module BatRef:sig
..end
Operations on references.
References are mutable values, i.e. "variables" which may actually change value during their life-time, as variables in imperative languages. References can be understood as 1-cell arrays and are typically used to implement imperative algorithms in OCaml.
References are useful but don't abuse them.
type'a
t ='a Stdlib.ref
The type of references.
val ref : 'a -> 'a Stdlib.ref
Return a fresh reference containing the given value.
val (!) : 'a Stdlib.ref -> 'a
!r
returns the current contents of reference r
.
Equivalent to fun r -> r.contents
.
val (:=) : 'a Stdlib.ref -> 'a -> unit
r := a
stores the value of a
in reference r
.
Equivalent to fun r v -> r.contents <- v
.
val set : 'a Stdlib.ref -> 'a -> unit
As :=
val get : 'a Stdlib.ref -> 'a
As !
val copy : 'a Stdlib.ref -> 'a Stdlib.ref
copy r
returns a new reference with the same initial
content as r
.
val pre : 'a Stdlib.ref -> ('a -> 'a) -> 'a
Perform an operation on a reference and return the new value of that reference.
For instance, if x
is a reference to 1
,
pre x ( ( + ) 1)
returns 2
and sets x
to 2
.
val post : 'a Stdlib.ref -> ('a -> 'a) -> 'a
Perform an operation on a reference and return the previous value of that reference.
For instance, if x
is a reference to 1
,
post x ( ( + ) 1)
returns 1
and sets x
to 2
.
val swap : 'a Stdlib.ref -> 'a Stdlib.ref -> unit
swap a b
puts !b
in a
and !a
in b
val post_incr : int Stdlib.ref -> int
Increment an integer, return the old value.
Comparable to C or Java's i++
.
val post_decr : int Stdlib.ref -> int
Decrement an integer, return the old value.
Comparable to C or Java 's i--
.
val pre_incr : int Stdlib.ref -> int
Increment an integer, return the new value.
Comparable to C or Java's ++i
.
val pre_decr : int Stdlib.ref -> int
Increment an integer, return the new value.
Comparable to C or Java's --i
.
val protect : 'a Stdlib.ref -> 'a -> (unit -> 'b) -> 'b
Assign a reference temporarily.
protect r v body
sets the value of r
to v
and executes
body
. Once body has been executed, whether termination happens
as a consequence of regular evaluation or exception, the previous
value of r
is restored.
val toggle : bool Stdlib.ref -> unit
Invert the boolean stored in the reference
val oset : 'a option Stdlib.ref -> 'a -> unit
Set the given option ref to Some x
val oget_exn : 'a option Stdlib.ref -> 'a
Get a value from an option ref;
Not_found
on oget_exn (ref None)
val print : ('b BatInnerIO.output -> 'a -> unit) ->
'b BatInnerIO.output -> 'a t -> unit
Given a printing function for the value in the ref, produce a printing function for the ref.
Example: IO.to_string (Ref.print Int.print) (ref 20) = "20"
val compare : 'a BatOrd.comp -> 'a Stdlib.ref BatOrd.comp
Given a comparison function, produce a comparison function for refs of that type.
Example: let a = ref 10 and b = ref 20 in Ref.compare Int.compare a b = -1
val ord : 'a BatOrd.ord -> 'a Stdlib.ref BatOrd.ord
Given an ordering function, produce an ordering function for refs of that type.
Example: let a = ref 10 and b = ref 20 in Ref.ord Int.ord a b = Ord.Lt
val eq : 'a BatOrd.eq -> 'a Stdlib.ref BatOrd.eq