Module BatOption

module BatOption: sig .. end

Functions for the option type.

Options are an Ocaml standard type that can be either None (undefined) or Some x where x can be any value. Options are widely used in Ocaml to represent undefined values (a little like NULL in C, but in a type and memory safe way). This module adds some functions for working with options.
Author(s): Nicolas Cannasse, David Teller

type 'a t = 'a option

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

may f (Some x) calls f x and may f None does nothing.

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

map f (Some x) returns Some (f x) and map f None returns None.

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

bind f (Some x) returns f x and bind f None returns None.

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

default x (Some v) returns v and default x None returns x.

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

map_default f x (Some v) returns f v and map_default f x None returns x.

val is_none : 'a option -> bool

is_none None returns true otherwise it returns false.

val is_some : 'a option -> bool

is_some (Some x) returns true otherwise it returns false.

val get : 'a option -> 'a

get (Some x) returns x and get None raises No_value.

val get_exn : 'a option -> exn -> 'a

get_exn (Some x) e returns x and get_exn None e raises e.

val enum : 'a option -> 'a BatEnum.t

enum (Some x) returns the singleton x, while enum None returns the empty enumeration

val of_enum : 'a BatEnum.t -> 'a option

of_enum e consumes the first element of e, if it exists, and returns Some e. If e is empty, return None

exception No_value

Raised when calling get None.

The Option Monad

module Monad: sig .. end

This module provides everything needed to write and execute computations in the Option monad.

Boilerplate code

Printing

val print : ('a BatInnerIO.output -> 'b -> unit) ->
       'a BatInnerIO.output -> 'b t -> unit

val t_printer : 'a BatValue_printer.t -> 'a t BatValue_printer.t

val maybe_printer : 'a BatValue_printer.t -> 'a t BatValue_printer.t

module Labels: sig .. end

Operations on options, with labels.