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. Most functions consume elements.
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.
A generator may be called several times, yielding the next value each time. It returns
None when no elements remain
type 'a gen = 'a t
module type S = Gen_intf.S
NOTE: version informations ("@since" annotations) in CCGen_intf will not be reliable, for they will represent versions of Gen rather than containers.
val get : 'a t -> 'a option
Get the next value
val get_exn : 'a t -> 'a
Get the next value, or fails
val junk : 'a t -> unit
Drop the next value, discarding it.
val repeatedly : ( unit -> 'a ) -> 'a t
Call the same function an infinite number of times (useful for instance if the function is a random generator).
Operations on transient generators
val empty : 'a gen
Empty generator, with no elements
val singleton : 'a -> 'a gen
val repeat : 'a -> 'a gen
Repeat same element endlessly
val iterate : 'a -> ( 'a -> 'a ) -> 'a gen
iterate x f is
[x; f x; f (f x); f (f (f x)); ...]
val unfold : ( 'b -> ('a * 'b) option ) -> 'b -> 'a gen
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 gen
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.
val is_empty : _ gen -> bool
Check whether the enum is empty. Pops an element, if any
val fold : ( 'b -> 'a -> 'b ) -> 'b -> 'a gen -> 'b
Fold on the generator, tail-recursively. Consumes the generator.
val reduce : ( 'a -> 'a -> 'a ) -> 'a gen -> 'a
Fold on non-empty sequences. Consumes the generator.
fold, but keeping successive values of the accumulator. Consumes the generator.
val iter : ( 'a -> unit ) -> 'a gen -> unit
Iterate on the enum, consumes it.
val iteri : ( int -> 'a -> unit ) -> 'a gen -> unit
Iterate on elements with their index in the enum, from 0, consuming it.
val length : _ gen -> int
Length 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.
Monadic 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 -> bool
Is the given element, member of the enum?
val nth : int -> 'a gen -> 'a
n-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
Filter out elements that do not satisfy the predicate.
Maps some elements to 'b, drop the other ones
partition p l returns the elements that satisfy
p, and the elements that do not satisfy
val for_all : ( 'a -> bool ) -> 'a gen -> bool
Is the predicate true for all elements?
val exists : ( 'a -> bool ) -> 'a gen -> bool
Is the predicate true for at least one element?
val min : ?lt:( 'a -> 'a -> bool ) -> 'a gen -> 'a
Minimum 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 option
find p e returns the first element of
e to satisfy
p, or None.
val sum : int gen -> int
Sum of all elements
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)
Pick elements fairly in each sub-generator. The merge of enums
e1, e2, ... picks elements in
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,
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
Duplicate 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
Split 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
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.
val of_list : 'a list -> 'a gen
Enumerate elements of the list
val to_list : 'a gen -> 'a list
non tail-call trasnformation to list, in the same order
val to_rev_list : 'a gen -> 'a list
Tail call conversion to list, in reverse order (more efficient)
val to_array : 'a gen -> 'a array
Convert the enum to an array (not very efficient)
val of_array : ?start:int -> ?len:int -> 'a array -> 'a gen
Iterate on (a slice of) the given array
val rand_int : int -> int gen
Random ints in the given range.
val int_range : int -> int -> int gen
int_range a b enumerates integers between
a is assumed to be smaller than
module Infix : sig ... end
module Restart : sig ... end
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.
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).