package core_kernel

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package core_kernel
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type 'a t = 'a Lazy.t
include sig ... end
val bin_read_t : 'a Bin_prot.Read.reader -> 'a t Bin_prot.Read.reader
val __bin_read_t__ : 'a Bin_prot.Read.reader -> (Base.Int.t -> 'a t) Bin_prot.Read.reader
val bin_size_t : 'a Bin_prot.Size.sizer -> 'a t Bin_prot.Size.sizer
val bin_write_t : 'a Bin_prot.Write.writer -> 'a t Bin_prot.Write.writer
val bin_shape_t : Bin_prot.Shape.t -> Bin_prot.Shape.t
include module type of Base.Lazy with type 'a t := 'a t

A value of type 'a Lazy.t is a deferred computation, called a suspension, that has a result of type 'a. The special expression syntax lazy (expr) makes a suspension of the computation of expr, without computing expr itself yet. "Forcing" the suspension will then compute expr and return its result.

Note: lazy_t is the built-in type constructor used by the compiler for the lazy keyword. You should not use it directly. Always use Lazy.t instead.

Note: Lazy.force is not thread-safe. If you use this module in a multi-threaded program, you will need to add some locks.

Note: if the program is compiled with the -rectypes option, ill-founded recursive definitions of the form let rec x = lazy x or let rec x = lazy(lazy(...(lazy x))) are accepted by the type-checker and lead, when forced, to ill-formed values that trigger infinite loops in the garbage collector and other parts of the run-time system. Without the -rectypes option, such ill-founded recursive definitions are rejected by the type-checker.

include sig ... end
val t_of_sexp : (Base.Sexp.t -> 'a) -> Base.Sexp.t -> 'a t
val sexp_of_t : ('a -> Base.Sexp.t) -> 'a t -> Base.Sexp.t
val hash_fold_t : (Base.Hash.state -> 'a -> Base.Hash.state) -> Base.Hash.state -> 'a t -> Base.Hash.state
val compare : ('a -> 'a -> int) -> 'a t -> 'a t -> int
include Base.Monad.S with type 'a t := 'a t
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t

t >>= f returns a computation that sequences the computations represented by two monad elements. The resulting computation first does t to yield a value v, and then runs the computation returned by f v.

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

t >>| f is t >>= (fun a -> return (f a)).

module Monad_infix = Base.Lazy.Monad_infix
val bind : 'a t -> f:('a -> 'b t) -> 'b t

bind t ~f = t >>= f

val return : 'a -> 'a t

return v returns the (trivial) computation that returns v.

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

map t ~f is t >>| f.

val join : 'a t t -> 'a t

join t is t >>= (fun t' -> t').

val ignore_m : 'a t -> unit t

ignore_m t is map t ~f:(fun _ -> ()). ignore_m used to be called ignore, but we decided that was a bad name, because it shadowed the widely used Pervasives.ignore. Some monads still do let ignore = ignore_m for historical reasons.

val all : 'a t list -> 'a list t
val all_ignore : unit t list -> unit t
module Let_syntax = Base.Lazy.Let_syntax
exception Undefined
val force : 'a t -> 'a

force x forces the suspension x and returns its result. If x has already been forced, Lazy.force x returns the same value again without recomputing it. If it raised an exception, the same exception is raised again. Raise Undefined if the forcing of x tries to force x itself recursively.

val force_val : 'a t -> 'a

Like force except that force_val x does not use an exception handler, so it may be more efficient. However, if the computation of x raises an exception, it is unspecified whether force_val x raises the same exception or Undefined.

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

from_fun f is the same as lazy (f ()) but slightly more efficient if f is a variable. from_fun should only be used if the function f is already defined. In particular it is always less efficient to write from_fun (fun () -> expr) than lazy expr.

val from_val : 'a -> 'a t

from_val v returns an already-forced suspension of v (where v can be any expression). Essentially, from_val expr is the same as let var = expr in lazy var.

val is_val : 'a t -> bool

is_val x returns true if x has already been forced and did not raise an exception.

module T_unforcing = Base.Lazy.T_unforcing

This type offers a serialization function sexp_of_t that won't force its argument. Instead, it will serialize the 'a if it is available, or just use a custom string indicating is not forced. Note that this is not a round-trippable type, thus the type does not expose of_sexp. To be used in debug code for example, or while tracking an Heisenbug, etc.

module Stable : sig ... end
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