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package gen
Generators
Values of type 'a Gen.t represent a possibly infinite sequence of values of type 'a. One can only iterate once on the sequence, as it is consumed by iteration/deconstruction/access. None is returned when the generator is exhausted.
The submodule Restart provides utilities to work with restartable generators, that is, functions unit -> 'a Gen.t that allow to build as many generators from the same source as needed.
Global type declarations
A generator may be called several times, yielding the next value each time. It returns None when no elements remain
type 'a gen = 'a tmodule type S = Gen_intf.STransient generators
val get : 'a t -> 'a optionGet the next value
val get_exn : 'a t -> 'aGet the next value, or fails
val junk : 'a t -> unitDrop the next value, discarding it.
val repeatedly : (unit -> 'a) -> 'a tCall the same function an infinite number of times (useful for instance if the function is a random generator).
Operations on transient generators
include S with type 'a t := 'a gen
val empty : 'a genEmpty generator, with no elements
val singleton : 'a -> 'a genOne-element generator
val repeat : 'a -> 'a genRepeat same element endlessly
val iterate : 'a -> ('a -> 'a) -> 'a geniterate x f is [x; f x; f (f x); f (f (f x)); ...]
val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a genDual 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 genCalls 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 : _ gen -> boolCheck whether the enum is empty. Pops an element, if any
val fold : ('b -> 'a -> 'b) -> 'b -> 'a gen -> 'bFold on the generator, tail-recursively. Consumes the generator.
val reduce : ('a -> 'a -> 'a) -> 'a gen -> 'aFold on non-empty sequences. Consumes the generator.
Like fold, but keeping successive values of the accumulator. Consumes the generator.
val iter : ('a -> unit) -> 'a gen -> unitIterate on the enum, consumes it.
val iteri : (int -> 'a -> unit) -> 'a gen -> unitIterate on elements with their index in the enum, from 0, consuming it.
val length : _ gen -> intLength of an enum (linear time), consuming it
Lazy map. No iteration is performed now, the function will be called when the result is traversed.
Append the two enums; the result contains the elements of the first, then the elements of the second enum.
val flatten : 'a Gen_intf.gen gen -> 'a genFlatten the enumeration of generators
val flat_map : ('a -> 'b Gen_intf.gen) -> 'a gen -> 'b genMonadic bind; each element is transformed to a sub-enum which is then iterated on, before the next element is processed, and so on.
val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a gen -> boolIs the given element, member of the enum?
val nth : int -> 'a gen -> 'an-th element, or Not_found
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
partition p l returns the elements that satisfy p, and the elements that do not satisfy p
val for_all : ('a -> bool) -> 'a gen -> boolIs the predicate true for all elements?
val exists : ('a -> bool) -> 'a gen -> boolIs the predicate true for at least one element?
val min : ?lt:('a -> 'a -> bool) -> 'a gen -> 'aMinimum element, according to the given comparison function.
Lexicographic comparison of generators. If a generator is a prefix of the other one, it is considered smaller.
val find : ('a -> bool) -> 'a gen -> 'a optionfind p e returns the first element of e to satisfy p, or None.
val sum : int gen -> intSum of all elements
Multiple iterators
Map on the two sequences. Stops once one of them is exhausted.
Iterate on the two sequences. Stops once one of them is exhausted.
Fold the common prefix of the two iterators
Succeeds if all pairs of elements satisfy the predicate. Ignores elements of an iterator if the other runs dry.
Succeeds if some pair of elements satisfy the predicate. Ignores elements of an iterator if the other runs dry.
Combine common part of the enums (stops when one is exhausted)
Complex combinators
val merge : 'a Gen_intf.gen gen -> 'a genPick elements fairly in each sub-generator. The merge of enums 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.
Intersection of two sorted sequences. Only elements that occur in both inputs appear in the output
Merge two sorted sequences into a sorted sequence
Sorted merge of multiple sorted sequences
val tee : ?n:int -> 'a gen -> 'a Gen_intf.gen listDuplicate the enum into n generators (default 2). The generators share the same underlying instance of the enum, so the optimal case is when they are consumed evenly
val round_robin : ?n:int -> 'a gen -> 'a Gen_intf.gen listSplit the enum into n generators in a fair way. Elements with index = k mod n with go to the k-th enum. n default value is 2.
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.
Put the separator element between all elements of the given enum
Cartesian product, in no predictable order. Works even if some of the arguments are infinite.
Group equal consecutive elements together.
Remove consecutive duplicate elements. Basically this is like fun e -> map List.hd (group e).
Sort according to the given comparison function. The enum must be finite.
Sort and remove duplicates. The enum must be finite.
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
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]]
All subsets of the enum (in no particular order). The ordering of the elements within each subset is unspecified.
Basic conversion functions
val of_list : 'a list -> 'a genEnumerate elements of the list
val to_list : 'a gen -> 'a listnon tail-call trasnformation to list, in the same order
val to_rev_list : 'a gen -> 'a listTail call conversion to list, in reverse order (more efficient)
val to_array : 'a gen -> 'a arrayConvert the enum to an array (not very efficient)
val of_array : ?start:int -> ?len:int -> 'a array -> 'a genIterate on (a slice of) the given array
val rand_int : int -> int genRandom ints in the given range.
val int_range : int -> int -> int genint_range a b enumerates integers between a and b, included. a is assumed to be smaller than b.
module Infix : sig ... endval (>>=) : 'a gen -> ('a -> 'b Gen_intf.gen) -> 'b genMonadic bind operator
val pp :
?start:string ->
?stop:string ->
?sep:string ->
?horizontal:bool ->
(Format.formatter -> 'a -> unit) ->
Format.formatter ->
'a gen ->
unitPretty print the content of the generator on a formatter.
Restartable generators
module Restart : sig ... endUtils
Store content of the transient generator in memory, to be able to iterate on it several times later. If possible, consider using combinators from Restart directly instead.
Same as persistent, but consumes the generator on demand (by chunks). This allows to make a restartable generator out of an ephemeral one, without paying a big cost upfront (nor even consuming it fully).