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Option Module

Contains operations for working with options.

Functions and values

Function or value Description

Option.bind binder option

Full Usage: Option.bind binder option

Parameters:
    binder : 'T -> 'U option - A function that takes the value of type T from an option and transforms it into an option containing a value of type U.
    option : 'T option - The input option.

Returns: 'U option An option of the output type of the binder.
Modifiers: inline
Type parameters: 'T, 'U

bind f inp evaluates to match inp with None -> None | Some x -> f x

binder : 'T -> 'U option

A function that takes the value of type T from an option and transforms it into an option containing a value of type U.

option : 'T option

The input option.

Returns: 'U option

An option of the output type of the binder.

Example

 let tryParse (input: string) =
     match System.Int32.TryParse input with
     | true, v -> Some v
     | false, _ -> None
 None |> Option.bind tryParse // evaluates to None
 Some "42" |> Option.bind tryParse // evaluates to Some 42
 Some "Forty-two" |> Option.bind tryParse // evaluates to None
val tryParse: input: string -> int option
val input: string
Multiple items
val string: value: 'T -> string

--------------------
type string = System.String
namespace System
[<Struct>] type Int32 = member CompareTo: value: int -> int + 1 overload member Equals: obj: int -> bool + 1 overload member GetHashCode: unit -> int member GetTypeCode: unit -> TypeCode member ToString: unit -> string + 3 overloads member TryFormat: utf8Destination: Span<byte> * bytesWritten: byref<int> * ?format: ReadOnlySpan<char> * ?provider: IFormatProvider -> bool + 1 overload static member Abs: value: int -> int static member BigMul: left: int * right: int -> int64 static member Clamp: value: int * min: int * max: int -> int static member CopySign: value: int * sign: int -> int ...
<summary>Represents a 32-bit signed integer.</summary>
System.Int32.TryParse(s: string, result: byref<int>) : bool
System.Int32.TryParse(s: System.ReadOnlySpan<char>, result: byref<int>) : bool
System.Int32.TryParse(utf8Text: System.ReadOnlySpan<byte>, result: byref<int>) : bool
System.Int32.TryParse(s: string, provider: System.IFormatProvider, result: byref<int>) : bool
System.Int32.TryParse(s: System.ReadOnlySpan<char>, provider: System.IFormatProvider, result: byref<int>) : bool
System.Int32.TryParse(utf8Text: System.ReadOnlySpan<byte>, provider: System.IFormatProvider, result: byref<int>) : bool
System.Int32.TryParse(s: string, style: System.Globalization.NumberStyles, provider: System.IFormatProvider, result: byref<int>) : bool
System.Int32.TryParse(s: System.ReadOnlySpan<char>, style: System.Globalization.NumberStyles, provider: System.IFormatProvider, result: byref<int>) : bool
System.Int32.TryParse(utf8Text: System.ReadOnlySpan<byte>, style: System.Globalization.NumberStyles, provider: System.IFormatProvider, result: byref<int>) : bool
val v: int
union case Option.Some: Value: 'T -> Option<'T>
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val bind: binder: ('T -> 'U option) -> option: 'T option -> 'U option

Option.contains value option

Full Usage: Option.contains value option

Parameters:
    value : 'T - The value to test for equality.
    option : 'T option - The input option.

Returns: bool True if the option is Some and contains a value equal to value, otherwise false.
Modifiers: inline
Type parameters: 'T

Evaluates to true if option is Some and its value is equal to value.

value : 'T

The value to test for equality.

option : 'T option

The input option.

Returns: bool

True if the option is Some and contains a value equal to value, otherwise false.

Example

 (99, None) ||> Option.contains // evaluates to false
 (99, Some 99) ||> Option.contains // evaluates to true
 (99, Some 100) ||> Option.contains // evaluates to false
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val contains: value: 'T -> option: 'T option -> bool (requires equality)
union case Option.Some: Value: 'T -> Option<'T>

Option.count option

Full Usage: Option.count option

Parameters:
    option : 'T option - The input option.

Returns: int A zero if the option is None, a one otherwise.
Modifiers: inline
Type parameters: 'T

count inp evaluates to match inp with None -> 0 | Some _ -> 1.

option : 'T option

The input option.

Returns: int

A zero if the option is None, a one otherwise.

Example

 None |> Option.count // evaluates to 0
 Some 99 |> Option.count // evaluates to 1
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val count: option: 'T option -> int
union case Option.Some: Value: 'T -> Option<'T>

Option.defaultValue value option

Full Usage: Option.defaultValue value option

Parameters:
    value : 'T - The specified default value.
    option : 'T option - The input option.

Returns: 'T The option if the option is Some, else the default value.
Modifiers: inline
Type parameters: 'T

Gets the value of the option if the option is Some, otherwise returns the specified default value.

Identical to the built-in defaultArg operator, except with the arguments swapped.

value : 'T

The specified default value.

option : 'T option

The input option.

Returns: 'T

The option if the option is Some, else the default value.

Example

 (99, None) ||> Option.defaultValue // evaluates to 99
 (99, Some 42) ||> Option.defaultValue // evaluates to 42
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val defaultValue: value: 'T -> option: 'T option -> 'T
union case Option.Some: Value: 'T -> Option<'T>

Option.defaultWith defThunk option

Full Usage: Option.defaultWith defThunk option

Parameters:
    defThunk : unit -> 'T - A thunk that provides a default value when evaluated.
    option : 'T option - The input option.

Returns: 'T The option if the option is Some, else the result of evaluating defThunk.
Modifiers: inline
Type parameters: 'T

Gets the value of the option if the option is Some, otherwise evaluates defThunk and returns the result.

defThunk is not evaluated unless option is None.

defThunk : unit -> 'T

A thunk that provides a default value when evaluated.

option : 'T option

The input option.

Returns: 'T

The option if the option is Some, else the result of evaluating defThunk.

Example

 None |> Option.defaultWith (fun () -> 99) // evaluates to 99
 Some 42 |> Option.defaultWith (fun () -> 99) // evaluates to 42
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val defaultWith: defThunk: (unit -> 'T) -> option: 'T option -> 'T
union case Option.Some: Value: 'T -> Option<'T>

Option.exists predicate option

Full Usage: Option.exists predicate option

Parameters:
    predicate : 'T -> bool - A function that evaluates to a boolean when given a value from the option type.
    option : 'T option - The input option.

Returns: bool False if the option is None, otherwise it returns the result of applying the predicate to the option value.
Modifiers: inline
Type parameters: 'T

exists p inp evaluates to match inp with None -> false | Some x -> p x.

predicate : 'T -> bool

A function that evaluates to a boolean when given a value from the option type.

option : 'T option

The input option.

Returns: bool

False if the option is None, otherwise it returns the result of applying the predicate to the option value.

Example

 None |> Option.exists (fun x -> x >= 5) // evaluates to false
 Some 42 |> Option.exists (fun x -> x >= 5) // evaluates to true
 Some 4 |> Option.exists (fun x -> x >= 5) // evaluates to false
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val exists: predicate: ('T -> bool) -> option: 'T option -> bool
val x: int
union case Option.Some: Value: 'T -> Option<'T>

Option.filter predicate option

Full Usage: Option.filter predicate option

Parameters:
    predicate : 'T -> bool - A function that evaluates whether the value contained in the option should remain, or be filtered out.
    option : 'T option - The input option.

Returns: 'T option The input if the predicate evaluates to true; otherwise, None.
Modifiers: inline
Type parameters: 'T

filter f inp evaluates to match inp with None -> None | Some x -> if f x then Some x else None.

predicate : 'T -> bool

A function that evaluates whether the value contained in the option should remain, or be filtered out.

option : 'T option

The input option.

Returns: 'T option

The input if the predicate evaluates to true; otherwise, None.

Example

 None |> Option.filter (fun x -> x >= 5) // evaluates to None
 Some 42 |> Option.filter (fun x -> x >= 5) // evaluates to Some 42
 Some 4 |> Option.filter (fun x -> x >= 5) // evaluates to None
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val filter: predicate: ('T -> bool) -> option: 'T option -> 'T option
val x: int
union case Option.Some: Value: 'T -> Option<'T>

Option.flatten option

Full Usage: Option.flatten option

Parameters:
Returns: 'T option The input value if the value is Some; otherwise, None.
Modifiers: inline
Type parameters: 'T

flatten inp evaluates to match inp with None -> None | Some x -> x

flatten is equivalent to bind id.

option : 'T option option

The input option.

Returns: 'T option

The input value if the value is Some; otherwise, None.

Example

 (None: int option option) |> Option.flatten // evaluates to None
 (Some ((None: int option))) |> Option.flatten // evaluates to None
 (Some (Some 42)) |> Option.flatten // evaluates to Some 42
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>
module Option from Microsoft.FSharp.Core
val flatten: option: 'T option option -> 'T option
union case Option.Some: Value: 'T -> Option<'T>

Option.fold folder state option

Full Usage: Option.fold folder state option

Parameters:
    folder : 'State -> 'T -> 'State - A function to update the state data when given a value from an option.
    state : 'State - The initial state.
    option : 'T option - The input option.

Returns: 'State The original state if the option is None, otherwise it returns the updated state with the folder and the option value.
Modifiers: inline
Type parameters: 'T, 'State

fold f s inp evaluates to match inp with None -> s | Some x -> f s x.

folder : 'State -> 'T -> 'State

A function to update the state data when given a value from an option.

state : 'State

The initial state.

option : 'T option

The input option.

Returns: 'State

The original state if the option is None, otherwise it returns the updated state with the folder and the option value.

Example

 (0, None) ||> Option.fold (fun accum x -> accum + x * 2) // evaluates to 0
 (0, Some 1) ||> Option.fold (fun accum x -> accum + x * 2) // evaluates to 2
 (10, Some 1) ||> Option.fold (fun accum x -> accum + x * 2) // evaluates to 12
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val fold<'T,'State> : folder: ('State -> 'T -> 'State) -> state: 'State -> option: 'T option -> 'State
val accum: int
val x: int
union case Option.Some: Value: 'T -> Option<'T>

Option.foldBack folder option state

Full Usage: Option.foldBack folder option state

Parameters:
    folder : 'T -> 'State -> 'State - A function to update the state data when given a value from an option.
    option : 'T option - The input option.
    state : 'State - The initial state.

Returns: 'State The original state if the option is None, otherwise it returns the updated state with the folder and the option value.
Modifiers: inline
Type parameters: 'T, 'State

fold f inp s evaluates to match inp with None -> s | Some x -> f x s.

folder : 'T -> 'State -> 'State

A function to update the state data when given a value from an option.

option : 'T option

The input option.

state : 'State

The initial state.

Returns: 'State

The original state if the option is None, otherwise it returns the updated state with the folder and the option value.

Example

 (None, 0) ||> Option.foldBack (fun x accum -> accum + x * 2) // evaluates to 0
 (Some 1, 0) ||> Option.foldBack (fun x accum -> accum + x * 2) // evaluates to 2
 (Some 1, 10) ||> Option.foldBack (fun x accum -> accum + x * 2) // evaluates to 12
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val foldBack: folder: ('T -> 'State -> 'State) -> option: 'T option -> state: 'State -> 'State
val x: int
val accum: int
union case Option.Some: Value: 'T -> Option<'T>

Option.forall predicate option

Full Usage: Option.forall predicate option

Parameters:
    predicate : 'T -> bool - A function that evaluates to a boolean when given a value from the option type.
    option : 'T option - The input option.

Returns: bool True if the option is None, otherwise it returns the result of applying the predicate to the option value.
Modifiers: inline
Type parameters: 'T

forall p inp evaluates to match inp with None -> true | Some x -> p x.

predicate : 'T -> bool

A function that evaluates to a boolean when given a value from the option type.

option : 'T option

The input option.

Returns: bool

True if the option is None, otherwise it returns the result of applying the predicate to the option value.

Example

 None |> Option.forall (fun x -> x >= 5) // evaluates to true
 Some 42 |> Option.forall (fun x -> x >= 5) // evaluates to true
 Some 4 |> Option.forall (fun x -> x >= 5) // evaluates to false
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val forall: predicate: ('T -> bool) -> option: 'T option -> bool
val x: int
union case Option.Some: Value: 'T -> Option<'T>

Option.get option

Full Usage: Option.get option

Parameters:
    option : 'T option - The input option.

Returns: 'T The value within the option.

Gets the value associated with the option.

option : 'T option

The input option.

Returns: 'T

The value within the option.

Example

 Some 42 |> Option.get // evaluates to 42
 (None: int option) |> Option.get // throws exception!
union case Option.Some: Value: 'T -> Option<'T>
module Option from Microsoft.FSharp.Core
val get: option: 'T option -> 'T
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>

Option.isNone option

Full Usage: Option.isNone option

Parameters:
    option : 'T option - The input option.

Returns: bool True if the option is None.
Modifiers: inline
Type parameters: 'T

Returns true if the option is None.

option : 'T option

The input option.

Returns: bool

True if the option is None.

Example

 None |> Option.isNone // evaluates to true
 Some 42 |> Option.isNone // evaluates to false
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val isNone: option: 'T option -> bool
union case Option.Some: Value: 'T -> Option<'T>

Option.isSome option

Full Usage: Option.isSome option

Parameters:
    option : 'T option - The input option.

Returns: bool True if the option is not None.
Modifiers: inline
Type parameters: 'T

Returns true if the option is not None.

option : 'T option

The input option.

Returns: bool

True if the option is not None.

Example

 None |> Option.isSome // evaluates to false
 Some 42 |> Option.isSome // evaluates to true
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val isSome: option: 'T option -> bool
union case Option.Some: Value: 'T -> Option<'T>

Option.iter action option

Full Usage: Option.iter action option

Parameters:
    action : 'T -> unit - A function to apply to the option value.
    option : 'T option - The input option.

Modifiers: inline
Type parameters: 'T

iter f inp executes match inp with None -> () | Some x -> f x.

action : 'T -> unit

A function to apply to the option value.

option : 'T option

The input option.

Example

 None |> Option.iter (printfn "%s") // does nothing
 Some "Hello world" |> Option.iter (printfn "%s") // prints "Hello world"
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val iter: action: ('T -> unit) -> option: 'T option -> unit
val printfn: format: Printf.TextWriterFormat<'T> -> 'T
union case Option.Some: Value: 'T -> Option<'T>

Option.map mapping option

Full Usage: Option.map mapping option

Parameters:
    mapping : 'T -> 'U - A function to apply to the option value.
    option : 'T option - The input option.

Returns: 'U option An option of the input value after applying the mapping function, or None if the input is None.
Modifiers: inline
Type parameters: 'T, 'U

map f inp evaluates to match inp with None -> None | Some x -> Some (f x).

mapping : 'T -> 'U

A function to apply to the option value.

option : 'T option

The input option.

Returns: 'U option

An option of the input value after applying the mapping function, or None if the input is None.

Example

 None |> Option.map (fun x -> x * 2) // evaluates to None
 Some 42 |> Option.map (fun x -> x * 2) // evaluates to Some 84
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val map: mapping: ('T -> 'U) -> option: 'T option -> 'U option
val x: int
union case Option.Some: Value: 'T -> Option<'T>

Option.map2 mapping option1 option2

Full Usage: Option.map2 mapping option1 option2

Parameters:
    mapping : 'T1 -> 'T2 -> 'U - A function to apply to the option values.
    option1 : 'T1 option - The first option.
    option2 : 'T2 option - The second option.

Returns: 'U option An option of the input values after applying the mapping function, or None if either input is None.
Modifiers: inline
Type parameters: 'T1, 'T2, 'U

map f option1 option2 evaluates to match option1, option2 with Some x, Some y -> Some (f x y) | _ -> None.

mapping : 'T1 -> 'T2 -> 'U

A function to apply to the option values.

option1 : 'T1 option

The first option.

option2 : 'T2 option

The second option.

Returns: 'U option

An option of the input values after applying the mapping function, or None if either input is None.

Example

 (None, None) ||> Option.map2 (fun x y -> x + y) // evaluates to None
 (Some 5, None) ||> Option.map2 (fun x y -> x + y) // evaluates to None
 (None, Some 10) ||> Option.map2 (fun x y -> x + y) // evaluates to None
 (Some 5, Some 10) ||> Option.map2 (fun x y -> x + y) // evaluates to Some 15
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val map2: mapping: ('T1 -> 'T2 -> 'U) -> option1: 'T1 option -> option2: 'T2 option -> 'U option
val x: int
val y: int
union case Option.Some: Value: 'T -> Option<'T>

Option.map3 mapping option1 option2 option3

Full Usage: Option.map3 mapping option1 option2 option3

Parameters:
    mapping : 'T1 -> 'T2 -> 'T3 -> 'U - A function to apply to the option values.
    option1 : 'T1 option - The first option.
    option2 : 'T2 option - The second option.
    option3 : 'T3 option - The third option.

Returns: 'U option An option of the input values after applying the mapping function, or None if any input is None.
Modifiers: inline
Type parameters: 'T1, 'T2, 'T3, 'U

map f option1 option2 option3 evaluates to match option1, option2, option3 with Some x, Some y, Some z -> Some (f x y z) | _ -> None.

mapping : 'T1 -> 'T2 -> 'T3 -> 'U

A function to apply to the option values.

option1 : 'T1 option

The first option.

option2 : 'T2 option

The second option.

option3 : 'T3 option

The third option.

Returns: 'U option

An option of the input values after applying the mapping function, or None if any input is None.

Example

 (None, None, None) |||> Option.map3 (fun x y z -> x + y + z) // evaluates to None
 (Some 100, None, None) |||> Option.map3 (fun x y z -> x + y + z) // evaluates to None
 (None, Some 100, None) |||> Option.map3 (fun x y z -> x + y + z) // evaluates to None
 (None, None, Some 100) |||> Option.map3 (fun x y z -> x + y + z) // evaluates to None
 (Some 5, Some 100, Some 10) |||> Option.map3 (fun x y z -> x + y + z) // evaluates to Some 115
union case Option.None: Option<'T>
module Option from Microsoft.FSharp.Core
val map3: mapping: ('T1 -> 'T2 -> 'T3 -> 'U) -> option1: 'T1 option -> option2: 'T2 option -> option3: 'T3 option -> 'U option
val x: int
val y: int
val z: int
union case Option.Some: Value: 'T -> Option<'T>

Option.ofNullable value

Full Usage: Option.ofNullable value

Parameters:
    value : Nullable<'T> - The input nullable value.

Returns: 'T option The result option.
Modifiers: inline
Type parameters: 'T

Convert a Nullable value to an option.

value : Nullable<'T>

The input nullable value.

Returns: 'T option

The result option.

Example

 System.Nullable<int>() |> Option.ofNullable // evaluates to None
 System.Nullable(42) |> Option.ofNullable // evaluates to Some 42
namespace System
Multiple items
[<Struct>] type Nullable<'T (requires default constructor and value type and 'T :> ValueType)> = new: value: 'T -> unit member Equals: other: obj -> bool member GetHashCode: unit -> int member GetValueOrDefault: unit -> 'T + 1 overload member ToString: unit -> string static member op_Explicit: value: Nullable<'T> -> 'T static member op_Implicit: value: 'T -> Nullable<'T> member HasValue: bool member Value: 'T
<summary>Represents a value type that can be assigned <see langword="null" />.</summary>
<typeparam name="T">The underlying value type of the <see cref="T:System.Nullable`1" /> generic type.</typeparam>


--------------------
type Nullable = static member Compare<'T (requires default constructor and value type and 'T :> ValueType)> : n1: Nullable<'T> * n2: Nullable<'T> -> int static member Equals<'T (requires default constructor and value type and 'T :> ValueType)> : n1: Nullable<'T> * n2: Nullable<'T> -> bool static member GetUnderlyingType: nullableType: Type -> Type static member GetValueRefOrDefaultRef<'T (requires default constructor and value type and 'T :> ValueType)> : nullable: byref<Nullable<'T>> -> inref<'T>
<summary>Supports a value type that can be assigned <see langword="null" />. This class cannot be inherited.</summary>

--------------------
System.Nullable ()
System.Nullable(value: 'T) : System.Nullable<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
module Option from Microsoft.FSharp.Core
val ofNullable: value: System.Nullable<'T> -> 'T option (requires default constructor and value type and 'T :> System.ValueType)

Option.ofObj value

Full Usage: Option.ofObj value

Parameters:
    value : 'T - The input value.

Returns: 'T option The result option.
Modifiers: inline
Type parameters: 'T

Convert a potentially null value to an option.

value : 'T

The input value.

Returns: 'T option

The result option.

Example

 (null: string) |> Option.ofObj // evaluates to None
 "not a null string" |> Option.ofObj // evaluates to (Some "not a null string")
Multiple items
val string: value: 'T -> string

--------------------
type string = System.String
module Option from Microsoft.FSharp.Core
val ofObj: value: 'T -> 'T option (requires 'T: null)

Option.ofValueOption voption

Full Usage: Option.ofValueOption voption

Parameters:
    voption : 'T voption - The input value option.

Returns: 'T option The resulting option.
Modifiers: inline
Type parameters: 'T

Convert a value option to an option.

voption : 'T voption

The input value option.

Returns: 'T option

The resulting option.

Example

 ValueSome 42 |> Option.ofValueOption // evaluates to Some 42
 (ValueNone: int voption) |> Option.ofValueOption // evaluates to None
union case ValueOption.ValueSome: 'T -> ValueOption<'T>
module Option from Microsoft.FSharp.Core
union case ValueOption.ValueNone: ValueOption<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T voption = ValueOption<'T>

Option.orElse ifNone option

Full Usage: Option.orElse ifNone option

Parameters:
    ifNone : 'T option - The value to use if option is None.
    option : 'T option - The input option.

Returns: 'T option The option if the option is Some, else the alternate option.
Modifiers: inline
Type parameters: 'T

Returns option if it is Some, otherwise returns ifNone.

ifNone : 'T option

The value to use if option is None.

option : 'T option

The input option.

Returns: 'T option

The option if the option is Some, else the alternate option.

Example

 ((None: int Option), None) ||> Option.orElse // evaluates to None
 (Some 99, None) ||> Option.orElse // evaluates to Some 99
 (None, Some 42) ||> Option.orElse // evaluates to Some 42
 (Some 99, Some 42) ||> Option.orElse // evaluates to Some 42
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
module Option from Microsoft.FSharp.Core
val orElse: ifNone: 'T option -> option: 'T option -> 'T option
union case Option.Some: Value: 'T -> Option<'T>

Option.orElseWith ifNoneThunk option

Full Usage: Option.orElseWith ifNoneThunk option

Parameters:
    ifNoneThunk : unit -> 'T option - A thunk that provides an alternate option when evaluated.
    option : 'T option - The input option.

Returns: 'T option The option if the option is Some, else the result of evaluating ifNoneThunk.
Modifiers: inline
Type parameters: 'T

Returns option if it is Some, otherwise evaluates ifNoneThunk and returns the result.

ifNoneThunk is not evaluated unless option is None.

ifNoneThunk : unit -> 'T option

A thunk that provides an alternate option when evaluated.

option : 'T option

The input option.

Returns: 'T option

The option if the option is Some, else the result of evaluating ifNoneThunk.

Example

 (None: int Option) |> Option.orElseWith (fun () -> None) // evaluates to None
 None |> Option.orElseWith (fun () -> (Some 99)) // evaluates to Some 99
 Some 42 |> Option.orElseWith (fun () -> None) // evaluates to Some 42
 Some 42 |> Option.orElseWith (fun () -> (Some 99)) // evaluates to Some 42
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
module Option from Microsoft.FSharp.Core
val orElseWith: ifNoneThunk: (unit -> 'T option) -> option: 'T option -> 'T option
union case Option.Some: Value: 'T -> Option<'T>

Option.toArray option

Full Usage: Option.toArray option

Parameters:
    option : 'T option - The input option.

Returns: 'T array The result array.
Modifiers: inline
Type parameters: 'T

Convert the option to an array of length 0 or 1.

option : 'T option

The input option.

Returns: 'T array

The result array.

Example

 (None: int option) |> Option.toArray // evaluates to [||]
 Some 42 |> Option.toArray // evaluates to [|42|]
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>
module Option from Microsoft.FSharp.Core
val toArray: option: 'T option -> 'T array
union case Option.Some: Value: 'T -> Option<'T>

Option.toList option

Full Usage: Option.toList option

Parameters:
    option : 'T option - The input option.

Returns: 'T list The result list.
Modifiers: inline
Type parameters: 'T

Convert the option to a list of length 0 or 1.

option : 'T option

The input option.

Returns: 'T list

The result list.

Example

 (None: int option) |> Option.toList // evaluates to []
 Some 42 |> Option.toList // evaluates to [42]
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>
module Option from Microsoft.FSharp.Core
val toList: option: 'T option -> 'T list
union case Option.Some: Value: 'T -> Option<'T>

Option.toNullable option

Full Usage: Option.toNullable option

Parameters:
    option : 'T option - The input option.

Returns: Nullable<'T> The result value.
Modifiers: inline
Type parameters: 'T

Convert the option to a Nullable value.

option : 'T option

The input option.

Returns: Nullable<'T>

The result value.

Example

 (None: int option) |> Option.toNullable // evaluates to new System.Nullable<int>()
 Some 42 |> Option.toNullable // evaluates to new System.Nullable(42)
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>
module Option from Microsoft.FSharp.Core
val toNullable: option: 'T option -> System.Nullable<'T> (requires default constructor and value type and 'T :> System.ValueType)
union case Option.Some: Value: 'T -> Option<'T>

Option.toObj value

Full Usage: Option.toObj value

Parameters:
    value : 'T option - The input value.

Returns: 'T The result value, which is null if the input was None.
Modifiers: inline
Type parameters: 'T

Convert an option to a potentially null value.

value : 'T option

The input value.

Returns: 'T

The result value, which is null if the input was None.

Example

 (None: string option) |> Option.toObj // evaluates to null
 Some "not a null string" |> Option.toObj // evaluates to "not a null string"
union case Option.None: Option<'T>
Multiple items
val string: value: 'T -> string

--------------------
type string = System.String
type 'T option = Option<'T>
module Option from Microsoft.FSharp.Core
val toObj: value: 'T option -> 'T (requires 'T: null)
union case Option.Some: Value: 'T -> Option<'T>

Option.toValueOption option

Full Usage: Option.toValueOption option

Parameters:
    option : 'T option - The input option.

Returns: 'T voption The resulting value option.
Modifiers: inline
Type parameters: 'T

Convert an option to a value option.

option : 'T option

The input option.

Returns: 'T voption

The resulting value option.

Example

 Some 42 |> Option.toValueOption // evaluates to ValueSome 42
 (None: int option) |> Option.toValueOption // evaluates to ValueNone
union case Option.Some: Value: 'T -> Option<'T>
module Option from Microsoft.FSharp.Core
union case Option.None: Option<'T>
Multiple items
val int: value: 'T -> int (requires member op_Explicit)

--------------------
type int = int32

--------------------
type int<'Measure> = int
type 'T option = Option<'T>

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