feat: rework encoder API to not need a custom DU (#188)

* Change Encoder type to return IEncodable, deferring concrete representation

* Change rec to inline

* style: remove some parentheses and alias `this` to `_` if not needed

[core]

* fix: fix `encodeList` and `encodeSeq`

[python]

* chore: update changelog files

---------

Co-authored-by: Maxime Mangel <mangel.maxime@protonmail.com>

packages/Thoth.Json.Core/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+* Rework encoder API to not need a custom DU ([GH-188](https://github.com/thoth-org/Thoth.Json/pull/188/))
+
 ## 0.2.1 - 2023-12-12
 
 ### Fixed

packages/Thoth.Json.Core/Encode.fs

@@ -7,24 +7,76 @@ open System
 [<RequireQualifiedAccess>]
 module Encode =
 
-    let inline string value = Json.String value
-    let inline char value = Json.Char value
+    let inline string value =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeString value
+        }
+
+    let inline char value =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeChar value
+        }
+
     let inline guid value = value.ToString() |> string
-    let inline float value = Json.DecimalNumber value
 
-    let float32 (value: float32) =
-        Json.DecimalNumber(Operators.float value)
+    let inline float value =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeDecimalNumber value
+        }
+
+    let float32 (value: float32) = float (Operators.float value)
 
     let inline decimal (value: decimal) =
         value.ToString(CultureInfo.InvariantCulture) |> string
 
-    let inline nil<'T> = Json.Null
-    let inline bool value = Json.Boolean value
-    let inline object values = Json.Object values
-    let inline array values = Json.Array values
-    let list values = Json.Array(values |> List.toArray)
-    let seq values = Json.Array(values |> Seq.toArray)
-    let dict (values: Map<string, Json>) : Json = values |> Map.toList |> object
+    let inline nil<'T> =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeNull ()
+        }
+
+    let inline bool value =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeBool value
+        }
+
+    let inline object (values: seq<string * IEncodable>) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                let o = helpers.createEmptyObject ()
+
+                for k, v in values do
+                    let ve = v.Encode(helpers)
+                    helpers.setPropertyOnObject (o, k, ve)
+
+                o
+        }
+
+    let inline array (values: IEncodable array) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                values
+                |> Array.map (fun v -> v.Encode(helpers))
+                |> helpers.encodeArray
+        }
+
+    let list (values: IEncodable list) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                values
+                |> List.map (fun v -> v.Encode(helpers))
+                |> helpers.encodeList
+        }
+
+    let seq (values: IEncodable seq) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                values
+                |> Seq.map (fun v -> v.Encode(helpers))
+                |> helpers.encodeSeq
+        }
+
+    let dict (values: Map<string, IEncodable>) : IEncodable =
+        values |> Map.toSeq |> object
 
     let inline bigint (value: bigint) = value.ToString() |> string
 
@@ -36,22 +88,50 @@ module Encode =
     let inline datetime (value: DateTime) =
         value.ToString("O", CultureInfo.InvariantCulture) |> string
 
-    let inline sbyte (value: sbyte) = Json.IntegralNumber(uint32 value)
-    let inline byte (value: byte) = Json.IntegralNumber(uint32 value)
-    let inline int16 (value: int16) = Json.IntegralNumber(uint32 value)
-    let inline uint16 (value: uint16) = Json.IntegralNumber(uint32 value)
-    let inline int (value: int) = Json.IntegralNumber(uint32 value)
-    let inline uint32 (value: uint32) = Json.IntegralNumber value
+    let inline sbyte (value: sbyte) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                helpers.encodeIntegralNumber (uint32 value)
+        }
+
+    let inline byte (value: byte) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                helpers.encodeIntegralNumber (uint32 value)
+        }
+
+    let inline int16 (value: int16) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                helpers.encodeIntegralNumber (uint32 value)
+        }
+
+    let inline uint16 (value: uint16) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                helpers.encodeIntegralNumber (uint32 value)
+        }
+
+    let inline int (value: int) =
+        { new IEncodable with
+            member _.Encode(helpers) =
+                helpers.encodeIntegralNumber (uint32 value)
+        }
+
+    let inline uint32 (value: uint32) =
+        { new IEncodable with
+            member _.Encode(helpers) = helpers.encodeIntegralNumber (value)
+        }
 
     let inline int64 (value: int64) =
         value.ToString(CultureInfo.InvariantCulture) |> string
 
     let inline uint64 (value: uint64) =
         value.ToString(CultureInfo.InvariantCulture) |> string
 
-    let inline unit () = Json.Unit
+    let inline unit () = nil
 
-    let tuple2 (enc1: Encoder<'T1>) (enc2: Encoder<'T2>) (v1, v2) : Json =
+    let tuple2 (enc1: Encoder<'T1>) (enc2: Encoder<'T2>) (v1, v2) : IEncodable =
         array
             [|
                 enc1 v1
@@ -63,7 +143,7 @@ module Encode =
         (enc2: Encoder<'T2>)
         (enc3: Encoder<'T3>)
         (v1, v2, v3)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -78,7 +158,7 @@ module Encode =
         (enc3: Encoder<'T3>)
         (enc4: Encoder<'T4>)
         (v1, v2, v3, v4)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -95,7 +175,7 @@ module Encode =
         (enc4: Encoder<'T4>)
         (enc5: Encoder<'T5>)
         (v1, v2, v3, v4, v5)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -114,7 +194,7 @@ module Encode =
         (enc5: Encoder<'T5>)
         (enc6: Encoder<'T6>)
         (v1, v2, v3, v4, v5, v6)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -135,7 +215,7 @@ module Encode =
         (enc6: Encoder<'T6>)
         (enc7: Encoder<'T7>)
         (v1, v2, v3, v4, v5, v6, v7)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -158,7 +238,7 @@ module Encode =
         (enc7: Encoder<'T7>)
         (enc8: Encoder<'T8>)
         (v1, v2, v3, v4, v5, v6, v7, v8)
-        : Json
+        : IEncodable
         =
         array
             [|
@@ -177,7 +257,7 @@ module Encode =
         (keyEncoder: Encoder<'key>)
         (valueEncoder: Encoder<'value>)
         (values: Map<'key, 'value>)
-        : Json
+        : IEncodable
         =
         values
         |> Map.toList
@@ -190,44 +270,41 @@ module Encode =
 
     module Enum =
 
-        let byte<'TEnum when 'TEnum: enum<byte>> (value: 'TEnum) : Json =
+        let byte<'TEnum when 'TEnum: enum<byte>> (value: 'TEnum) : IEncodable =
             LanguagePrimitives.EnumToValue value |> byte
 
-        let sbyte<'TEnum when 'TEnum: enum<sbyte>> (value: 'TEnum) : Json =
+        let sbyte<'TEnum when 'TEnum: enum<sbyte>>
+            (value: 'TEnum)
+            : IEncodable
+            =
             LanguagePrimitives.EnumToValue value |> sbyte
 
-        let int16<'TEnum when 'TEnum: enum<int16>> (value: 'TEnum) : Json =
+        let int16<'TEnum when 'TEnum: enum<int16>>
+            (value: 'TEnum)
+            : IEncodable
+            =
             LanguagePrimitives.EnumToValue value |> int16
 
-        let uint16<'TEnum when 'TEnum: enum<uint16>> (value: 'TEnum) : Json =
+        let uint16<'TEnum when 'TEnum: enum<uint16>>
+            (value: 'TEnum)
+            : IEncodable
+            =
             LanguagePrimitives.EnumToValue value |> uint16
 
-        let int<'TEnum when 'TEnum: enum<int>> (value: 'TEnum) : Json =
+        let int<'TEnum when 'TEnum: enum<int>> (value: 'TEnum) : IEncodable =
             LanguagePrimitives.EnumToValue value |> int
 
-        let uint32<'TEnum when 'TEnum: enum<uint32>> (value: 'TEnum) : Json =
+        let uint32<'TEnum when 'TEnum: enum<uint32>>
+            (value: 'TEnum)
+            : IEncodable
+            =
             LanguagePrimitives.EnumToValue value |> uint32
 
-    let option (encoder: 'a -> Json) =
+    let option (encoder: Encoder<'a>) =
         Option.map encoder >> Option.defaultWith (fun _ -> nil)
 
-    let rec toJsonValue (helpers: IEncoderHelpers<'JsonValue>) (json: Json) =
-        match json with
-        | Json.String value -> helpers.encodeString value
-        | Json.IntegralNumber value -> helpers.encodeIntegralNumber value
-        | Json.Object values ->
-            let o = helpers.createEmptyObject ()
-
-            values
-            |> Seq.iter (fun (k, v) ->
-                helpers.setPropertyOnObject (o, k, toJsonValue helpers v)
-            )
-
-            o
-        | Json.Char value -> helpers.encodeChar value
-        | Json.DecimalNumber value -> helpers.encodeDecimalNumber value
-        | Json.Null -> helpers.encodeNull ()
-        | Json.Boolean value -> helpers.encodeBool value
-        | Json.Array value ->
-            value |> Array.map (toJsonValue helpers) |> helpers.encodeArray
-        | Json.Unit -> helpers.encodeNull ()
+    let inline toJsonValue
+        (helpers: IEncoderHelpers<'JsonValue>)
+        (json: IEncodable)
+        =
+        json.Encode(helpers)

packages/Thoth.Json.Core/Types.fs

@@ -73,4 +73,9 @@ type Json =
     | IntegralNumber of uint32
     | Unit
 
-type Encoder<'T> = 'T -> Json
+type IEncodable =
+    abstract member Encode<'JsonValue> :
+        helpers: IEncoderHelpers<'JsonValue> ->
+            'JsonValue
+
+type Encoder<'T> = 'T -> IEncodable

packages/Thoth.Json.JavaScript/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+* Rework encoder API to not need a custom DU ([GH-188](https://github.com/thoth-org/Thoth.Json/pull/188/))
+
 ### Added
 
 * `Decode.unsafeFromString`

packages/Thoth.Json.JavaScript/Encode.fs

@@ -27,6 +27,6 @@ module Encode =
             member _.encodeIntegralNumber value = box value
         }
 
-    let toString (space: int) (value: Json) : string =
+    let toString (space: int) (value: IEncodable) : string =
         let json = Encode.toJsonValue helpers value
         JS.JSON.stringify (json, space = space)

packages/Thoth.Json.Newtonsoft/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+* Rework encoder API to not need a custom DU ([GH-188](https://github.com/thoth-org/Thoth.Json/pull/188/))
+
 ### Added
 
 * `Decode.unsafeFromString`

packages/Thoth.Json.Newtonsoft/Encode.fs

@@ -37,7 +37,7 @@ module Encode =
                 JValue(uint64 value)
         }
 
-    let toString (space: int) (value: Json) : string =
+    let toString (space: int) (value: IEncodable) : string =
         let format =
             if space = 0 then
                 Formatting.None

packages/Thoth.Json.Python/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Changed
+
+* Rework encoder API to not need a custom DU ([GH-188](https://github.com/thoth-org/Thoth.Json/pull/188/))
+
 ## 0.2.0 - 2024-04-03
 
 ### Added

packages/Thoth.Json.Python/Encode.fs

@@ -21,13 +21,17 @@ module Encode =
                 o?(key) <- value
 
             member _.encodeArray values = values
-            member _.encodeList values = JS.Constructors.Array.from values
-            member _.encodeSeq values = JS.Constructors.Array.from values
+
+            member this.encodeList values =
+                values |> List.toArray |> this.encodeArray
+
+            member this.encodeSeq values =
+                values |> Seq.toArray |> this.encodeArray
 
             member _.encodeIntegralNumber value = box value
         }
 
-    let toString (space: int) (value: Json) : string =
+    let toString (space: int) (value: IEncodable) : string =
         let json = Encode.toJsonValue helpers value
         // If we pass an indention of 0 to Python's json.dumps, it will
         // insert newlines, between each element instead of compressing

tests/Thoth.Json.Tests/Util.fs

@@ -25,7 +25,7 @@ open Thoth.Json.Core
 //     abstract
 
 type IEncode =
-    abstract toString: int -> Json -> string
+    abstract toString: int -> IEncodable -> string
 
 type IDecode =
     abstract fromString<'T> : Decoder<'T> -> string -> Result<'T, string>