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347 lines
12 KiB
OCaml
347 lines
12 KiB
OCaml
(*
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Copyright (c) 2013, Simon Cruanes
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer. Redistributions in binary
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form must reproduce the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials provided with
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the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 Generators}
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Values of type ['a Gen.t] represent a possibly infinite sequence of values
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of type 'a. One can only iterate once on the sequence, as it is consumed
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by iteration/deconstruction/access. The exception {!EOG} (end of generator)
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is raised when the generator is empty.
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The submodule {!Restart} provides utilities to work with
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{b restartable generators}, that is, functions [unit -> 'a Gen.t] that
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allow to build as many generators from the same source as needed.
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*)
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(** {2 Global type declarations} *)
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exception EOG
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(** End of Generation *)
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type 'a t = unit -> 'a
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(** A generator may be called several times, yielding the next value
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each time. It raises EOG when it reaches the end. *)
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type 'a gen = 'a t
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(** {2 Common signature for transient and restartable generators}
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The signature {!S} abstracts on a type ['a t], where the [t] can be
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the type of transient or restartable generators. Some functions specify
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explicitely that they use ['a gen] (transient generators). *)
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module type S = sig
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type 'a t
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val empty : 'a t
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(** Empty generator, with no elements *)
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val singleton : 'a -> 'a t
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(** One-element generator *)
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val repeat : 'a -> 'a t
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(** Repeat same element endlessly *)
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val iterate : 'a -> ('a -> 'a) -> 'a t
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(** [iterate x f] is [[x; f x; f (f x); f (f (f x)); ...]] *)
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val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t
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(** Dual of {!fold}, with a deconstructing operation. It keeps on
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unfolding the ['b] value into a new ['b], and a ['a] which is yielded,
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until [None] is returned. *)
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(** {2 Basic combinators} *)
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val is_empty : _ t -> bool
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(** Check whether the enum is empty. *)
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val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
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(** Fold on the generator, tail-recursively *)
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val fold2 : ('c -> 'a -> 'b -> 'c) -> 'c -> 'a t -> 'b t -> 'c
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(** Fold on the two enums in parallel. Stops once one of the enums
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is exhausted. *)
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val reduce : ('a -> 'a -> 'a) -> 'a t -> 'a
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(** Fold on non-empty sequences (otherwise raise Invalid_argument) *)
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val scan : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b t
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(** Like {!fold}, but keeping successive values of the accumulator *)
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val iter : ('a -> unit) -> 'a t -> unit
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(** Iterate on the enum *)
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val iteri : (int -> 'a -> unit) -> 'a t -> unit
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(** Iterate on elements with their index in the enum, from 0 *)
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val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit
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(** Iterate on the two sequences. Stops once one of them is exhausted.*)
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val length : _ t -> int
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(** Length of an enum (linear time) *)
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val map : ('a -> 'b) -> 'a t -> 'b t
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(** Lazy map. No iteration is performed now, the function will be called
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when the result is traversed. *)
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val append : 'a t -> 'a t -> 'a t
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(** Append the two enums; the result contains the elements of the first,
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then the elements of the second enum. *)
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val flatten : 'a gen t -> 'a t
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(** Flatten the enumeration of generators *)
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val flatMap : ('a -> 'b gen) -> 'a t -> 'b t
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(** Monadic bind; each element is transformed to a sub-enum
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which is then iterated on, before the next element is processed,
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and so on. *)
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val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
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(** Is the given element, member of the enum? *)
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val take : int -> 'a t -> 'a t
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(** Take at most n elements *)
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val drop : int -> 'a t -> 'a t
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(** Drop n elements *)
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val nth : int -> 'a t -> 'a
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(** n-th element, or Not_found
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@raise Not_found if the generator contains less than [n] arguments *)
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val filter : ('a -> bool) -> 'a t -> 'a t
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(** Filter out elements that do not satisfy the predicate. *)
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val takeWhile : ('a -> bool) -> 'a t -> 'a t
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(** Take elements while they satisfy the predicate *)
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val dropWhile : ('a -> bool) -> 'a t -> 'a t
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(** Drop elements while they satisfy the predicate *)
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val filterMap : ('a -> 'b option) -> 'a t -> 'b t
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(** Maps some elements to 'b, drop the other ones *)
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val zipWith : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
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(** Combine common part of the enums (stops when one is exhausted) *)
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val zip : 'a t -> 'b t -> ('a * 'b) t
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(** Zip together the common part of the enums *)
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val zipIndex : 'a t -> (int * 'a) t
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(** Zip elements with their index in the enum *)
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val unzip : ('a * 'b) t -> 'a t * 'b t
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(** Unzip into two sequences, splitting each pair *)
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val partition : ('a -> bool) -> 'a t -> 'a t * 'a t
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(** [partition p l] returns the elements that satisfy [p],
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and the elements that do not satisfy [p] *)
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val for_all : ('a -> bool) -> 'a t -> bool
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(** Is the predicate true for all elements? *)
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val exists : ('a -> bool) -> 'a t -> bool
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(** Is the predicate true for at least one element? *)
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val for_all2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
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val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
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val min : ?lt:('a -> 'a -> bool) -> 'a t -> 'a
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(** Minimum element, according to the given comparison function *)
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val max : ?lt:('a -> 'a -> bool) -> 'a t -> 'a
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(** Maximum element, see {!min} *)
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val eq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
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(** Equality of generators. *)
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val lexico : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
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(** Lexicographic comparison of generators. If the common prefix is
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the same, the shortest one is considered as smaller than the other. *)
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val compare : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
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(** Synonym for {! lexico} *)
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(** {2 Complex combinators} *)
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val merge : 'a gen t -> 'a t
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(** Pick elements fairly in each sub-generator. The given enum
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must be finite (not its elements, though). The merge of enums
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[e1, e2, ... en] picks one element in [e1], then one element in [e2],
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then in [e3], ..., then in [en], and then starts again at [e1]. Once
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a generator is empty, it is skipped; when they are all empty,
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their merge is also empty.
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For instance, [merge [1;3;5] [2;4;6]] will be [1;2;3;4;5;6]. *)
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val intersection : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> 'a t
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(** Intersection of two sorted sequences. Only elements that occur in both
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inputs appear in the output *)
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val sorted_merge : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> 'a t
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(** Merge two sorted sequences into a sorted sequence *)
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val sorted_merge_n : ?cmp:('a -> 'a -> int) -> 'a gen t -> 'a t
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(** Sorted merge of multiple sorted sequences *)
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val tee : ?n:int -> 'a t -> 'a gen list
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(** Duplicate the enum into [n] generators (default 2). The generators
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share the same underlying instance of the enum, so the optimal case is
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when they are consumed evenly *)
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val round_robin : ?n:int -> 'a t -> 'a gen list
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(** Split the enum into [n] generators in a fair way. Elements with
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[index = k mod n] with go to the k-th enum. [n] default value
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is 2. *)
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val interleave : 'a t -> 'a t -> 'a t
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(** [interleave a b] yields an element of [a], then an element of [b],
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and so on until the end of [a] or [b] is reached. *)
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val intersperse : 'a -> 'a t -> 'a t
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(** Put the separator element between all elements of the given enum *)
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val product : 'a t -> 'b t -> ('a * 'b) t
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(** Cartesian product, in no predictable order. Works even if some of the
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arguments are infinite. *)
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val group : ?eq:('a -> 'a -> bool) -> 'a t -> 'a list t
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(** Group equal consecutive elements together. *)
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val uniq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t
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(** Remove consecutive duplicate elements. Basically this is
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like [fun e -> map List.hd (group e)]. *)
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val sort : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t
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(** Sort according to the given comparison function. The enum must be finite. *)
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val sort_uniq : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t
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(** Sort and remove duplicates. The enum must be finite. *)
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(* TODO later
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val permutations : 'a t -> 'a gen t
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(** Permutations of the enum. Each permutation becomes unavailable once
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the next one is produced. *)
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val combinations : int -> 'a t -> 'a t t
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(** Combinations of given length. *)
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val powerSet : 'a t -> 'a t t
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(** All subsets of the enum (in no particular order) *)
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*)
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(** {2 Basic conversion functions} *)
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val of_list : 'a list -> 'a t
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(** Enumerate elements of the list *)
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val to_list : 'a t -> 'a list
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(** non tail-call trasnformation to list, in the same order *)
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val to_rev_list : 'a t -> 'a list
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(** Tail call conversion to list, in reverse order (more efficient) *)
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val to_array : 'a t -> 'a array
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(** Convert the enum to an array (not very efficient) *)
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val of_array : ?start:int -> ?len:int -> 'a array -> 'a t
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(** Iterate on (a slice of) the given array *)
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val rand_int : int -> int t
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(** Random ints in the given range. *)
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val int_range : int -> int -> int t
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(** [int_range a b] enumerates integers between [a] and [b], included. [a]
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is assumed to be smaller than [b]. *)
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module Infix : sig
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val (--) : int -> int -> int t
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(** Synonym for {! int_range} *)
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val (>>=) : 'a t -> ('a -> 'b gen) -> 'b t
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(** Monadic bind operator *)
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end
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val (--) : int -> int -> int t
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(** Synonym for {! int_range} *)
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val (>>=) : 'a t -> ('a -> 'b gen) -> 'b t
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(** Monadic bind operator *)
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val pp : ?start:string -> ?stop:string -> ?sep:string -> ?horizontal:bool ->
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(Format.formatter -> 'a -> unit) -> Format.formatter -> 'a t -> unit
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(** Pretty print the content of the generator on a formatter. *)
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end
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(** {2 Transient generators} *)
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val get : 'a t -> 'a
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(** Get the next value
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@raise EOG if there is no next value *)
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val next : 'a t -> 'a
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(** Synonym for {!get} *)
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val get_safe : 'a t -> 'a option
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(** Get the next value, or return None *)
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val junk : 'a t -> unit
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(** Drop the next value, discarding it.
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@raise EOG if there is no next value *)
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val repeatedly : (unit -> 'a) -> 'a t
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(** Call the same function an infinite number of times (useful for instance
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if the function is a random generator). *)
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include S with type 'a t := 'a gen
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(** Operations on {b transient} generators *)
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(** {2 Restartable generators} *)
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module Restart : sig
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type 'a t = unit -> 'a gen
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type 'a restartable = 'a t
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include S with type 'a t := 'a restartable
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val cycle : 'a t -> 'a t
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(** Cycle through the enum, endlessly. The enum must not be empty. *)
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val lift : ('a gen -> 'b) -> 'a t -> 'b
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val lift2 : ('a gen -> 'b gen -> 'c) -> 'a t -> 'b t -> 'c
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end
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(** {2 Utils} *)
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val persistent : 'a t -> 'a Restart.t
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(** Store content of the transient generator in memory, to be able to iterate
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on it several times later. If possible, consider using combinators
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from {!Restart} directly instead. *)
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val start : 'a Restart.t -> 'a t
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(** Create a new transient generator.
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[start gen] is the same as [gen ()] but is included for readability. *)
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