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Option Module

Namespace: FSharp.Core
Assembly: FSharp.Core.dll

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: option : `'T option option` - The input option. 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>

Option Module

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