Module Frama_c_kernel.Option

Extend the option type to a full fleshed monad. Be wary that the parameters order of the bind function are reversed compared to the standard library.

include Monad.S_with_product with type 'a t = 'a option
val return : 'a -> 'a option
val flatten : 'a option option -> 'a option
module Bool : sig ... end
module Option : sig ... end
module List : sig ... end
module Operators : sig ... end
include module type of Option

Options

type 'a t = 'a option =
  1. | None
  2. | Some of 'a

The type for option values. Either None or a value Some v.

val none : 'a option

none is None.

val some : 'a -> 'a option

some v is Some v.

val value : 'a option -> default:'a -> 'a

value o ~default is v if o is Some v and default otherwise.

val get : 'a option -> 'a

get o is v if o is Some v and raise otherwise.

val join : 'a option option -> 'a option

join oo is Some v if oo is Some (Some v) and None otherwise.

val map : ('a -> 'b) -> 'a option -> 'b option

map f o is None if o is None and Some (f v) if o is Some v.

val product : 'a option -> 'b option -> ('a * 'b) option

product o0 o1 is Some (v0, v1) if o0 is Some v0 and o1 is Some v1 and None otherwise.

  • since 5.5
val fold : none:'a -> some:('b -> 'a) -> 'b option -> 'a

fold ~none ~some o is none if o is None and some v if o is Some v.

val iter : ('a -> unit) -> 'a option -> unit

iter f o is f v if o is Some v and () otherwise.

val blend : ('a -> 'a -> 'a) -> 'a option -> 'a option -> 'a option

blend f o1 o2 is o1 if o2 is None, o2 if o1 is None, and Some (f v1 v2) if o1 is Some v1 and o2 is Some v2.

  • since 5.5
val for_all : ('a -> bool) -> 'a option -> bool

for_all p behaves like List.for_all p on a list of zero or one element:

  • for_all p None is true,
  • for_all p (Some v) is p v.
  • since 5.5
val exists : ('a -> bool) -> 'a option -> bool

exists p behaves like List.exists p on a list of zero or one element:

  • exists p None is false,
  • exists p (Some v) is p v.
  • since 5.5

Predicates and comparisons

val is_none : 'a option -> bool

is_none o is true if and only if o is None.

val is_some : 'a option -> bool

is_some o is true if and only if o is Some o.

val equal : ('a -> 'a -> bool) -> 'a option -> 'a option -> bool

equal eq o0 o1 is true if and only if o0 and o1 are both None or if they are Some v0 and Some v1 and eq v0 v1 is true.

val compare : ('a -> 'a -> int) -> 'a option -> 'a option -> int

compare cmp o0 o1 is a total order on options using cmp to compare values wrapped by Some _. None is smaller than Some _ values.

Converting

val to_result : none:'e -> 'a option -> ('a, 'e) result

to_result ~none o is Ok v if o is Some v and Error none otherwise.

val to_list : 'a option -> 'a list

to_list o is [] if o is None and [v] if o is Some v.

val to_seq : 'a option -> 'a Seq.t

to_seq o is o as a sequence. None is the empty sequence and Some v is the singleton sequence containing v.

Syntax

module Syntax : sig ... end

Binding operators. See manual section 12.23 for details.

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

Reverse Stdlib.Option.bind parameters for monad compatibility. bind f o is f v if o is Some v and None if o is None.