Fix builder bind (#69)

* Fix builder bind

src/Builder.fs

@@ -31,29 +31,20 @@ type RequestBuilder () =
     /// Binds value of 'TValue for let! All handlers runs in same context within the builder.
     member _.Bind
         (
-            source: HttpHandler<'TSource, 'TNext>,
-            fn: 'TNext -> HttpHandler<'TNext, 'TResult>
+            source: HttpHandler<'TSource, 'TValue>,
+            fn: 'TValue -> HttpHandler<'TSource, 'TResult>
         ): HttpHandler<'TSource, 'TResult> =
 
         let subscribe (next: IHttpNext<'TResult>) =
-            let (next: IHttpNext<'TNext>) =
-                { new IHttpNext<'TNext> with
+            let next =
+                { new IHttpNext<'TValue> with
                     member _.NextAsync(ctx, ?content) =
                         task {
-                            let obv =
-                                { new IHttpNext<'TResult> with
-                                    member _.NextAsync(ctx', content) = next.NextAsync(ctx, ?content = content)
-                                    member _.ErrorAsync(ctx, exn) = next.ErrorAsync(ctx, exn)
-                                }
-
                             match content with
                             | Some content ->
-                                let res = fn content
-
-                                return!
-                                    res.Subscribe(obv)
-                                    |> (fun obv -> obv.NextAsync(ctx, content = content))
-                            | None -> return! obv.NextAsync(ctx)
+                                let bound: HttpHandler<'TSource, 'TResult> = fn content
+                                return! bound.Subscribe(next).NextAsync(ctx)
+                            | None -> return! next.NextAsync(ctx)
                         }
 
                     member _.ErrorAsync(ctx, exn) = next.ErrorAsync(ctx, exn)

src/Context.fs

@@ -267,21 +267,21 @@ module Context =
         }
 
     /// Merge the list of context objects. Used by the sequential and concurrent HTTP handlers.
-    let merge (context: List<Context>): Context =
+    let merge (ctxs: List<Context>): Context =
+        let ctxs =
+            match ctxs with
+            | [] -> [ defaultContext ]
+            | _ -> ctxs
+
         // Use the max status code.
         let statusCode =
-            let codes =
-                context
-                |> List.map (fun ctx -> ctx.Response.StatusCode)
-
-            if codes.IsEmpty then
-                HttpStatusCode.NotFound
-            else
-                List.max codes
+            ctxs
+            |> List.map (fun ctx -> ctx.Response.StatusCode)
+            |> List.max
 
         // Concat the reason phrases (if they are different)
         let reasonPhrase =
-            context
+            ctxs
             |> List.map (fun ctx -> ctx.Response.ReasonPhrase)
             |> List.distinct
             |> String.concat ", "
@@ -297,18 +297,17 @@ module Context =
 
         // Merge headers
         let headers =
-            context
+            ctxs
             |> List.map (fun ctx -> ctx.Response.Headers)
             |> List.fold
                 (fun state hdr -> merge state hdr (fun k (a, b) -> if a = b then a else Seq.append a b))
                 Map.empty
 
         {
             Request =
-                context
-                |> List.tryHead
-                |> Option.map (fun ctx -> ctx.Request)
-                |> Option.defaultValue defaultRequest
+                ctxs
+                |> Seq.map (fun ctx -> ctx.Request)
+                |> Seq.head
             Response =
                 {
                     Headers = headers

test/Builder.fs

@@ -31,7 +31,7 @@ let ``Simple unit handler in builder is Ok`` () =
         let! result =
             let a =
                 req {
-                    let! value = unit 42
+                    let! value = singleton 42
                     return value
                 }
 
@@ -47,10 +47,10 @@ let ``Simple return from unit handler in builder is Ok`` () =
         // Arrange
         let ctx = Context.defaultContext
 
-        let a = unit 42 |> runAsync ctx
+        let a = singleton 42 |> runAsync ctx
 
         // Act
-        let! result = req { return! unit 42 } |> runUnsafeAsync ctx
+        let! result = req { return! singleton 42 } |> runUnsafeAsync ctx
 
         // Assert
         test <@ result = 42 @>
@@ -65,8 +65,8 @@ let ``Multiple handlers in builder is Ok`` () =
         // Act
         let request =
             req {
-                let! a = unit 10
-                let! b = unit 20
+                let! a = singleton 10
+                let! b = singleton 20
                 return! add a b
             }
 

test/Common.fs

@@ -60,16 +60,16 @@ type HttpMessageHandlerStub (NextAsync: Func<HttpRequestMessage, CancellationTok
         ): Task<HttpResponseMessage> =
         task { return! NextAsync.Invoke(request, cancellationToken) }
 
-let unit<'TSource, 'TResult> (value: 'TResult): HttpHandler<'TSource, 'TResult> =
+let singleton<'TSource, 'TResult> (value: 'TResult): HttpHandler<'TSource, 'TResult> =
     HttpHandler
     <| fun next ->
         { new IHttpNext<'TSource> with
-            member _.NextAsync(ctx, ?content) = next.NextAsync(ctx, value)
+            member _.NextAsync(ctx, _) = next.NextAsync(ctx, value)
             member _.ErrorAsync(ctx, exn) = next.ErrorAsync(ctx, exn)
         }
 
 
-let add (a: int) (b: int) = unit (a + b)
+let add (a: int) (b: int) = singleton (a + b)
 
 
 exception TestException of code: int * message: string with

test/Handler.fs

@@ -22,7 +22,7 @@ let ``Simple unit handler is Ok`` () =
         let ctx = Context.defaultContext
 
         // Act
-        let! content = unit 42 >=> unit 43 |> runUnsafeAsync ctx
+        let! content = singleton 42 >=> singleton 43 |> runUnsafeAsync ctx
 
         // Assert
         test <@ content = 43 @>
@@ -50,7 +50,7 @@ let ``Simple error then ok is Error`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = error "failed" >=> unit 42
+        let req = error "failed" >=> singleton 42
 
         // Act
         let! result = req |> runAsync ctx
@@ -68,7 +68,7 @@ let ``Simple ok then error is Error`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = unit 42 >=> error "failed"
+        let req = singleton 42 >=> error "failed"
 
         // Act
         let! result = req |> runAsync ctx
@@ -87,7 +87,7 @@ let ``Catching ok is Ok`` () =
         let errorHandler = badRequestHandler 420
 
         let req =
-            unit 42
+            singleton 42
             >=> map (fun a -> a * 10)
             >=> catch errorHandler
 
@@ -105,7 +105,7 @@ let ``Catching errors is Ok`` () =
         let ctx = Context.defaultContext
         let errorHandler = badRequestHandler 420
 
-        let req = unit 42 >=> error "failed" >=> catch errorHandler
+        let req = singleton 42 >=> error "failed" >=> catch errorHandler
 
         // Act
         let! content = req |> runUnsafeAsync ctx
@@ -121,7 +121,7 @@ let ``Not catching errors is Error`` () =
         let ctx = Context.defaultContext
         let errorHandler = badRequestHandler 420
 
-        let req = unit 42 >=> catch errorHandler >=> error "failed"
+        let req = singleton 42 >=> catch errorHandler >=> error "failed"
 
         // Act
         let! result = req |> runAsync ctx
@@ -137,7 +137,7 @@ let ``Sequential handlers is Ok`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = sequential [ unit 1; unit 2; unit 3; unit 4; unit 5 ]
+        let req = sequential [ singleton 1; singleton 2; singleton 3; singleton 4; singleton 5 ]
 
         // Act
         let! content = req |> runUnsafeAsync ctx
@@ -151,7 +151,7 @@ let ``Sequential handlers with an Error is Error`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = sequential [ unit 1; unit 2; error "fail"; unit 4; unit 5 ]
+        let req = sequential [ singleton 1; singleton 2; error "fail"; singleton 4; singleton 5 ]
 
         // Act
         let! result = req |> runAsync ctx
@@ -169,7 +169,7 @@ let ``Concurrent handlers is Ok`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = concurrent [ unit 1; unit 2; unit 3; unit 4; unit 5 ]
+        let req = concurrent [ singleton 1; singleton 2; singleton 3; singleton 4; singleton 5 ]
 
         // Act
         let! result = req |> runAsync ctx
@@ -187,7 +187,7 @@ let ``Concurrent handlers with an Error is Error`` () =
     task {
         // Arrange
         let ctx = Context.defaultContext
-        let req = concurrent [ unit 1; unit 2; error "fail"; unit 4; unit 5 ]
+        let req = concurrent [ singleton 1; singleton 2; error "fail"; singleton 4; singleton 5 ]
 
         // Act
         let! result = req |> runAsync ctx
@@ -207,7 +207,7 @@ let ``Chunked handlers is Ok`` (PositiveInt chunkSize) (PositiveInt maxConcurren
         let ctx = Context.defaultContext
 
         let req =
-            chunk<unit, int, int> chunkSize maxConcurrency unit [ 1; 2; 3; 4; 5 ]
+            chunk<unit, int, int> chunkSize maxConcurrency singleton [ 1; 2; 3; 4; 5 ]
 
         // Act
         let! result = req |> runUnsafeAsync ctx
@@ -220,7 +220,7 @@ let ``Choose handlers is Ok`` =
         // Arrange
         let ctx = Context.defaultContext
 
-        let req = choose [ error "1"; unit 2; error "3"; unit 4 ]
+        let req = choose [ error "1"; singleton 2; error "3"; singleton 4 ]
 
         // Act
         let! result = req |> runUnsafeAsync ctx
@@ -258,7 +258,7 @@ let ``Request with token renewer without token gives error`` () =
         let renewer _ = err |> Error |> Task.FromResult
         let ctx = Context.defaultContext
 
-        let req = withTokenRenewer renewer >=> unit 42
+        let req = withTokenRenewer renewer >=> singleton 42
 
         // Act
         let! result = req |> runAsync ctx
@@ -276,7 +276,7 @@ let ``Request with token renewer throws exception gives error`` () =
         let renewer _ = failwith "failing" |> Task.FromResult
         let ctx = Context.defaultContext
 
-        let req = withTokenRenewer renewer >=> unit 42
+        let req = withTokenRenewer renewer >=> singleton 42
 
         // Act
         let! result = req |> runAsync ctx