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Merged
gusty merged 8 commits into from
Jun 8, 2025
Merged

+ Missing folds #622

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f0ca812
+ Basic tests
gusty Jun 5, 2025
1446d18
Add VOption to ToSeq
gusty Jun 5, 2025
b8e9e7d
Add VOption to Fold
gusty Jun 5, 2025
2a428be
Add VOption to FoldMap and FoldBack
gusty Jun 5, 2025
986fe87
Add VOption to Head and Length
gusty Jun 5, 2025
cd3e033
+ Overloads for Result
gusty Jun 5, 2025
c54b525
Test fold for Result
gusty Jun 6, 2025
af11c83
Update docs
gusty Jun 7, 2025
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3 changes: 2 additions & 1 deletion docsrc/content/abstraction-foldable.fsx
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Expand Up @@ -59,7 +59,8 @@ From .Net/F#
- ``list<'T>``
- ``'T []``
- ``option<'T>``
- ``voption<'T>``
- ``voption<'T>``
- ``Result<'T, 'Error>``
- ``ResizeArray<'T>``
- ``ReadOnlyCollection<'T>``
- ``IReadOnlyCollection<'T>``
Expand Down
84 changes: 60 additions & 24 deletions src/FSharpPlus/Control/Foldable.fs
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Expand Up @@ -42,11 +42,18 @@ open FSharpPlus.Internals.Prelude

type ToSeq =
inherit Default1
static member ToSeq (x: seq<'T> , [<Optional>]_impl: ToSeq) = x
static member ToSeq (x: Text.StringBuilder, _: ToSeq) = string x :> seq<char>
static member ToSeq (x: string , _: ToSeq) = String.toSeq x
static member ToSeq (x: option<'T>, [<Optional>]_impl: ToSeq) = match x with Some x -> Seq.singleton x | _ -> Seq.empty
static member ToSeq (x: Id<'T> , [<Optional>]_impl: ToSeq) = Seq.singleton x.getValue
static member ToSeq (x: seq<'T>, [<Optional>]_impl: ToSeq) =
#if TEST_TRACE
Traces.add "ToSeq seq"
#endif
x

static member ToSeq (x: Text.StringBuilder, _: ToSeq) = string x :> seq<char>
static member ToSeq (x: string , _: ToSeq) = String.toSeq x
static member ToSeq (x: option<'T> , [<Optional>]_impl: ToSeq) = match x with Some x -> Seq.singleton x | _ -> Seq.empty
static member ToSeq (x: voption<'T> , [<Optional>]_impl: ToSeq) = match x with ValueSome x -> Seq.singleton x | _ -> Seq.empty
static member ToSeq (x: Result<'T, _>, [<Optional>]_impl: ToSeq) = match x with Ok x -> Seq.singleton x | _ -> Seq.empty
static member ToSeq (x: Id<'T> , [<Optional>]_impl: ToSeq) = Seq.singleton x.getValue

static member inline Invoke (source: '``Foldable<'T>``) : seq<'T> =
let inline call_2 (a: ^a, b: ^b) = ((^a or ^b) : (static member ToSeq : _*_ -> _) b, a)
Expand All @@ -56,7 +63,13 @@ type ToSeq =
static member inline InvokeOnInstance (source: '``Foldable<'T>``) : seq<'T> = (^``Foldable<'T>``: (static member ToSeq : _ -> _) source)

type ToSeq with
static member inline ToSeq (x: 'S when 'S :> Collections.IEnumerable, [<Optional>]_impl: Default2) = let _f i x : 'T = (^S : (member get_Item : int -> 'T) x, i) in Seq.cast<'T> x : seq<'T>
static member inline ToSeq (x: 'S when 'S :> Collections.IEnumerable, [<Optional>]_impl: Default2) =
#if TEST_TRACE
Traces.add "ToSeq IEnumerable"
#endif
let _f i x : 'T = (^S : (member get_Item : int -> 'T) x, i)
Seq.cast<'T> x : seq<'T>

static member inline ToSeq (x: 'Foldable , [<Optional>]_impl: Default1) = ToSeq.InvokeOnInstance x
static member inline ToSeq (_: 'T when 'T: null and 'T: struct , _: Default1) = ()

Expand Down Expand Up @@ -99,16 +112,22 @@ type ToArray =

type FoldBack =
inherit Default1
static member inline FoldBack (x: 'F , f: 'a->'b->'b, z: 'b , [<Optional>]_impl: Default2) = List.foldBack f (ToList.Invoke x) z
static member inline FoldBack (x: 'F, f: 'a -> 'b -> 'b, z: 'b, [<Optional>]_impl: Default2) =
#if TEST_TRACE
Traces.add "Foldback Default"
#endif
List.foldBack f (ToList.Invoke x) z
static member inline FoldBack (x: 'F , f: 'a->'b->'b, z: 'b , [<Optional>]_impl: Default1) = (^F : (static member FoldBack : ^F -> _ -> _-> ^b) x, f, z)
static member FoldBack (x: seq<_> , f , z , [<Optional>]_impl: FoldBack) = List.foldBack f (Seq.toList x) z
static member FoldBack (x: option<_> , f , z , [<Optional>]_impl: FoldBack) = match x with Some x -> f x z | _ -> z
static member FoldBack (x: seq<_> , f , z , [<Optional>]_impl: FoldBack) = List.foldBack f (Seq.toList x) z
static member FoldBack (x: option<_> , f , z , [<Optional>]_impl: FoldBack) = match x with Some x -> f x z | _ -> z
static member FoldBack (x: voption<_> , f , z , [<Optional>]_impl: FoldBack) = match x with ValueSome x -> f x z | _ -> z
static member FoldBack (x: Result<_, _> , f , z , [<Optional>]_impl: FoldBack) = match x with Ok x -> f x z | _ -> z
static member FoldBack (x: list<_> , f , z , [<Optional>]_impl: FoldBack) = List.foldBack f x z
static member FoldBack (x: _ [] , f , z , [<Optional>]_impl: FoldBack) = Array.foldBack f x z
static member FoldBack (x: Set<_> , f , z , [<Optional>]_impl: FoldBack) = Set.foldBack f x z
static member FoldBack (x: _ ResizeArray, f , z , [<Optional>]_impl: FoldBack) = Array.foldBack f (x.ToArray ()) z
static member FoldBack (x: string , f , z , [<Optional>]_impl: FoldBack) = Array.foldBack f (x.ToCharArray ()) z
static member FoldBack (x: StringBuilder, f , z , [<Optional>]_impl: FoldBack) = Array.foldBack f (x.ToString().ToCharArray ()) z
static member FoldBack (x: StringBuilder, f , z , [<Optional>]_impl: FoldBack) = Array.foldBack f (x.ToString().ToCharArray ()) z
static member FoldBack (x: Id<'a> , f , z , [<Optional>]_impl: FoldBack) = f x.getValue z

static member inline Invoke (folder: 'T->'State->'State) (state: 'State) (foldable: '``Foldable'<T>``) : 'State =
Expand All @@ -122,18 +141,24 @@ type FoldMap =

static member inline FromFoldFoldBack f x = FoldBack.Invoke (Plus.Invoke << f) (Zero.Invoke ()) x

static member inline FoldMap (x: option<_>, f, [<Optional>]_impl: FoldMap ) = match x with Some x -> f x | _ -> Zero.Invoke ()
static member inline FoldMap (x: list<_> , f, [<Optional>]_impl: FoldMap ) = List.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: Set<_> , f, [<Optional>]_impl: FoldMap ) = Seq.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: _ [] , f, [<Optional>]_impl: FoldMap ) = Array.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: option<_> , f, [<Optional>]_impl: FoldMap) = match x with Some x -> f x | _ -> Zero.Invoke ()
static member inline FoldMap (x: voption<_> , f, [<Optional>]_impl: FoldMap) = match x with ValueSome x -> f x | _ -> Zero.Invoke ()
static member inline FoldMap (x: Result<_, _>, f, [<Optional>]_impl: FoldMap) = match x with Ok x -> f x | _ -> Zero.Invoke ()
static member inline FoldMap (x: list<_> , f, [<Optional>]_impl: FoldMap) = List.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: Set<_> , f, [<Optional>]_impl: FoldMap) = Seq.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: _ [] , f, [<Optional>]_impl: FoldMap) = Array.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x

static member inline Invoke (f: 'T->'Monoid) (x: '``Foldable'<T>``) : 'Monoid =
let inline call_2 (a: ^a, b: ^b, f) = ((^a or ^b) : (static member FoldMap : _*_*_ -> _) b, f, a)
let inline call (a: 'a, b: 'b, f) = call_2 (a, b, f)
call (Unchecked.defaultof<FoldMap>, x, f)

type FoldMap with
static member inline FoldMap (x: seq<_> , f, [<Optional>]_impl: Default2) = Seq.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x: seq<_> , f, [<Optional>]_impl: Default2) =
#if TEST_TRACE
Traces.add "FoldMap Default"
#endif
Seq.fold (fun x y -> Plus.Invoke x (f y)) (Zero.Invoke ()) x
static member inline FoldMap (x , f, [<Optional>]_impl: Default1) = (^F : (static member FoldMap : ^F -> _ -> _) x, f)
static member inline FoldMap (_: ^t when ^t: null and ^t: struct, _, _: Default1) = ()

Expand All @@ -146,14 +171,21 @@ type Fold =

static member inline FromFoldMap f z t = let (f: _Dual<_Endo<'t>>) = FoldMap.Invoke (_Dual << _Endo << flip f) t in f.Value.Value z

static member inline Fold (x , f, z, [<Optional>]_impl: Default2) = Seq.fold f z (ToSeq.Invoke x)
static member inline Fold (x: 'F , f: 'b->'a->'b, z: 'b, [<Optional>]_impl: Default1) = (^F : (static member Fold : ^F -> _ -> _-> ^b) x, f, z)
static member Fold (x: option<_>, f, z , [<Optional>]_impl: Fold ) = match x with Some x -> f z x | _ -> z
static member Fold (x: Id<_> , f, z , [<Optional>]_impl: Fold ) = f z x.getValue
static member Fold (x: seq<_> , f, z , [<Optional>]_impl: Fold ) = Seq.fold f z x
static member Fold (x: list<_> , f, z , [<Optional>]_impl: Fold ) = List.fold f z x
static member Fold (x: Set<_> , f, z , [<Optional>]_impl: Fold ) = Set.fold f z x
static member Fold (x: _ [] , f, z , [<Optional>]_impl: Fold ) = Array.fold f z x
static member inline Fold (x , f, z, [<Optional>]_impl: Default2) =
#if TEST_TRACE
Traces.add "Fold Default"
#endif
Seq.fold f z (ToSeq.Invoke x)

static member inline Fold (x: 'F , f: 'b->'a->'b, z: 'b, [<Optional>]_impl: Default1) = (^F : (static member Fold : ^F -> _ -> _-> ^b) x, f, z)
static member Fold (x: option<_> , f, z , [<Optional>]_impl: Fold ) = match x with Some x -> f z x | _ -> z
static member Fold (x: voption<_> , f, z , [<Optional>]_impl: Fold ) = match x with ValueSome x -> f z x | _ -> z
static member Fold (x: Result<_, _>, f, z , [<Optional>]_impl: Fold ) = match x with Ok x -> f z x | _ -> z
static member Fold (x: Id<_> , f, z , [<Optional>]_impl: Fold ) = f z x.getValue
static member Fold (x: seq<_> , f, z , [<Optional>]_impl: Fold ) = Seq.fold f z x
static member Fold (x: list<_> , f, z , [<Optional>]_impl: Fold ) = List.fold f z x
static member Fold (x: Set<_> , f, z , [<Optional>]_impl: Fold ) = Set.fold f z x
static member Fold (x: _ [] , f, z , [<Optional>]_impl: Fold ) = Array.fold f z x

static member inline Invoke (folder: 'State->'T->'State) (state: 'State) (foldable: '``Foldable'<T>``) : 'State =
let inline call_2 (a: ^a, b: ^b, f, z) = ((^a or ^b) : (static member Fold : _*_*_*_ -> _) b, f, z, a)
Expand All @@ -170,7 +202,7 @@ type Exists =
static member Exists (x: 'a [] , f , [<Optional>]_impl: Exists ) = Array.exists f x
static member Exists (x: Set<'a> , f , [<Optional>]_impl: Exists ) = Set.exists f x
static member Exists (x: 'a ResizeArray , f , [<Optional>]_impl: Exists ) = Seq.exists f x
static member Exists (x: string , f , [<Optional>]_impl: Exists ) = String.exists f x
static member Exists (x: string , f , [<Optional>]_impl: Exists ) = String.exists f x
static member Exists (x: StringBuilder , f , [<Optional>]_impl: Exists ) = x |> string |> String.exists f

static member inline Invoke (predicate: 'T->bool) (source: '``Foldable'<T>``) =
Expand Down Expand Up @@ -231,6 +263,8 @@ type Head =
static member inline Head (x: '``Foldable<'T>``, [<Optional>]_impl: Default2) = Seq.head (ToSeq.Invoke x) : 'T
static member inline Head (x: '``Foldable<'T>``, [<Optional>]_impl: Default1) = (^``Foldable<'T>`` : (member Head : 'T) x)
static member Head (x: 'T option , [<Optional>]_impl: Head ) = x.Value
static member Head (x: 'T voption , [<Optional>]_impl: Head ) = x.Value
static member Head (x: Result<_, _> , [<Optional>]_impl: Head ) = Result.get x
static member Head (x: 'T [] , [<Optional>]_impl: Head ) = x.[0]
static member Head (x: NonEmptySeq<'T> , [<Optional>]_impl: Head ) = x.First
static member Head (x: Id<'T> , [<Optional>]_impl: Head ) = x.getValue
Expand Down Expand Up @@ -390,6 +424,8 @@ type Length =
static member Length (x: ResizeArray<'T> , [<Optional>]_impl: Length ) = x.Count
static member Length (x: 'T list , [<Optional>]_impl: Length ) = List.length x
static member Length (x: option<'T> , [<Optional>]_impl: Length ) = if x.IsSome then 1 else 0
static member Length (x: voption<'T> , [<Optional>]_impl: Length ) = if x.IsSome then 1 else 0
static member Length (x: Result<_, _> , [<Optional>]_impl: Length ) = if Result.isOk x then 1 else 0
static member Length (x: 'T [] , [<Optional>]_impl: Length ) = Array.length x

static member inline Invoke (source: '``Foldable<'T>``) =
Expand Down
1 change: 1 addition & 0 deletions tests/FSharpPlus.Tests/FSharpPlus.Tests.fsproj
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Expand Up @@ -22,6 +22,7 @@
<Compile Include="Splits.fs" />
<Compile Include="Monoid.fs" />
<Compile Include="Parsing.fs" />
<Compile Include="Folds.fs" />
<Compile Include="Traversals.fs" />
<Compile Include="Indexables.fs" />
<Compile Include="Collections.fs" />
Expand Down
38 changes: 38 additions & 0 deletions tests/FSharpPlus.Tests/Folds.fs
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@@ -0,0 +1,38 @@
namespace FSharpPlus.Tests

#nowarn "686"

open System
open System.Collections.ObjectModel
open FSharpPlus
open FSharpPlus.Data
open FSharpPlus.Control
open NUnit.Framework
open Helpers
open FSharpPlus.Math.Applicative
open CSharpLib
open System.Threading.Tasks
#if TEST_TRACE
open FSharpPlus.Internals
#endif

module Folds =

[<Test>]
let basicFolds () =
#if TEST_TRACE
Traces.reset()
#endif
let r1 = set [1..3] |> fold (+) 0
let r2 = set [1..3] |> toSeq
let r3 = ValueSome 1 |> toSeq
let r4 = ValueSome 1 |> fold (+) 0
let r5 = Ok 1 |> fold (+) 0
Assert.AreEqual (6, r1)
CollectionAssert.AreEqual ([1; 2; 3], r2)
CollectionAssert.AreEqual ([1], r3)
Assert.AreEqual (1, r4)
Assert.AreEqual (1, r5)
#if TEST_TRACE
CollectionAssert.AreEqual (["ToSeq seq"], Traces.get())
#endif
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