diff --git a/src/absil/illib.fs b/src/absil/illib.fs
index ab92a747b5e304f78aa9f252440e1621f63832e5..69b0030f910734534fbb4aaabc1d086eed6bf12e 100644
--- a/src/absil/illib.fs
+++ b/src/absil/illib.fs
@@ -432,8 +432,10 @@ module List =
     let existsSquared f xss = xss |> List.exists (fun xs -> xs |> List.exists (fun x -> f x))
     let mapiFoldSquared f z xss =  mapFoldSquared f z (xss |> mapiSquared (fun i j x -> (i,j,x)))
 
-[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-module ValueOption =
+/// Because FSharp.Compiler.Service is a library that will target FSharp.Core 4.5.2 for the forseeable future,
+/// we need to stick these functions in this module rather than using the module functions for ValueOption
+/// that come after FSharp.Core 4.5.2.
+module ValueOptionInternal =
     let inline ofOption x = match x with Some x -> ValueSome x | None -> ValueNone
     let inline bind f x = match x with ValueSome x -> f x | ValueNone -> ValueNone
     let inline isSome x = match x with ValueSome _ -> true | ValueNone -> false
diff --git a/src/buildfromsource/FSharp.Compiler.Private/FSComp.fs b/src/buildfromsource/FSharp.Compiler.Private/FSComp.fs
index 1be5487161c863203a71b4ef20ca5b69809dadd6..10faa567545a464ea62e08d935e51ff4cdeee163 100644
--- a/src/buildfromsource/FSharp.Compiler.Private/FSComp.fs
+++ b/src/buildfromsource/FSharp.Compiler.Private/FSComp.fs
@@ -3197,10 +3197,10 @@ type internal SR private() =
     /// (Originally from ..\FSComp.txt:1044)
     static member tastInvalidAddressOfMutableAcrossAssemblyBoundary() = (1188, GetStringFunc("tastInvalidAddressOfMutableAcrossAssemblyBoundary",",,,") )
     /// Remove spaces between the type name and type parameter, e.g. \"type C<'T>\", not type \"C   <'T>\". Type parameters must be placed directly adjacent to the type name.
-    /// (Originally from ..\FSComp.txt:1045)
+    /// (Originally from ..\FSComp.txt:1043)
     static member parsNonAdjacentTypars() = (1189, GetStringFunc("parsNonAdjacentTypars",",,,") )
     /// Remove spaces between the type name and type parameter, e.g. \"C<'T>\", not \"C <'T>\". Type parameters must be placed directly adjacent to the type name.
-    /// (Originally from ..\FSComp.txt:1046)
+    /// (Originally from ..\FSComp.txt:1044)
     static member parsNonAdjacentTyargs() = (1190, GetStringFunc("parsNonAdjacentTyargs",",,,") )
     /// The use of the type syntax 'int C' and 'C  <int>' is not permitted here. Consider adjusting this type to be written in the form 'C<int>'
     /// (Originally from ..\FSComp.txt:1047)
diff --git a/src/fsharp/FSharp.Core/option.fs b/src/fsharp/FSharp.Core/option.fs
index f963c01fc79650aa216a61f646da69cb72759402..552d1c9231f841cd6423bddaa596d04ae329fd4b 100644
--- a/src/fsharp/FSharp.Core/option.fs
+++ b/src/fsharp/FSharp.Core/option.fs
@@ -2,91 +2,177 @@
 
 namespace Microsoft.FSharp.Core
 
-    open Microsoft.FSharp.Core.Operators
+open Microsoft.FSharp.Core.Operators
 
-    [<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-    module Option = 
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+module Option = 
 
-        [<CompiledName("GetValue")>]
-        let get option = match option with None -> invalidArg "option" (SR.GetString(SR.optionValueWasNone)) | Some x -> x
+    [<CompiledName("GetValue")>]
+    let get option = match option with None -> invalidArg "option" (SR.GetString(SR.optionValueWasNone)) | Some x -> x
 
-        [<CompiledName("IsSome")>]
-        let inline isSome option = match option with None -> false | Some _ -> true
+    [<CompiledName("IsSome")>]
+    let inline isSome option = match option with None -> false | Some _ -> true
 
-        [<CompiledName("IsNone")>]
-        let inline isNone option = match option with None -> true | Some _ -> false
+    [<CompiledName("IsNone")>]
+    let inline isNone option = match option with None -> true | Some _ -> false
 
-        [<CompiledName("DefaultValue")>]
-        let defaultValue value option = match option with None -> value | Some v -> v
+    [<CompiledName("DefaultValue")>]
+    let defaultValue value option = match option with None -> value | Some v -> v
 
-        [<CompiledName("DefaultWith")>]
-        let defaultWith defThunk option = match option with None -> defThunk () | Some v -> v
+    [<CompiledName("DefaultWith")>]
+    let defaultWith defThunk option = match option with None -> defThunk () | Some v -> v
 
-        [<CompiledName("OrElse")>]
-        let orElse ifNone option = match option with None -> ifNone | Some _ -> option
+    [<CompiledName("OrElse")>]
+    let orElse ifNone option = match option with None -> ifNone | Some _ -> option
 
-        [<CompiledName("OrElseWith")>]
-        let orElseWith ifNoneThunk option = match option with None -> ifNoneThunk () | Some _ -> option
+    [<CompiledName("OrElseWith")>]
+    let orElseWith ifNoneThunk option = match option with None -> ifNoneThunk () | Some _ -> option
 
-        [<CompiledName("Count")>]
-        let count option = match option with None -> 0 | Some _ -> 1
+    [<CompiledName("Count")>]
+    let count option = match option with None -> 0 | Some _ -> 1
 
-        [<CompiledName("Fold")>]
-        let fold<'T,'State> folder (state:'State) (option: option<'T>) = match option with None -> state | Some x -> folder state x
+    [<CompiledName("Fold")>]
+    let fold<'T,'State> folder (state:'State) (option: option<'T>) = match option with None -> state | Some x -> folder state x
 
-        [<CompiledName("FoldBack")>]
-        let foldBack<'T,'State> folder (option: option<'T>) (state:'State) =  match option with None -> state | Some x -> folder x state
+    [<CompiledName("FoldBack")>]
+    let foldBack<'T,'State> folder (option: option<'T>) (state:'State) =  match option with None -> state | Some x -> folder x state
 
-        [<CompiledName("Exists")>]
-        let exists predicate option = match option with None -> false | Some x -> predicate x
+    [<CompiledName("Exists")>]
+    let exists predicate option = match option with None -> false | Some x -> predicate x
 
-        [<CompiledName("ForAll")>]
-        let forall predicate option = match option with None -> true | Some x -> predicate x
+    [<CompiledName("ForAll")>]
+    let forall predicate option = match option with None -> true | Some x -> predicate x
 
-        [<CompiledName("Contains")>]
-        let inline contains value option = match option with None -> false | Some v -> v = value
+    [<CompiledName("Contains")>]
+    let inline contains value option = match option with None -> false | Some v -> v = value
 
-        [<CompiledName("Iterate")>]
-        let iter action option = match option with None -> () | Some x -> action x
+    [<CompiledName("Iterate")>]
+    let iter action option = match option with None -> () | Some x -> action x
 
-        [<CompiledName("Map")>]
-        let map mapping option = match option with None -> None | Some x -> Some (mapping x)
+    [<CompiledName("Map")>]
+    let map mapping option = match option with None -> None | Some x -> Some (mapping x)
 
-        [<CompiledName("Map2")>]
-        let map2 mapping option1 option2 = 
-            match option1, option2 with
-            | Some x, Some y -> Some (mapping x y)
-            | _ -> None
+    [<CompiledName("Map2")>]
+    let map2 mapping option1 option2 = 
+        match option1, option2 with
+        | Some x, Some y -> Some (mapping x y)
+        | _ -> None
 
-        [<CompiledName("Map3")>]
-        let map3 mapping option1 option2 option3 = 
-            match option1, option2, option3 with
-            | Some x, Some y, Some z -> Some (mapping x y z)
-            | _ -> None
+    [<CompiledName("Map3")>]
+    let map3 mapping option1 option2 option3 = 
+        match option1, option2, option3 with
+        | Some x, Some y, Some z -> Some (mapping x y z)
+        | _ -> None
 
-        [<CompiledName("Bind")>]
-        let bind binder option = match option with None -> None | Some x -> binder x
+    [<CompiledName("Bind")>]
+    let bind binder option = match option with None -> None | Some x -> binder x
 
-        [<CompiledName("Flatten")>]
-        let flatten option = match option with None -> None | Some x -> x
+    [<CompiledName("Flatten")>]
+    let flatten option = match option with None -> None | Some x -> x
 
-        [<CompiledName("Filter")>]
-        let filter predicate option = match option with None -> None | Some x -> if predicate x then Some x else None
+    [<CompiledName("Filter")>]
+    let filter predicate option = match option with None -> None | Some x -> if predicate x then Some x else None
 
-        [<CompiledName("ToArray")>]
-        let toArray option = match option with  None -> [| |] | Some x -> [| x |]
+    [<CompiledName("ToArray")>]
+    let toArray option = match option with  None -> [| |] | Some x -> [| x |]
 
-        [<CompiledName("ToList")>]
-        let toList option = match option with  None -> [ ] | Some x -> [ x ]
+    [<CompiledName("ToList")>]
+    let toList option = match option with  None -> [ ] | Some x -> [ x ]
 
-        [<CompiledName("ToNullable")>]
-        let toNullable option = match option with None -> System.Nullable() | Some v -> System.Nullable(v)
+    [<CompiledName("ToNullable")>]
+    let toNullable option = match option with None -> System.Nullable() | Some v -> System.Nullable(v)
 
-        [<CompiledName("OfNullable")>]
-        let ofNullable (value:System.Nullable<'T>) = if value.HasValue then Some value.Value else None
+    [<CompiledName("OfNullable")>]
+    let ofNullable (value:System.Nullable<'T>) = if value.HasValue then Some value.Value else None
 
-        [<CompiledName("OfObj")>]
-        let ofObj value = match value with null -> None | _ -> Some value
+    [<CompiledName("OfObj")>]
+    let ofObj value = match value with null -> None | _ -> Some value
 
-        [<CompiledName("ToObj")>]
-        let toObj value = match value with None -> null | Some x -> x
+    [<CompiledName("ToObj")>]
+    let toObj value = match value with None -> null | Some x -> x
+
+module ValueOption =
+
+    [<CompiledName("GetValue")>]
+    let get voption = match voption with ValueNone -> invalidArg "option" (SR.GetString(SR.optionValueWasNone)) | ValueSome x -> x
+
+    [<CompiledName("IsSome")>]
+    let inline isSome voption = match voption with ValueNone -> false | ValueSome _ -> true
+
+    [<CompiledName("IsNone")>]
+    let inline isNone voption = match voption with ValueNone -> true | ValueSome _ -> false
+
+    [<CompiledName("DefaultValue")>]
+    let defaultValue value voption = match voption with ValueNone -> value | ValueSome v -> v
+
+    [<CompiledName("DefaultWith")>]
+    let defaultWith defThunk voption = match voption with ValueNone -> defThunk () | ValueSome v -> v
+
+    [<CompiledName("OrElse")>]
+    let orElse ifNone voption = match voption with ValueNone -> ifNone | ValueSome _ -> voption
+
+    [<CompiledName("OrElseWith")>]
+    let orElseWith ifNoneThunk voption = match voption with ValueNone -> ifNoneThunk () | ValueSome _ -> voption
+
+    [<CompiledName("Count")>]
+    let count voption = match voption with ValueNone -> 0 | ValueSome _ -> 1
+
+    [<CompiledName("Fold")>]
+    let fold<'T,'State> folder (state:'State) (voption: voption<'T>) = match voption with ValueNone -> state | ValueSome x -> folder state x
+
+    [<CompiledName("FoldBack")>]
+    let foldBack<'T,'State> folder (voption: voption<'T>) (state:'State) =  match voption with ValueNone -> state | ValueSome x -> folder x state
+
+    [<CompiledName("Exists")>]
+    let exists predicate voption = match voption with ValueNone -> false | ValueSome x -> predicate x
+
+    [<CompiledName("ForAll")>]
+    let forall predicate voption = match voption with ValueNone -> true | ValueSome x -> predicate x
+
+    [<CompiledName("Contains")>]
+    let inline contains value voption = match voption with ValueNone -> false | ValueSome v -> v = value
+
+    [<CompiledName("Iterate")>]
+    let iter action voption = match voption with ValueNone -> () | ValueSome x -> action x
+
+    [<CompiledName("Map")>]
+    let map mapping voption = match voption with ValueNone -> ValueNone | ValueSome x -> ValueSome (mapping x)
+
+    [<CompiledName("Map2")>]
+    let map2 mapping voption1 voption2 = 
+        match voption1, voption2 with
+        | ValueSome x, ValueSome y -> ValueSome (mapping x y)
+        | _ -> ValueNone
+
+    [<CompiledName("Map3")>]
+    let map3 mapping voption1 voption2 voption3 = 
+        match voption1, voption2, voption3 with
+        | ValueSome x, ValueSome y, ValueSome z -> ValueSome (mapping x y z)
+        | _ -> ValueNone
+
+    [<CompiledName("Bind")>]
+    let bind binder voption = match voption with ValueNone -> ValueNone | ValueSome x -> binder x
+
+    [<CompiledName("Flatten")>]
+    let flatten voption = match voption with ValueNone -> ValueNone | ValueSome x -> x
+
+    [<CompiledName("Filter")>]
+    let filter predicate voption = match voption with ValueNone -> ValueNone | ValueSome x -> if predicate x then ValueSome x else ValueNone
+
+    [<CompiledName("ToArray")>]
+    let toArray voption = match voption with  ValueNone -> [| |] | ValueSome x -> [| x |]
+
+    [<CompiledName("ToList")>]
+    let toList voption = match voption with  ValueNone -> [ ] | ValueSome x -> [ x ]
+
+    [<CompiledName("ToNullable")>]
+    let toNullable voption = match voption with ValueNone -> System.Nullable() | ValueSome v -> System.Nullable(v)
+
+    [<CompiledName("OfNullable")>]
+    let ofNullable (value:System.Nullable<'T>) = if value.HasValue then ValueSome value.Value else ValueNone
+
+    [<CompiledName("OfObj")>]
+    let ofObj value = match value with null -> ValueNone | _ -> ValueSome value
+
+    [<CompiledName("ToObj")>]
+    let toObj value = match value with ValueNone -> null | ValueSome x -> x
diff --git a/src/fsharp/FSharp.Core/option.fsi b/src/fsharp/FSharp.Core/option.fsi
index a8f7af2ffce6e6bcedf89c2fd6271edcf00ac50c..739484ae8cf27bbe747764b2b2e080596670c158 100644
--- a/src/fsharp/FSharp.Core/option.fsi
+++ b/src/fsharp/FSharp.Core/option.fsi
@@ -2,199 +2,387 @@
 
 namespace Microsoft.FSharp.Core
 
-    open System
-    open Microsoft.FSharp.Core
-    open Microsoft.FSharp.Collections
-    open Microsoft.FSharp.Core.Operators
-    open Microsoft.FSharp.Collections
-
-    [<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
-    /// <summary>Basic operations on options.</summary>
-    module Option =
-        /// <summary>Returns true if the option is not None.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>True if the option is not None.</returns>
-        [<CompiledName("IsSome")>]
-        val inline isSome: option:'T option -> bool
-
-        /// <summary>Returns true if the option is None.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>True if the option is None.</returns>
-        [<CompiledName("IsNone")>]
-        val inline isNone: option:'T option -> bool
-
-        /// <summary>Gets the value of the option if the option is <c>Some</c>, otherwise returns the specified default value.</summary>
-        /// <param name="value">The specified default value.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The option if the option is Some, else the default value.</returns>
-        /// <remarks>Identical to the built-in <see cref="defaultArg"/> operator, except with the arguments swapped.</remarks>
-        [<CompiledName("DefaultValue")>]
-        val defaultValue: value:'T -> option:'T option -> 'T
-
-        /// <summary>Gets the value of the option if the option is <c>Some</c>, otherwise evaluates <paramref name="defThunk"/> and returns the result.</summary>
-        /// <param name="defThunk">A thunk that provides a default value when evaluated.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The option if the option is Some, else the result of evaluating <paramref name="defThunk"/>.</returns>
-        /// <remarks><paramref name="defThunk"/> is not evaluated unless <paramref name="option"/> is <c>None</c>.</remarks>
-        [<CompiledName("DefaultWith")>]
-        val defaultWith: defThunk:(unit -> 'T) -> option:'T option -> 'T
-
-        /// <summary>Returns <paramref name="option"/> if it is <c>Some</c>, otherwise returns <paramref name="ifNone"/>.</summary>
-        /// <param name="ifNone">The value to use if <paramref name="option"/> is <c>None</c>.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The option if the option is Some, else the alternate option.</returns>
-        [<CompiledName("OrElse")>]
-        val orElse: ifNone:'T option -> option:'T option -> 'T option
-
-        /// <summary>Returns <paramref name="option"/> if it is <c>Some</c>, otherwise evaluates <paramref name="ifNoneThunk"/> and returns the result.</summary>
-        /// <param name="ifNoneThunk">A thunk that provides an alternate option when evaluated.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The option if the option is Some, else the result of evaluating <paramref name="ifNoneThunk"/>.</returns>
-        /// <remarks><paramref name="ifNoneThunk"/> is not evaluated unless <paramref name="option"/> is <c>None</c>.</remarks>
-        [<CompiledName("OrElseWith")>]
-        val orElseWith: ifNoneThunk:(unit -> 'T option) -> option:'T option -> 'T option
-
-        /// <summary>Gets the value associated with the option.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>The value within the option.</returns>
-        /// <exception href="System.ArgumentException">Thrown when the option is None.</exception>
-        [<CompiledName("GetValue")>]
-        val get: option:'T option -> 'T
-
-        /// <summary><c>count inp</c> evaluates to <c>match inp with None -> 0 | Some _ -> 1</c>.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>A zero if the option is None, a one otherwise.</returns>
-        [<CompiledName("Count")>]
-        val count: option:'T option -> int
-
-        /// <summary><c>fold f s inp</c> evaluates to <c>match inp with None -> s | Some x -> f s x</c>.</summary>
-        /// <param name="folder">A function to update the state data when given a value from an option.</param>
-        /// <param name="state">The initial state.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The original state if the option is None, otherwise it returns the updated state with the folder
-        /// and the option value.</returns>
-        [<CompiledName("Fold")>]
-        val fold<'T,'State> : folder:('State -> 'T -> 'State) -> state:'State -> option:'T option -> 'State
-
-        /// <summary><c>fold f inp s</c> evaluates to <c>match inp with None -> s | Some x -> f x s</c>.</summary>
-        /// <param name="folder">A function to update the state data when given a value from an option.</param>
-        /// <param name="option">The input option.</param>
-        /// <param name="state">The initial state.</param>
-        /// <returns>The original state if the option is None, otherwise it returns the updated state with the folder
-        /// and the option value.</returns>
-        [<CompiledName("FoldBack")>]
-        val foldBack<'T,'State> : folder:('T -> 'State -> 'State) -> option:'T option -> state:'State -> 'State
-
-        /// <summary><c>exists p inp</c> evaluates to <c>match inp with None -> false | Some x -> p x</c>.</summary>
-        /// <param name="predicate">A function that evaluates to a boolean when given a value from the option type.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>False if the option is None, otherwise it returns the result of applying the predicate
-        /// to the option value.</returns>
-        [<CompiledName("Exists")>]
-        val exists: predicate:('T -> bool) -> option:'T option -> bool
-
-        /// <summary><c>forall p inp</c> evaluates to <c>match inp with None -> true | Some x -> p x</c>.</summary>
-        /// <param name="predicate">A function that evaluates to a boolean when given a value from the option type.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>True if the option is None, otherwise it returns the result of applying the predicate
-        /// to the option value.</returns>
-        [<CompiledName("ForAll")>]
-        val forall: predicate:('T -> bool) -> option:'T option -> bool
-
-        /// <summary>Evaluates to true if <paramref name="option"/> is <c>Some</c> and its value is equal to <paramref name="value"/>.</summary>
-        /// <param name="value">The value to test for equality.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>True if the option is <c>Some</c> and contains a value equal to <paramref name="value"/>, otherwise false.</returns>
-        [<CompiledName("Contains")>]
-        val inline contains: value:'T -> option:'T option -> bool when 'T : equality
-
-        /// <summary><c>iter f inp</c> executes <c>match inp with None -> () | Some x -> f x</c>.</summary>
-        /// <param name="action">A function to apply to the option value.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>Unit if the option is None, otherwise it returns the result of applying the predicate
-        /// to the option value.</returns>
-        [<CompiledName("Iterate")>]
-        val iter: action:('T -> unit) -> option:'T option -> unit
-
-        /// <summary><c>map f inp</c> evaluates to <c>match inp with None -> None | Some x -> Some (f x)</c>.</summary>
-        /// <param name="mapping">A function to apply to the option value.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>An option of the input value after applying the mapping function, or None if the input is None.</returns>
-        [<CompiledName("Map")>]
-        val map: mapping:('T -> 'U) -> option:'T option -> 'U option
-
-        /// <summary><c>map f option1 option2</c> evaluates to <c>match option1, option2 with Some x, Some y -> Some (f x y) | _ -> None</c>.</summary>
-        /// <param name="mapping">A function to apply to the option values.</param>
-        /// <param name="option1">The first option.</param>
-        /// <param name="option2">The second option.</param>
-        /// <returns>An option of the input values after applying the mapping function, or None if either input is None.</returns>
-        [<CompiledName("Map2")>]
-        val map2: mapping:('T1 -> 'T2 -> 'U) -> 'T1 option -> 'T2 option -> 'U option
-
-        /// <summary><c>map f option1 option2 option3</c> evaluates to <c>match option1, option2, option3 with Some x, Some y, Some z -> Some (f x y z) | _ -> None</c>.</summary>
-        /// <param name="mapping">A function to apply to the option values.</param>
-        /// <param name="option1">The first option.</param>
-        /// <param name="option2">The second option.</param>
-        /// <param name="option3">The third option.</param>
-        /// <returns>An option of the input values after applying the mapping function, or None if any input is None.</returns>
-        [<CompiledName("Map3")>]
-        val map3: mapping:('T1 -> 'T2 -> 'T3 -> 'U) -> 'T1 option -> 'T2 option -> 'T3 option -> 'U option
-
-        /// <summary><c>bind f inp</c> evaluates to <c>match inp with None -> None | Some x -> f x</c></summary>
-        /// <param name="binder">A function that takes the value of type T from an option and transforms it into
-        /// an option containing a value of type U.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>An option of the output type of the binder.</returns>
-        [<CompiledName("Bind")>]
-        val bind: binder:('T -> 'U option) -> option:'T option -> 'U option
-
-        /// <summary><c>flatten inp</c> evaluates to <c>match inp with None -> None | Some x -> x</c></summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>An option of the output type of the binder.</returns>
-        /// <remarks><c>flatten</c> is equivalent to <c>bind id</c>.</remarks>
-        [<CompiledName("Flatten")>]
-        val flatten: option:'T option option -> 'T option
-
-        /// <summary><c>filter f inp</c> evaluates to <c>match inp with None -> None | Some x -> if f x then Some x else None</c>.</summary>
-        /// <param name="predicate">A function that evaluates whether the value contained in the option should remain, or be filtered out.</param>
-        /// <param name="option">The input option.</param>
-        /// <returns>The input if the predicate evaluates to true; otherwise, None.</returns>
-        [<CompiledName("Filter")>]
-        val filter: predicate:('T -> bool) -> option:'T option -> 'T option
-
-        /// <summary>Convert the option to an array of length 0 or 1.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>The result array.</returns>
-        [<CompiledName("ToArray")>]
-        val toArray: option:'T option -> 'T[]
-
-        /// <summary>Convert the option to a list of length 0 or 1.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>The result list.</returns>
-        [<CompiledName("ToList")>]
-        val toList: option:'T option -> 'T list
-
-
-        /// <summary>Convert the option to a Nullable value.</summary>
-        /// <param name="option">The input option.</param>
-        /// <returns>The result value.</returns>
-        [<CompiledName("ToNullable")>]
-        val toNullable: option:'T option -> Nullable<'T>
-
-        /// <summary>Convert a Nullable value to an option.</summary>
-        /// <param name="value">The input nullable value.</param>
-        /// <returns>The result option.</returns>
-        [<CompiledName("OfNullable")>]
-        val ofNullable: value:Nullable<'T> -> 'T option 
-
-        /// <summary>Convert a potentially null value to an option.</summary>
-        /// <param name="value">The input value.</param>
-        /// <returns>The result option.</returns>
-        [<CompiledName("OfObj")>]
-        val ofObj: value: 'T -> 'T option  when 'T : null
-
-        /// <summary>Convert an option to a potentially null value.</summary>
-        /// <param name="value">The input value.</param>
-        /// <returns>The result value, which is null if the input was None.</returns>
-        [<CompiledName("ToObj")>]
-        val toObj: value: 'T option -> 'T when 'T : null
+open System
+open Microsoft.FSharp.Core
+open Microsoft.FSharp.Collections
+
+
+[<CompilationRepresentation(CompilationRepresentationFlags.ModuleSuffix)>]
+/// <summary>Basic operations on options.</summary>
+module Option =
+    /// <summary>Returns true if the option is not None.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>True if the option is not None.</returns>
+    [<CompiledName("IsSome")>]
+    val inline isSome: option:'T option -> bool
+
+    /// <summary>Returns true if the option is None.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>True if the option is None.</returns>
+    [<CompiledName("IsNone")>]
+    val inline isNone: option:'T option -> bool
+
+    /// <summary>Gets the value of the option if the option is <c>Some</c>, otherwise returns the specified default value.</summary>
+    /// <param name="value">The specified default value.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The option if the option is Some, else the default value.</returns>
+    /// <remarks>Identical to the built-in <see cref="defaultArg"/> operator, except with the arguments swapped.</remarks>
+    [<CompiledName("DefaultValue")>]
+    val defaultValue: value:'T -> option:'T option -> 'T
+
+    /// <summary>Gets the value of the option if the option is <c>Some</c>, otherwise evaluates <paramref name="defThunk"/> and returns the result.</summary>
+    /// <param name="defThunk">A thunk that provides a default value when evaluated.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The option if the option is Some, else the result of evaluating <paramref name="defThunk"/>.</returns>
+    /// <remarks><paramref name="defThunk"/> is not evaluated unless <paramref name="option"/> is <c>None</c>.</remarks>
+    [<CompiledName("DefaultWith")>]
+    val defaultWith: defThunk:(unit -> 'T) -> option:'T option -> 'T
+
+    /// <summary>Returns <paramref name="option"/> if it is <c>Some</c>, otherwise returns <paramref name="ifNone"/>.</summary>
+    /// <param name="ifNone">The value to use if <paramref name="option"/> is <c>None</c>.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The option if the option is Some, else the alternate option.</returns>
+    [<CompiledName("OrElse")>]
+    val orElse: ifNone:'T option -> option:'T option -> 'T option
+
+    /// <summary>Returns <paramref name="option"/> if it is <c>Some</c>, otherwise evaluates <paramref name="ifNoneThunk"/> and returns the result.</summary>
+    /// <param name="ifNoneThunk">A thunk that provides an alternate option when evaluated.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The option if the option is Some, else the result of evaluating <paramref name="ifNoneThunk"/>.</returns>
+    /// <remarks><paramref name="ifNoneThunk"/> is not evaluated unless <paramref name="option"/> is <c>None</c>.</remarks>
+    [<CompiledName("OrElseWith")>]
+    val orElseWith: ifNoneThunk:(unit -> 'T option) -> option:'T option -> 'T option
+
+    /// <summary>Gets the value associated with the option.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>The value within the option.</returns>
+    /// <exception href="System.ArgumentException">Thrown when the option is None.</exception>
+    [<CompiledName("GetValue")>]
+    val get: option:'T option -> 'T
+
+    /// <summary><c>count inp</c> evaluates to <c>match inp with None -> 0 | Some _ -> 1</c>.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>A zero if the option is None, a one otherwise.</returns>
+    [<CompiledName("Count")>]
+    val count: option:'T option -> int
+
+    /// <summary><c>fold f s inp</c> evaluates to <c>match inp with None -> s | Some x -> f s x</c>.</summary>
+    /// <param name="folder">A function to update the state data when given a value from an option.</param>
+    /// <param name="state">The initial state.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The original state if the option is None, otherwise it returns the updated state with the folder
+    /// and the option value.</returns>
+    [<CompiledName("Fold")>]
+    val fold<'T,'State> : folder:('State -> 'T -> 'State) -> state:'State -> option:'T option -> 'State
+
+    /// <summary><c>fold f inp s</c> evaluates to <c>match inp with None -> s | Some x -> f x s</c>.</summary>
+    /// <param name="folder">A function to update the state data when given a value from an option.</param>
+    /// <param name="option">The input option.</param>
+    /// <param name="state">The initial state.</param>
+    /// <returns>The original state if the option is None, otherwise it returns the updated state with the folder
+    /// and the option value.</returns>
+    [<CompiledName("FoldBack")>]
+    val foldBack<'T,'State> : folder:('T -> 'State -> 'State) -> option:'T option -> state:'State -> 'State
+
+    /// <summary><c>exists p inp</c> evaluates to <c>match inp with None -> false | Some x -> p x</c>.</summary>
+    /// <param name="predicate">A function that evaluates to a boolean when given a value from the option type.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>False if the option is None, otherwise it returns the result of applying the predicate
+    /// to the option value.</returns>
+    [<CompiledName("Exists")>]
+    val exists: predicate:('T -> bool) -> option:'T option -> bool
+
+    /// <summary><c>forall p inp</c> evaluates to <c>match inp with None -> true | Some x -> p x</c>.</summary>
+    /// <param name="predicate">A function that evaluates to a boolean when given a value from the option type.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>True if the option is None, otherwise it returns the result of applying the predicate
+    /// to the option value.</returns>
+    [<CompiledName("ForAll")>]
+    val forall: predicate:('T -> bool) -> option:'T option -> bool
+
+    /// <summary>Evaluates to true if <paramref name="option"/> is <c>Some</c> and its value is equal to <paramref name="value"/>.</summary>
+    /// <param name="value">The value to test for equality.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>True if the option is <c>Some</c> and contains a value equal to <paramref name="value"/>, otherwise false.</returns>
+    [<CompiledName("Contains")>]
+    val inline contains: value:'T -> option:'T option -> bool when 'T : equality
+
+    /// <summary><c>iter f inp</c> executes <c>match inp with None -> () | Some x -> f x</c>.</summary>
+    /// <param name="action">A function to apply to the option value.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>Unit if the option is None, otherwise it returns the result of applying the predicate
+    /// to the option value.</returns>
+    [<CompiledName("Iterate")>]
+    val iter: action:('T -> unit) -> option:'T option -> unit
+
+    /// <summary><c>map f inp</c> evaluates to <c>match inp with None -> None | Some x -> Some (f x)</c>.</summary>
+    /// <param name="mapping">A function to apply to the option value.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>An option of the input value after applying the mapping function, or None if the input is None.</returns>
+    [<CompiledName("Map")>]
+    val map: mapping:('T -> 'U) -> option:'T option -> 'U option
+
+    /// <summary><c>map f option1 option2</c> evaluates to <c>match option1, option2 with Some x, Some y -> Some (f x y) | _ -> None</c>.</summary>
+    /// <param name="mapping">A function to apply to the option values.</param>
+    /// <param name="option1">The first option.</param>
+    /// <param name="option2">The second option.</param>
+    /// <returns>An option of the input values after applying the mapping function, or None if either input is None.</returns>
+    [<CompiledName("Map2")>]
+    val map2: mapping:('T1 -> 'T2 -> 'U) -> 'T1 option -> 'T2 option -> 'U option
+
+    /// <summary><c>map f option1 option2 option3</c> evaluates to <c>match option1, option2, option3 with Some x, Some y, Some z -> Some (f x y z) | _ -> None</c>.</summary>
+    /// <param name="mapping">A function to apply to the option values.</param>
+    /// <param name="option1">The first option.</param>
+    /// <param name="option2">The second option.</param>
+    /// <param name="option3">The third option.</param>
+    /// <returns>An option of the input values after applying the mapping function, or None if any input is None.</returns>
+    [<CompiledName("Map3")>]
+    val map3: mapping:('T1 -> 'T2 -> 'T3 -> 'U) -> 'T1 option -> 'T2 option -> 'T3 option -> 'U option
+
+    /// <summary><c>bind f inp</c> evaluates to <c>match inp with None -> None | Some x -> f x</c></summary>
+    /// <param name="binder">A function that takes the value of type T from an option and transforms it into
+    /// an option containing a value of type U.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>An option of the output type of the binder.</returns>
+    [<CompiledName("Bind")>]
+    val bind: binder:('T -> 'U option) -> option:'T option -> 'U option
+
+    /// <summary><c>flatten inp</c> evaluates to <c>match inp with None -> None | Some x -> x</c></summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>An option of the output type of the binder.</returns>
+    /// <remarks><c>flatten</c> is equivalent to <c>bind id</c>.</remarks>
+    [<CompiledName("Flatten")>]
+    val flatten: option:'T option option -> 'T option
+
+    /// <summary><c>filter f inp</c> evaluates to <c>match inp with None -> None | Some x -> if f x then Some x else None</c>.</summary>
+    /// <param name="predicate">A function that evaluates whether the value contained in the option should remain, or be filtered out.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The input if the predicate evaluates to true; otherwise, None.</returns>
+    [<CompiledName("Filter")>]
+    val filter: predicate:('T -> bool) -> option:'T option -> 'T option
+
+    /// <summary>Convert the option to an array of length 0 or 1.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>The result array.</returns>
+    [<CompiledName("ToArray")>]
+    val toArray: option:'T option -> 'T[]
+
+    /// <summary>Convert the option to a list of length 0 or 1.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>The result list.</returns>
+    [<CompiledName("ToList")>]
+    val toList: option:'T option -> 'T list
+
+
+    /// <summary>Convert the option to a Nullable value.</summary>
+    /// <param name="option">The input option.</param>
+    /// <returns>The result value.</returns>
+    [<CompiledName("ToNullable")>]
+    val toNullable: option:'T option -> Nullable<'T>
+
+    /// <summary>Convert a Nullable value to an option.</summary>
+    /// <param name="value">The input nullable value.</param>
+    /// <returns>The result option.</returns>
+    [<CompiledName("OfNullable")>]
+    val ofNullable: value:Nullable<'T> -> 'T option 
+
+    /// <summary>Convert a potentially null value to an option.</summary>
+    /// <param name="value">The input value.</param>
+    /// <returns>The result option.</returns>
+    [<CompiledName("OfObj")>]
+    val ofObj: value: 'T -> 'T option  when 'T : null
+
+    /// <summary>Convert an option to a potentially null value.</summary>
+    /// <param name="value">The input value.</param>
+    /// <returns>The result value, which is null if the input was None.</returns>
+    [<CompiledName("ToObj")>]
+    val toObj: value: 'T option -> 'T when 'T : null
+
+/// <summary>Basic operations on value options.</summary>
+module ValueOption =
+    /// <summary>Returns true if the value option is not ValueNone.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>True if the value option is not ValueNone.</returns>
+    [<CompiledName("IsSome")>]
+    val inline isSome: voption:'T voption -> bool
+
+    /// <summary>Returns true if the value option is ValueNone.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>True if the voption is ValueNone.</returns>
+    [<CompiledName("IsNone")>]
+    val inline isNone: voption:'T voption -> bool
+
+    /// <summary>Gets the value of the value option if the option is <c>ValueSome</c>, otherwise returns the specified default value.</summary>
+    /// <param name="value">The specified default value.</param>
+    /// <param name="voption">The input voption.</param>
+    /// <returns>The voption if the voption is ValueSome, else the default value.</returns>
+    /// <remarks>Identical to the built-in <see cref="defaultArg"/> operator, except with the arguments swapped.</remarks>
+    [<CompiledName("DefaultValue")>]
+    val defaultValue: value:'T -> voption:'T voption -> 'T
+
+    /// <summary>Gets the value of the voption if the voption is <c>ValueSome</c>, otherwise evaluates <paramref name="defThunk"/> and returns the result.</summary>
+    /// <param name="defThunk">A thunk that provides a default value when evaluated.</param>
+    /// <param name="voption">The input voption.</param>
+    /// <returns>The voption if the voption is ValueSome, else the result of evaluating <paramref name="defThunk"/>.</returns>
+    /// <remarks><paramref name="defThunk"/> is not evaluated unless <paramref name="voption"/> is <c>ValueNone</c>.</remarks>
+    [<CompiledName("DefaultWith")>]
+    val defaultWith: defThunk:(unit -> 'T) -> voption:'T voption -> 'T
+
+    /// <summary>Returns <paramref name="option"/> if it is <c>Some</c>, otherwise returns <paramref name="ifNone"/>.</summary>
+    /// <param name="ifNone">The value to use if <paramref name="option"/> is <c>None</c>.</param>
+    /// <param name="option">The input option.</param>
+    /// <returns>The option if the option is Some, else the alternate option.</returns>
+    [<CompiledName("OrElse")>]
+    val orElse: ifNone:'T voption -> voption:'T voption -> 'T voption
+
+    /// <summary>Returns <paramref name="voption"/> if it is <c>Some</c>, otherwise evaluates <paramref name="ifNoneThunk"/> and returns the result.</summary>
+    /// <param name="ifNoneThunk">A thunk that provides an alternate value option when evaluated.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The voption if the voption is ValueSome, else the result of evaluating <paramref name="ifNoneThunk"/>.</returns>
+    /// <remarks><paramref name="ifNoneThunk"/> is not evaluated unless <paramref name="voption"/> is <c>ValueNone</c>.</remarks>
+    [<CompiledName("OrElseWith")>]
+    val orElseWith: ifNoneThunk:(unit -> 'T voption) -> voption:'T voption -> 'T voption
+
+    /// <summary>Gets the value associated with the option.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The value within the option.</returns>
+    /// <exception href="System.ArgumentException">Thrown when the option is ValueNone.</exception>
+    [<CompiledName("GetValue")>]
+    val get: voption:'T voption -> 'T
+
+    /// <summary><c>count inp</c> evaluates to <c>match inp with ValueNone -> 0 | ValueSome _ -> 1</c>.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>A zero if the option is ValueNone, a one otherwise.</returns>
+    [<CompiledName("Count")>]
+    val count: voption:'T voption -> int
+
+    /// <summary><c>fold f s inp</c> evaluates to <c>match inp with ValueNone -> s | ValueSome x -> f s x</c>.</summary>
+    /// <param name="folder">A function to update the state data when given a value from a value option.</param>
+    /// <param name="state">The initial state.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The original state if the option is ValueNone, otherwise it returns the updated state with the folder
+    /// and the voption value.</returns>
+    [<CompiledName("Fold")>]
+    val fold<'T,'State> : folder:('State -> 'T -> 'State) -> state:'State -> voption:'T voption -> 'State
+
+    /// <summary><c>fold f inp s</c> evaluates to <c>match inp with ValueNone -> s | ValueSome x -> f x s</c>.</summary>
+    /// <param name="folder">A function to update the state data when given a value from a value option.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <param name="state">The initial state.</param>
+    /// <returns>The original state if the option is ValueNone, otherwise it returns the updated state with the folder
+    /// and the voption value.</returns>
+    [<CompiledName("FoldBack")>]
+    val foldBack<'T,'State> : folder:('T -> 'State -> 'State) -> voption:'T voption -> state:'State -> 'State
+
+    /// <summary><c>exists p inp</c> evaluates to <c>match inp with ValueNone -> false | ValueSome x -> p x</c>.</summary>
+    /// <param name="predicate">A function that evaluates to a boolean when given a value from the option type.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>False if the option is ValueNone, otherwise it returns the result of applying the predicate
+    /// to the option value.</returns>
+    [<CompiledName("Exists")>]
+    val exists: predicate:('T -> bool) -> voption:'T voption -> bool
+
+    /// <summary><c>forall p inp</c> evaluates to <c>match inp with ValueNone -> true | ValueSome x -> p x</c>.</summary>
+    /// <param name="predicate">A function that evaluates to a boolean when given a value from the value option type.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>True if the option is None, otherwise it returns the result of applying the predicate
+    /// to the option value.</returns>
+    [<CompiledName("ForAll")>]
+    val forall: predicate:('T -> bool) -> voption:'T voption -> bool
+
+    /// <summary>Evaluates to true if <paramref name="voption"/> is <c>ValueSome</c> and its value is equal to <paramref name="value"/>.</summary>
+    /// <param name="value">The value to test for equality.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>True if the option is <c>ValueSome</c> and contains a value equal to <paramref name="value"/>, otherwise false.</returns>
+    [<CompiledName("Contains")>]
+    val inline contains: value:'T -> voption:'T voption -> bool when 'T : equality
+
+    /// <summary><c>iter f inp</c> executes <c>match inp with ValueNone -> () | ValueSome x -> f x</c>.</summary>
+    /// <param name="action">A function to apply to the voption value.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>Unit if the option is ValueNone, otherwise it returns the result of applying the predicate
+    /// to the voption value.</returns>
+    [<CompiledName("Iterate")>]
+    val iter: action:('T -> unit) -> voption:'T voption -> unit
+
+    /// <summary><c>map f inp</c> evaluates to <c>match inp with ValueNone -> ValueNone | ValueSome x -> ValueSome (f x)</c>.</summary>
+    /// <param name="mapping">A function to apply to the voption value.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>A value option of the input value after applying the mapping function, or ValueNone if the input is ValueNone.</returns>
+    [<CompiledName("Map")>]
+    val map: mapping:('T -> 'U) -> voption:'T voption -> 'U voption
+
+    /// <summary><c>map f voption1 voption2</c> evaluates to <c>match voption1, voption2 with ValueSome x, ValueSome y -> ValueSome (f x y) | _ -> ValueNone</c>.</summary>
+    /// <param name="mapping">A function to apply to the voption values.</param>
+    /// <param name="voption1">The first value option.</param>
+    /// <param name="voption2">The second value option.</param>
+    /// <returns>A value option of the input values after applying the mapping function, or ValueNone if either input is ValueNone.</returns>
+    [<CompiledName("Map2")>]
+    val map2: mapping:('T1 -> 'T2 -> 'U) -> voption1: 'T1 voption -> voption2: 'T2 voption -> 'U voption
+
+    /// <summary><c>map f voption1 voption2 voption3</c> evaluates to <c>match voption1, voption2, voption3 with ValueSome x, ValueSome y, ValueSome z -> ValueSome (f x y z) | _ -> ValueNone</c>.</summary>
+    /// <param name="mapping">A function to apply to the value option values.</param>
+    /// <param name="voption1">The first value option.</param>
+    /// <param name="voption2">The second value option.</param>
+    /// <param name="voption3">The third value option.</param>
+    /// <returns>A value option of the input values after applying the mapping function, or ValueNone if any input is ValueNone.</returns>
+    [<CompiledName("Map3")>]
+    val map3: mapping:('T1 -> 'T2 -> 'T3 -> 'U) -> 'T1 voption -> 'T2 voption -> 'T3 voption -> 'U voption
+
+    /// <summary><c>bind f inp</c> evaluates to <c>match inp with ValueNone -> ValueNone | ValueSome x -> f x</c></summary>
+    /// <param name="binder">A function that takes the value of type T from a value option and transforms it into
+    /// a value option containing a value of type U.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>An option of the output type of the binder.</returns>
+    [<CompiledName("Bind")>]
+    val bind: binder:('T -> 'U voption) -> voption:'T voption -> 'U voption
+
+    /// <summary><c>flatten inp</c> evaluates to <c>match inp with ValueNone -> ValueNone | ValueSome x -> x</c></summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>A value option of the output type of the binder.</returns>
+    /// <remarks><c>flatten</c> is equivalent to <c>bind id</c>.</remarks>
+    [<CompiledName("Flatten")>]
+    val flatten: voption:'T voption voption -> 'T voption
+
+    /// <summary><c>filter f inp</c> evaluates to <c>match inp with ValueNone -> ValueNone | ValueSome x -> if f x then ValueSome x else ValueNone</c>.</summary>
+    /// <param name="predicate">A function that evaluates whether the value contained in the value option should remain, or be filtered out.</param>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The input if the predicate evaluates to true; otherwise, ValueNone.</returns>
+    [<CompiledName("Filter")>]
+    val filter: predicate:('T -> bool) -> voption:'T voption -> 'T voption
+
+    /// <summary>Convert the value option to an array of length 0 or 1.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The result array.</returns>
+    [<CompiledName("ToArray")>]
+    val toArray: voption:'T voption -> 'T[]
+
+    /// <summary>Convert the value option to a list of length 0 or 1.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The result list.</returns>
+    [<CompiledName("ToList")>]
+    val toList: voption:'T voption -> 'T list
+
+    /// <summary>Convert the value option to a Nullable value.</summary>
+    /// <param name="voption">The input value option.</param>
+    /// <returns>The result value.</returns>
+    [<CompiledName("ToNullable")>]
+    val toNullable: voption:'T voption -> Nullable<'T>
+
+    /// <summary>Convert a Nullable value to a value option.</summary>
+    /// <param name="value">The input nullable value.</param>
+    /// <returns>The result value option.</returns>
+    [<CompiledName("OfNullable")>]
+    val ofNullable: value:Nullable<'T> -> 'T voption 
+
+    /// <summary>Convert a potentially null value to a value option.</summary>
+    /// <param name="value">The input value.</param>
+    /// <returns>The result value option.</returns>
+    [<CompiledName("OfObj")>]
+    val ofObj: value: 'T -> 'T voption  when 'T : null
+
+    /// <summary>Convert an option to a potentially null value.</summary>
+    /// <param name="value">The input value.</param>
+    /// <returns>The result value, which is null if the input was ValueNone.</returns>
+    [<CompiledName("ToObj")>]
+    val toObj: value: 'T voption -> 'T when 'T : null
diff --git a/src/fsharp/FSharp.Core/prim-types.fs b/src/fsharp/FSharp.Core/prim-types.fs
index 753a75204dc451e90951a54f6c64c8f1d9fb669c..7929ef775817682dcc4c70db1f93232803d8b7d8 100644
--- a/src/fsharp/FSharp.Core/prim-types.fs
+++ b/src/fsharp/FSharp.Core/prim-types.fs
@@ -3054,12 +3054,29 @@ namespace Microsoft.FSharp.Core
     [<StructuralEquality; StructuralComparison>]
     [<Struct>]
     [<CompiledName("FSharpValueOption`1")>]
+    [<DebuggerDisplay("ValueSome({Value})")>]
     type ValueOption<'T> =
         | ValueNone : 'T voption
         | ValueSome : 'T -> 'T voption
 
         member x.Value = match x with ValueSome x -> x | ValueNone -> raise (new System.InvalidOperationException("ValueOption.Value"))
 
+        [<DebuggerBrowsable(DebuggerBrowsableState.Never)>]
+        static member None : 'T voption = ValueNone
+
+        static member Some (value) : 'T voption = ValueSome(value)
+
+        [<DebuggerBrowsable(DebuggerBrowsableState.Never)>]
+        member x.IsNone = match x with ValueNone -> true | _ -> false
+
+        [<DebuggerBrowsable(DebuggerBrowsableState.Never)>]
+        member x.IsSome = match x with ValueSome _ -> true | _ -> false
+
+        static member op_Implicit (value) : 'T option = Some(value)
+
+        override x.ToString() = 
+           // x is non-null, hence ValueSome
+           "ValueSome("^anyToStringShowingNull x.Value^")"
 
     and 'T voption = ValueOption<'T>
 
diff --git a/src/fsharp/FSharp.Core/prim-types.fsi b/src/fsharp/FSharp.Core/prim-types.fsi
index 61786826a20e117a983404fe288707dea8c56a7f..a62b9d18783f145076358a8bf85030cca75e6d3f 100644
--- a/src/fsharp/FSharp.Core/prim-types.fsi
+++ b/src/fsharp/FSharp.Core/prim-types.fsi
@@ -1866,6 +1866,20 @@ namespace Microsoft.FSharp.Core
         /// <summary>Get the value of a 'ValueSome' option. An InvalidOperationException is raised if the option is 'ValueNone'.</summary>
         member Value : 'T
 
+        /// <summary>Create a value option value that is a 'ValueNone' value.</summary>
+        static member None : 'T voption
+
+        /// <summary>Create a value option value that is a 'Some' value.</summary>
+        /// <param name="value">The input value</param>
+        /// <returns>A value option representing the value.</returns>
+        static member Some : value:'T -> 'T voption
+        
+        /// <summary>Return 'true' if the value option is a 'ValueSome' value.</summary>
+        member IsSome : bool
+
+        /// <summary>Return 'true' if the value option is a 'ValueNone' value.</summary>
+        member IsNone : bool
+
     /// <summary>The type of optional values, represented as structs.</summary>
     ///
     /// <remarks>Use the constructors <c>ValueSome</c> and <c>ValueNone</c> to create values of this type.
diff --git a/src/fsharp/NameResolution.fs b/src/fsharp/NameResolution.fs
index 0b95e6f72f358de96fa1068c329ae809e993414a..e07e3a682fdc5cf2931fc0f7ad9e03be0660d51c 100644
--- a/src/fsharp/NameResolution.fs
+++ b/src/fsharp/NameResolution.fs
@@ -1100,7 +1100,7 @@ let AddEntityForProvidedType (amap: Import.ImportMap, modref: ModuleOrNamespaceR
     let tycon = Construct.NewProvidedTycon(resolutionEnvironment, st, importProvidedType, isSuppressRelocate, m)
     modref.ModuleOrNamespaceType.AddProvidedTypeEntity(tycon)
     let tcref = modref.NestedTyconRef tycon
-    System.Diagnostics.Debug.Assert(ValueOption.isSome modref.TryDeref)
+    System.Diagnostics.Debug.Assert(ValueOptionInternal.isSome modref.TryDeref)
     tcref
 
 
diff --git a/src/fsharp/Optimizer.fs b/src/fsharp/Optimizer.fs
index 116911167ebb61e8e5902eca5e2f959ab00157d4..b97e6b7da7a2fa293fe7a2f5275b583561247591 100644
--- a/src/fsharp/Optimizer.fs
+++ b/src/fsharp/Optimizer.fs
@@ -3162,7 +3162,7 @@ and OptimizeBinding cenv isRec env (TBind(vref, expr, spBind)) =
                     | None -> false
                     | Some mbrTyconRef ->
                     // Check we can deref system_MarshalByRefObject_tcref. When compiling against the Silverlight mscorlib we can't
-                    if ValueOption.isSome mbrTyconRef.TryDeref then
+                    if ValueOptionInternal.isSome mbrTyconRef.TryDeref then
                         // Check if this is a subtype of MarshalByRefObject
                         assert (cenv.g.system_MarshalByRefObject_ty.IsSome)
                         ExistsSameHeadTypeInHierarchy cenv.g cenv.amap vref.Range (generalizedTyconRef tcref) cenv.g.system_MarshalByRefObject_ty.Value
diff --git a/src/fsharp/QuotationTranslator.fs b/src/fsharp/QuotationTranslator.fs
index 99fdf6c751a36d25ab77db2b4ac14d9f961dfc58..24e86da1bad28fee2b647ce699233c310b861e7c 100644
--- a/src/fsharp/QuotationTranslator.fs
+++ b/src/fsharp/QuotationTranslator.fs
@@ -66,7 +66,7 @@ type QuotationGenerationScope =
 
     static member ComputeQuotationFormat g = 
         let deserializeExValRef = ValRefForIntrinsic g.deserialize_quoted_FSharp_40_plus_info 
-        if ValueOption.isSome deserializeExValRef.TryDeref then 
+        if ValueOptionInternal.isSome deserializeExValRef.TryDeref then 
             QuotationSerializationFormat.FSharp_40_Plus
         else 
             QuotationSerializationFormat.FSharp_20_Plus
diff --git a/src/fsharp/symbols/Symbols.fs b/src/fsharp/symbols/Symbols.fs
index ab4cc75a9777b2d2e62354d65ff175cfaf976f75..fa3fcccfc824d904c9d96889fcb948ea0a1419ad 100644
--- a/src/fsharp/symbols/Symbols.fs
+++ b/src/fsharp/symbols/Symbols.fs
@@ -86,7 +86,7 @@ module Impl =
     let entityIsUnresolved(entity:EntityRef) = 
         match entity with
         | ERefNonLocal(NonLocalEntityRef(ccu, _)) -> 
-            ccu.IsUnresolvedReference && ValueOption.isNone entity.TryDeref
+            ccu.IsUnresolvedReference && ValueOptionInternal.isNone entity.TryDeref
         | _ -> false
 
     let checkEntityIsResolved(entity:EntityRef) = 
@@ -755,11 +755,12 @@ and FSharpUnionCase(cenv, v: UnionCaseRef) =
                                )
 
 
-    let isUnresolved() = 
-        entityIsUnresolved v.TyconRef || ValueOption.isNone v.TryUnionCase
+    let isUnresolved() =
+        entityIsUnresolved v.TyconRef || ValueOptionInternal.isNone v.TryUnionCase 
+        
     let checkIsResolved() = 
         checkEntityIsResolved v.TyconRef
-        if ValueOption.isNone v.TryUnionCase then 
+        if ValueOptionInternal.isNone v.TryUnionCase then 
             invalidOp (sprintf "The union case '%s' could not be found in the target type" v.CaseName)
 
     member __.IsUnresolved = 
@@ -872,10 +873,10 @@ and FSharpField(cenv: SymbolEnv, d: FSharpFieldData)  =
 
     let isUnresolved() = 
         d.TryDeclaringTyconRef |> Option.exists entityIsUnresolved ||
-        match d with 
+        match d with
         | AnonField _ -> false
-        | RecdOrClass v ->  ValueOption.isNone v.TryRecdField
-        | Union (v, _) -> ValueOption.isNone v.TryUnionCase
+        | RecdOrClass v -> ValueOptionInternal.isNone v.TryRecdField 
+        | Union (v, _) -> ValueOptionInternal.isNone v.TryUnionCase 
         | ILField _ -> false
 
     let checkIsResolved() = 
@@ -883,10 +884,10 @@ and FSharpField(cenv: SymbolEnv, d: FSharpFieldData)  =
         match d with 
         | AnonField _ -> ()
         | RecdOrClass v -> 
-            if ValueOption.isNone v.TryRecdField then 
+            if ValueOptionInternal.isNone v.TryRecdField then 
                 invalidOp (sprintf "The record field '%s' could not be found in the target type" v.FieldName)
         | Union (v, _) -> 
-            if ValueOption.isNone v.TryUnionCase then 
+            if ValueOptionInternal.isNone v.TryUnionCase then 
                 invalidOp (sprintf "The union case '%s' could not be found in the target type" v.CaseName)
         | ILField _ -> ()
 
@@ -1378,7 +1379,7 @@ and FSharpMemberOrFunctionOrValue(cenv, d:FSharpMemberOrValData, item) =
     let isUnresolved() = 
         match fsharpInfo() with 
         | None -> false
-        | Some v -> ValueOption.isNone v.TryDeref
+        | Some v -> ValueOptionInternal.isNone v.TryDeref
 
     let checkIsResolved() = 
         if isUnresolved() then 
diff --git a/src/fsharp/tast.fs b/src/fsharp/tast.fs
index fc8354e34322169f9afb802dc67b9b4ae7553836..63e7412d9023d6b1e89271374fbd6288ddd04677 100644
--- a/src/fsharp/tast.fs
+++ b/src/fsharp/tast.fs
@@ -1901,7 +1901,7 @@ and [<Sealed; StructuredFormatDisplay("{DebugText}")>]
           |> List.tryFind (fun v -> match key.TypeForLinkage with 
                                     | None -> true
                                     | Some keyTy -> ccu.MemberSignatureEquality(keyTy,v.Type))
-          |> ValueOption.ofOption
+          |> ValueOptionInternal.ofOption
 
     /// Get a table of values indexed by logical name
     member mtyp.AllValsByLogicalName = 
@@ -3263,7 +3263,7 @@ and
             ValueSome tcr.binding
 
     /// Is the destination assembly available?
-    member tcr.CanDeref = ValueOption.isSome tcr.TryDeref
+    member tcr.CanDeref = ValueOptionInternal.isSome tcr.TryDeref
 
     /// Gets the data indicating the compiled representation of a type or module in terms of Abstract IL data structures.
     member x.CompiledRepresentation = x.Deref.CompiledRepresentation
@@ -3814,7 +3814,7 @@ and
         | None -> error(InternalError(sprintf "union case %s not found in type %s" x.CaseName x.TyconRef.LogicalName, x.TyconRef.Range))
 
     /// Try to dereference the reference 
-    member x.TryUnionCase = x.TyconRef.TryDeref |> ValueOption.bind (fun tcref -> tcref.GetUnionCaseByName x.CaseName |> ValueOption.ofOption)
+    member x.TryUnionCase = x.TyconRef.TryDeref |> ValueOptionInternal.bind (fun tcref -> tcref.GetUnionCaseByName x.CaseName |> ValueOptionInternal.ofOption)
 
     /// Get the attributes associated with the union case
     member x.Attribs = x.UnionCase.Attribs
@@ -3873,7 +3873,7 @@ and
         | None -> error(InternalError(sprintf "field %s not found in type %s" id tcref.LogicalName, tcref.Range))
 
     /// Try to dereference the reference 
-    member x.TryRecdField =  x.TyconRef.TryDeref |> ValueOption.bind (fun tcref -> tcref.GetFieldByName x.FieldName |> ValueOption.ofOption)
+    member x.TryRecdField =  x.TyconRef.TryDeref |> ValueOptionInternal.bind (fun tcref -> tcref.GetFieldByName x.FieldName |> ValueOptionInternal.ofOption)
 
     /// Get the attributes associated with the compiled property of the record field 
     member x.PropertyAttribs = x.RecdField.PropertyAttribs
diff --git a/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Core/OptionModule.fs b/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Core/OptionModule.fs
index 5726775deff7fe2df5d4bba0f8ce9cb54f7cc133..3fb4395cd6935d5a4ab16f1b294d3eb4bd7b67cc 100644
--- a/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Core/OptionModule.fs
+++ b/tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Core/OptionModule.fs
@@ -224,28 +224,224 @@ type ValueOptionTests() =
 
     [<Test>]
     member this.ValueOptionBasics () =
-        Assert.AreEqual( (ValueNone: int voption), (ValueNone: int voption))
-        Assert.True( (ValueNone: int voption) <= (ValueNone: int voption))
-        Assert.True( (ValueNone: int voption) >= (ValueNone: int voption))
-        Assert.True( (ValueNone: int voption) < (ValueSome 1: int voption))
-        Assert.True( (ValueSome 0: int voption) < (ValueSome 1: int voption))
-        Assert.True( (ValueSome 1: int voption) > (ValueSome 0: int voption))
-        Assert.False( (ValueSome 1: int voption) < (ValueNone : int voption))
-        Assert.True( (ValueSome 1: int voption) <= (ValueSome 1: int voption))
-        Assert.AreEqual( compare (ValueSome 1) (ValueSome 1), 0)
-        Assert.True( compare (ValueSome 0) (ValueSome 1) < 0)
-        Assert.True( compare (ValueNone: int voption) (ValueSome 1) < 0)
-        Assert.True( compare (ValueSome 1) (ValueNone : int voption) > 0)
-        Assert.AreEqual( ValueSome 1, ValueSome 1)
-        Assert.AreNotEqual( ValueSome 2, ValueSome 1)
-        Assert.AreEqual( ValueSome 2, ValueSome 2)
-        Assert.AreEqual( ValueSome (ValueSome 2), ValueSome (ValueSome 2))
-        Assert.AreNotEqual( ValueSome (ValueSome 2), ValueSome (ValueSome 1))
-        Assert.AreNotEqual( ValueSome (ValueSome 0), ValueSome ValueNone)
-        Assert.AreEqual( ValueSome (ValueNone: int voption), ValueSome (ValueNone: int voption))
-        Assert.AreEqual( (ValueSome (ValueNone: int voption)).Value, (ValueNone: int voption))
-        Assert.AreEqual( (ValueSome 1).Value, 1)
-        Assert.AreEqual( (ValueSome (1,2)).Value, (1,2))
+        Assert.AreEqual((ValueNone: int voption), (ValueNone: int voption))
+        Assert.True((ValueNone: int voption) <= (ValueNone: int voption))
+        Assert.True((ValueNone: int voption) >= (ValueNone: int voption))
+        Assert.True((ValueNone: int voption) < (ValueSome 1: int voption))
+        Assert.True((ValueSome 0: int voption) < (ValueSome 1: int voption))
+        Assert.True((ValueSome 1: int voption) > (ValueSome 0: int voption))
+        Assert.False((ValueSome 1: int voption) < (ValueNone : int voption))
+        Assert.True((ValueSome 1: int voption) <= (ValueSome 1: int voption))
+        Assert.AreEqual(compare (ValueSome 1) (ValueSome 1), 0)
+        Assert.True(compare (ValueSome 0) (ValueSome 1) < 0)
+        Assert.True(compare (ValueNone: int voption) (ValueSome 1) < 0)
+        Assert.True(compare (ValueSome 1) (ValueNone : int voption) > 0)
+        Assert.AreEqual(ValueSome 1, ValueSome 1)
+        Assert.AreNotEqual(ValueSome 2, ValueSome 1)
+        Assert.AreEqual(ValueSome 2, ValueSome 2)
+        Assert.AreEqual(ValueSome (ValueSome 2), ValueSome (ValueSome 2))
+        Assert.AreNotEqual(ValueSome (ValueSome 2), ValueSome (ValueSome 1))
+        Assert.AreNotEqual(ValueSome (ValueSome 0), ValueSome ValueNone)
+        Assert.AreEqual(ValueSome (ValueNone: int voption), ValueSome (ValueNone: int voption))
+        Assert.AreEqual((ValueSome (ValueNone: int voption)).Value, (ValueNone: int voption))
+        Assert.AreEqual((ValueSome 1).Value, 1)
+        Assert.AreEqual((ValueSome (1,2)).Value, (1,2))
         Assert.AreEqual(defaultValueArg ValueNone 1, 1)
         Assert.AreEqual(defaultValueArg (ValueSome 3) 1, 3)
+    
+    [<Test>]
+    member this.Flatten () =
+        Assert.AreEqual(ValueOption.flatten ValueNone, ValueNone)
+        Assert.AreEqual(ValueOption.flatten (ValueSome ValueNone), ValueNone)
+        Assert.AreEqual(ValueOption.flatten (ValueSome <| ValueSome 1), ValueSome 1)
+        Assert.AreEqual(ValueOption.flatten (ValueSome <| ValueSome ""), ValueSome "") 
+
+    [<Test>]
+    member this.FilterValueSomeIntegerWhenPredicateReturnsTrue () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter (fun _ -> true)
+
+            actual = ValueSome x
+            |> Assert.True
+        [0;1;-1;42] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeStringWhenPredicateReturnsTrue () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter (fun _ -> true)
+
+            actual = ValueSome x
+            |> Assert.True
+        [""; " "; "Foo"; "Bar"] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeIntegerWhenPredicateReturnsFalse () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter (fun _ -> false)
+
+            actual = ValueNone
+            |> Assert.True
+        [0; 1; -1; 1337] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeStringWhenPredicateReturnsFalse () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter (fun _ -> false)
+
+            actual= ValueNone
+            |> Assert.True
+        [""; "  "; "Ploeh"; "Fnaah"] |> List.iter test
 
+    [<Test>]
+    member this.FilterValueNoneReturnsCorrectResult () =
+        let test x =
+            let actual = ValueNone |> ValueOption.filter (fun _ -> x)
+
+            actual = ValueNone
+            |> Assert.True
+        [false; true] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeIntegerWhenPredicateEqualsInput () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter ((=) x)
+
+            actual = ValueSome x
+            |> Assert.True
+        [0; 1; -1; -2001] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeStringWhenPredicateEqualsInput () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter ((=) x)
+
+            actual = ValueSome x
+            |> Assert.True
+        [""; "     "; "Xyzz"; "Sgryt"] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeIntegerWhenPredicateDoesNotEqualsInput () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter ((<>) x)
+
+            actual = ValueNone
+            |> Assert.True
+        [0; 1; -1; 927] |> List.iter test
+
+    [<Test>]
+    member this.FilterValueSomeStringWhenPredicateDoesNotEqualsInput () =
+        let test x =
+            let actual = x |> ValueSome |> ValueOption.filter ((<>) x)
+
+            actual = ValueNone
+            |> Assert.True
+        [""; "     "; "Baz Quux"; "Corge grault"] |> List.iter test
+
+    [<Test>]
+    member this.Contains() =
+        Assert.IsFalse(ValueOption.contains 1 ValueNone)
+        Assert.IsTrue(ValueOption.contains 1 (ValueSome 1))
+
+        Assert.IsFalse(ValueOption.contains "" ValueNone)
+        Assert.IsTrue(ValueOption.contains "" (ValueSome ""))
+
+        Assert.IsFalse(ValueOption.contains ValueNone ValueNone)
+        Assert.IsTrue(ValueOption.contains ValueNone (ValueSome ValueNone))
+    [<Test>]
+    member this.OfToNullable() =
+        Assert.IsTrue(ValueOption.ofNullable (System.Nullable<int>()) = ValueNone)
+        Assert.IsTrue(ValueOption.ofNullable (System.Nullable<int>(3)) = ValueSome 3)
+
+        Assert.IsTrue(ValueOption.toNullable (ValueNone : int voption) = System.Nullable<int>())
+        Assert.IsTrue(ValueOption.toNullable (ValueNone : System.DateTime voption) = System.Nullable())
+        Assert.IsTrue(ValueOption.toNullable (ValueSome 3) = System.Nullable(3))
+
+    [<Test>]
+    member this.OfToObj() =
+        Assert.IsTrue(ValueOption.toObj (ValueSome "3") = "3")
+        Assert.IsTrue(ValueOption.toObj (ValueSome "") = "")
+        Assert.IsTrue(ValueOption.toObj (ValueSome null) = null)
+        Assert.IsTrue(ValueOption.toObj ValueNone = null)     
+     
+        Assert.IsTrue(ValueOption.ofObj "3" = ValueSome "3")
+        Assert.IsTrue(ValueOption.ofObj "" = ValueSome "")
+        Assert.IsTrue(ValueOption.ofObj [| "" |] = ValueSome [| "" |])
+        Assert.IsTrue(ValueOption.ofObj (null : string array) = ValueNone)
+        Assert.IsTrue(ValueOption.ofObj<string> null = ValueNone)
+        Assert.IsTrue(ValueOption.ofObj<string[]> null = ValueNone)
+        Assert.IsTrue(ValueOption.ofObj<int[]> null = ValueNone)
+
+    [<Test>]
+    member this.DefaultValue() =
+        Assert.AreEqual(ValueOption.defaultValue 3 ValueNone, 3)
+        Assert.AreEqual(ValueOption.defaultValue 3 (ValueSome 42), 42)
+        Assert.AreEqual(ValueOption.defaultValue "" ValueNone, "")
+        Assert.AreEqual(ValueOption.defaultValue "" (ValueSome "x"), "x")
+
+    [<Test>]
+    member this.DefaultWith() =
+        Assert.AreEqual(ValueOption.defaultWith (fun () -> 3) ValueNone, 3)
+        Assert.AreEqual(ValueOption.defaultWith (fun () -> "") ValueNone, "")
+
+        Assert.AreEqual(ValueOption.defaultWith assertWasNotCalledThunk (ValueSome 42), 42)
+        Assert.AreEqual(ValueOption.defaultWith assertWasNotCalledThunk (ValueSome ""), "")
+
+    [<Test>]
+    member this.OrElse() =
+        Assert.AreEqual(ValueOption.orElse ValueNone ValueNone, ValueNone)
+        Assert.AreEqual(ValueOption.orElse (ValueSome 3) ValueNone, ValueSome 3)
+        Assert.AreEqual(ValueOption.orElse ValueNone (ValueSome 42), ValueSome 42)
+        Assert.AreEqual(ValueOption.orElse (ValueSome 3) (ValueSome 42), ValueSome 42)
+
+        Assert.AreEqual(ValueOption.orElse (ValueSome "") ValueNone, ValueSome "")
+        Assert.AreEqual(ValueOption.orElse ValueNone (ValueSome "x"), ValueSome "x")
+        Assert.AreEqual(ValueOption.orElse (ValueSome "") (ValueSome "x"), ValueSome "x")
+
+    [<Test>]
+    member this.OrElseWith() =
+        Assert.AreEqual(ValueOption.orElseWith (fun () -> ValueNone) ValueNone, ValueNone)
+        Assert.AreEqual(ValueOption.orElseWith (fun () -> ValueSome 3) ValueNone, ValueSome 3)
+        Assert.AreEqual(ValueOption.orElseWith (fun () -> ValueSome "") ValueNone, ValueSome "")
+
+        Assert.AreEqual(ValueOption.orElseWith assertWasNotCalledThunk (ValueSome 42), ValueSome 42)
+        Assert.AreEqual(ValueOption.orElseWith assertWasNotCalledThunk (ValueSome ""), ValueSome "")
+
+    [<Test>]
+    member this.Map2() =
+        Assert.True(ValueOption.map2 (-) ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map2 (-) (ValueSome 1) ValueNone = ValueNone)
+        Assert.True(ValueOption.map2 (-) ValueNone (ValueSome 2) = ValueNone)
+        Assert.True(ValueOption.map2 (-) (ValueSome 1) (ValueSome 2) = ValueSome -1)
+
+        Assert.True(ValueOption.map2 (+) ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map2 (+) (ValueSome "x") ValueNone = ValueNone)
+        Assert.True(ValueOption.map2 (+) (ValueSome "x") (ValueSome "y") = ValueSome "xy")
+        Assert.True(ValueOption.map2 (+) ValueNone (ValueSome "y") = ValueNone)
+
+    [<Test>]
+    member this.Map3() =
+        let add3 x y z = string x + string y + string z
+        Assert.True(ValueOption.map3 add3 ValueNone ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 add3 (ValueSome 1) ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 add3 ValueNone (ValueSome 2) ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 add3 (ValueSome 1) (ValueSome 2) ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 add3 ValueNone ValueNone (ValueSome 3) = ValueNone)
+        Assert.True(ValueOption.map3 add3 (ValueSome 1) ValueNone (ValueSome 3) = ValueNone)
+        Assert.True(ValueOption.map3 add3 ValueNone (ValueSome 2) (ValueSome 3) = ValueNone)
+        Assert.True(ValueOption.map3 add3 (ValueSome 1) (ValueSome 2) (ValueSome 3) = ValueSome "123")
+
+        let concat3 x y z = x + y + z
+        Assert.True(ValueOption.map3 concat3 ValueNone ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 concat3 (ValueSome "x") ValueNone ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 concat3 ValueNone (ValueSome "y") ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 concat3 (ValueSome "x") (ValueSome "y") ValueNone = ValueNone)
+        Assert.True(ValueOption.map3 concat3 ValueNone ValueNone (ValueSome "z") = ValueNone)
+        Assert.True(ValueOption.map3 concat3 (ValueSome "x") ValueNone (ValueSome "z") = ValueNone)
+        Assert.True(ValueOption.map3 concat3 ValueNone (ValueSome "y") (ValueSome "z") = ValueNone)
+        Assert.True(ValueOption.map3 concat3 (ValueSome "x") (ValueSome "y") (ValueSome "z") = ValueSome "xyz")
+
+    [<Test>]
+    member this.MapBindEquivalenceProperties () =
+        let fn x = x + 3
+        Assert.AreEqual(ValueOption.map fn ValueNone, ValueOption.bind (fn >> ValueSome) ValueNone)
+        Assert.AreEqual(ValueOption.map fn (ValueSome 5), ValueOption.bind (fn >> ValueSome) (ValueSome 5))
\ No newline at end of file
diff --git a/tests/FSharp.Core.UnitTests/SurfaceArea.coreclr.fs b/tests/FSharp.Core.UnitTests/SurfaceArea.coreclr.fs
index fc3dbbbed5967a46af8beaa0bf0876691df64846..e3873c76b9c356062a699ab98b903c8887d4fe40 100644
--- a/tests/FSharp.Core.UnitTests/SurfaceArea.coreclr.fs
+++ b/tests/FSharp.Core.UnitTests/SurfaceArea.coreclr.fs
@@ -2192,6 +2192,13 @@ Microsoft.FSharp.Core.FSharpValueOption`1[T]: T Item
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T Value
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T get_Item()
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T get_Value()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean IsNone
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean IsSome
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean get_IsNone()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean get_IsSome()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] None
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] Some(T)
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] get_None()
 Microsoft.FSharp.Core.FSharpTypeFunc: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.FSharpTypeFunc: Int32 GetHashCode()
 Microsoft.FSharp.Core.FSharpTypeFunc: System.Object Specialize[T]()
@@ -2762,6 +2769,36 @@ Microsoft.FSharp.Core.OptionModule: TState FoldBack[T,TState](Microsoft.FSharp.C
 Microsoft.FSharp.Core.OptionModule: TState Fold[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[TState,Microsoft.FSharp.Core.FSharpFunc`2[T,TState]], TState, Microsoft.FSharp.Core.FSharpOption`1[T])
 Microsoft.FSharp.Core.OptionModule: T[] ToArray[T](Microsoft.FSharp.Core.FSharpOption`1[T])
 Microsoft.FSharp.Core.OptionModule: Void Iterate[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.Unit], Microsoft.FSharp.Core.FSharpOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean Contains[T](T, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean Equals(System.Object)
+Microsoft.FSharp.Core.ValueOption: Boolean Exists[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean ForAll[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean IsNone[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean IsSome[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Int32 Count[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Int32 GetHashCode()
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Collections.FSharpList`1[T] ToList[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Bind[T,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpValueOption`1[TResult]], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map2[T1,T2,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T1,Microsoft.FSharp.Core.FSharpFunc`2[T2,TResult]], Microsoft.FSharp.Core.FSharpValueOption`1[T1], Microsoft.FSharp.Core.FSharpValueOption`1[T2])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map3[T1,T2,T3,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T1,Microsoft.FSharp.Core.FSharpFunc`2[T2,Microsoft.FSharp.Core.FSharpFunc`2[T3,TResult]]], Microsoft.FSharp.Core.FSharpValueOption`1[T1], Microsoft.FSharp.Core.FSharpValueOption`1[T2], Microsoft.FSharp.Core.FSharpValueOption`1[T3])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map[T,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T,TResult], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] Filter[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] Flatten[T](Microsoft.FSharp.Core.FSharpValueOption`1[Microsoft.FSharp.Core.FSharpValueOption`1[T]])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OfNullable[T](System.Nullable`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OfObj[T](T)
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OrElseWith[T](Microsoft.FSharp.Core.FSharpFunc`2[Microsoft.FSharp.Core.Unit,Microsoft.FSharp.Core.FSharpValueOption`1[T]], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OrElse[T](Microsoft.FSharp.Core.FSharpValueOption`1[T], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: System.Nullable`1[T] ToNullable[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: System.String ToString()
+Microsoft.FSharp.Core.ValueOption: System.Type GetType()
+Microsoft.FSharp.Core.ValueOption: T DefaultValue[T](T, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T DefaultWith[T](Microsoft.FSharp.Core.FSharpFunc`2[Microsoft.FSharp.Core.Unit,T], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T GetValue[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T ToObj[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: TState FoldBack[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[TState,TState]], Microsoft.FSharp.Core.FSharpValueOption`1[T], TState)
+Microsoft.FSharp.Core.ValueOption: TState Fold[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[TState,Microsoft.FSharp.Core.FSharpFunc`2[T,TState]], TState, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T[] ToArray[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Void Iterate[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.Unit], Microsoft.FSharp.Core.FSharpValueOption`1[T])
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Boolean Match(System.Object)
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Int32 GetHashCode()
diff --git a/tests/FSharp.Core.UnitTests/SurfaceArea.net40.fs b/tests/FSharp.Core.UnitTests/SurfaceArea.net40.fs
index daebd2d65fed12e4dcae37c49fa8a3b004f4d7c1..16035e67c0277da692547c296e7c06105f9c4693 100644
--- a/tests/FSharp.Core.UnitTests/SurfaceArea.net40.fs
+++ b/tests/FSharp.Core.UnitTests/SurfaceArea.net40.fs
@@ -2272,6 +2272,13 @@ Microsoft.FSharp.Core.FSharpValueOption`1[T]: T Item
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T Value
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T get_Item()
 Microsoft.FSharp.Core.FSharpValueOption`1[T]: T get_Value()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean IsNone
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean IsSome
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean get_IsNone()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Boolean get_IsSome()
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] None
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] Some(T)
+Microsoft.FSharp.Core.FSharpValueOption`1[T]: Microsoft.FSharp.Core.FSharpValueOption`1[T] get_None()
 Microsoft.FSharp.Core.FSharpTypeFunc: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.FSharpTypeFunc: Int32 GetHashCode()
 Microsoft.FSharp.Core.FSharpTypeFunc: System.Object Specialize[T]()
@@ -2870,6 +2877,36 @@ Microsoft.FSharp.Core.OptionModule: TState FoldBack[T,TState](Microsoft.FSharp.C
 Microsoft.FSharp.Core.OptionModule: TState Fold[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[TState,Microsoft.FSharp.Core.FSharpFunc`2[T,TState]], TState, Microsoft.FSharp.Core.FSharpOption`1[T])
 Microsoft.FSharp.Core.OptionModule: T[] ToArray[T](Microsoft.FSharp.Core.FSharpOption`1[T])
 Microsoft.FSharp.Core.OptionModule: Void Iterate[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.Unit], Microsoft.FSharp.Core.FSharpOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean Contains[T](T, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean Equals(System.Object)
+Microsoft.FSharp.Core.ValueOption: Boolean Exists[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean ForAll[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean IsNone[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Boolean IsSome[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Int32 Count[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Int32 GetHashCode()
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Collections.FSharpList`1[T] ToList[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Bind[T,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpValueOption`1[TResult]], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map2[T1,T2,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T1,Microsoft.FSharp.Core.FSharpFunc`2[T2,TResult]], Microsoft.FSharp.Core.FSharpValueOption`1[T1], Microsoft.FSharp.Core.FSharpValueOption`1[T2])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map3[T1,T2,T3,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T1,Microsoft.FSharp.Core.FSharpFunc`2[T2,Microsoft.FSharp.Core.FSharpFunc`2[T3,TResult]]], Microsoft.FSharp.Core.FSharpValueOption`1[T1], Microsoft.FSharp.Core.FSharpValueOption`1[T2], Microsoft.FSharp.Core.FSharpValueOption`1[T3])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[TResult] Map[T,TResult](Microsoft.FSharp.Core.FSharpFunc`2[T,TResult], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] Filter[T](Microsoft.FSharp.Core.FSharpFunc`2[T,System.Boolean], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] Flatten[T](Microsoft.FSharp.Core.FSharpValueOption`1[Microsoft.FSharp.Core.FSharpValueOption`1[T]])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OfNullable[T](System.Nullable`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OfObj[T](T)
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OrElseWith[T](Microsoft.FSharp.Core.FSharpFunc`2[Microsoft.FSharp.Core.Unit,Microsoft.FSharp.Core.FSharpValueOption`1[T]], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Microsoft.FSharp.Core.FSharpValueOption`1[T] OrElse[T](Microsoft.FSharp.Core.FSharpValueOption`1[T], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: System.Nullable`1[T] ToNullable[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: System.String ToString()
+Microsoft.FSharp.Core.ValueOption: System.Type GetType()
+Microsoft.FSharp.Core.ValueOption: T DefaultValue[T](T, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T DefaultWith[T](Microsoft.FSharp.Core.FSharpFunc`2[Microsoft.FSharp.Core.Unit,T], Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T GetValue[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T ToObj[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: TState FoldBack[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.FSharpFunc`2[TState,TState]], Microsoft.FSharp.Core.FSharpValueOption`1[T], TState)
+Microsoft.FSharp.Core.ValueOption: TState Fold[T,TState](Microsoft.FSharp.Core.FSharpFunc`2[TState,Microsoft.FSharp.Core.FSharpFunc`2[T,TState]], TState, Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: T[] ToArray[T](Microsoft.FSharp.Core.FSharpValueOption`1[T])
+Microsoft.FSharp.Core.ValueOption: Void Iterate[T](Microsoft.FSharp.Core.FSharpFunc`2[T,Microsoft.FSharp.Core.Unit], Microsoft.FSharp.Core.FSharpValueOption`1[T])
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Boolean Equals(System.Object)
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Boolean IsDefaultAttribute()
 Microsoft.FSharp.Core.OptionalArgumentAttribute: Boolean Match(System.Object)