5;6.

val intersection : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> 'a t

Intersection of two sorted sequences. Only elements that occur in both inputs appear in the output

val sorted_merge : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> 'a t

Merge two sorted sequences into a sorted sequence

val sorted_merge_n : ?cmp:('a -> 'a -> int) -> 'a t list -> 'a t

Sorted merge of multiple sorted sequences

val tee : ?n:int -> 'a t -> 'a gen list

Duplicate the gen into n generators (default 2). The generators share the same underlying instance of the gen, so the optimal case is when they are consumed evenly

val round_robin : ?n:int -> 'a t -> 'a gen list

Split the gen into n generators in a fair way. Elements with index = k mod n with go to the k-th gen. n default value is 2.

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

interleave a b yields an element of a, then an element of b, and so on. When a generator is exhausted, this behaves like the other generator.

val intersperse : 'a -> 'a t -> 'a t

Put the separator element between all elements of the given gen

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

Cartesian product, in no predictable order. Works even if some of the arguments are infinite.

val group : ?eq:('a -> 'a -> bool) -> 'a t -> 'a list t

Group equal consecutive elements together.

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

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

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

Sort according to the given comparison function. The gen must be finite.

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

Sort and remove duplicates. The gen must be finite.

val chunks : int -> 'a t -> 'a array t

chunks n e returns a generator of arrays of length n, composed of successive elements of e. The last array may be smaller than n

val permutations : 'a t -> 'a list t

Permutations of the gen.

since 0.2.2

val permutations_heap : 'a t -> 'a array t

Permutations of the gen, using Heap's algorithm.

since 0.2.3

val combinations : int -> 'a t -> 'a list t

Combinations of given length. The ordering of the elements within each combination is unspecified. Example (ignoring ordering): combinations 2 (1--3) |> to_list = [[1;2]; [1;3]; [2;3]]

since 0.2.2

val power_set : 'a t -> 'a list t

All subsets of the gen (in no particular order). The ordering of the elements within each subset is unspecified.

since 0.2.2

Basic conversion functions

val of_list : 'a list -> 'a t

Enumerate elements of the list

val to_list : 'a t -> 'a list

non tail-call trasnformation to list, in the same order

val to_rev_list : 'a t -> 'a list

Tail call conversion to list, in reverse order (more efficient)

val to_array : 'a t -> 'a array

Convert the gen to an array (not very efficient)

val of_array : ?start:int -> ?len:int -> 'a array -> 'a t

Iterate on (a slice of) the given array

val of_string : ?start:int -> ?len:int -> string -> char t

Iterate on bytes of the string

val to_string : char t -> string

Convert into a string

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

Consumes the iterator and writes to the buffer

val rand_int : int -> int t

Random ints in the given range.

val int_range : int -> int -> int t

int_range a b generates integers between a and b, included. a is assumed to be smaller than b.

module Infix : sig ... end

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

Synonym for int_range

val (>>=) : 'a t -> ('a -> 'b gen) -> 'b t

Monadic bind operator

val pp : 
  ?start:string ->
  ?stop:string ->
  ?sep:string ->
  ?horizontal:bool ->
  (Format.formatter -> 'a -> unit) ->
  Format.formatter ->
  'a t ->
  unit

Pretty print the content of the generator on a formatter.

package gen

Basic combinators

Multiple iterators

Complex combinators

Basic conversion functions