Fix #491

src/Fantomas.Tests/FunctionDefinitionTests.fs

@@ -144,7 +144,7 @@ let ``should keep whitespace after function call``() =
 [<Test>]
 let ``should keep type annotations``() =
     formatSourceString false """let empty<'T> : LazyList<'T> = EmptyValue<'T>.Value""" config
-    |> should equal """let empty<'T>: LazyList<'T> = EmptyValue<'T>.Value
+    |> should equal """let empty<'T> : LazyList<'T> = EmptyValue<'T>.Value
 """
 
 [<Test>]

src/Fantomas.Tests/LetBindingTests.fs

@@ -270,4 +270,11 @@ let someFun someReallyLoooooooooooooooongValue =
     someOtherFun 1 3
 
     someOtherOtherFun 2 4
-"""
+"""
+
+[<Test>]
+let ``should keep space before :`` () =
+    formatSourceString false "let refl<'a> : Teq<'a, 'a> = Teq(id,   id)" config
+    |> fun formatted -> formatSourceString false formatted config
+    |> should equal "let refl<'a> : Teq<'a, 'a> = Teq(id, id)
+"

src/Fantomas/CodePrinter.fs

@@ -440,8 +440,19 @@ and genExprSepEqPrependType astContext prefix (pat:SynPat) e ctx =
         | MatchLambda _ -> false
         | _ -> futureNlnCheck (genExpr astContext e) ctx
     match e with
-    | TypedExpr(Typed, e, t) -> (prefix +> sepColon +> genType astContext false t +> sepEq
-                                +> breakNlnOrAddSpace astContext (multilineCheck || checkPreserveBreakForExpr e ctx) e) ctx
+    | TypedExpr(Typed, e, t) ->
+        let addExtraSpaceBeforeGenericType (ctx: Context) =
+            match pat with
+            | SynPat.LongIdent(_, _, Some(SynValTyparDecls(_)), _, _, _) when (not ctx.Config.SpaceBeforeColon) ->
+                let dump = (dump ctx).ToCharArray()
+                match Array.tryLast dump with
+                | Some('>') -> sepSpace
+                | _ -> sepNone
+            | _ -> sepNone
+            <| ctx
+
+        (prefix +> addExtraSpaceBeforeGenericType +> sepColon +> genType astContext false t +> sepEq
+        +> breakNlnOrAddSpace astContext (multilineCheck || checkPreserveBreakForExpr e ctx) e) ctx
     | e ->
         let hasCommentAfterEqual =
             ctx.Trivia
@@ -481,6 +492,7 @@ and genLetBinding astContext pref b =
             +> opt sepSpace ao genAccess
             +> ifElse isMutable (!- "mutable ") sepNone +> ifElse isInline (!- "inline ") sepNone
             +> genPat astContext p
+            +> dumpAndContinue
 
         genExprSepEqPrependType astContext prefix p e
 

src/Fantomas/SourceParser.fs

@@ -447,8 +447,6 @@ let (|DoBinding|LetBinding|MemberBinding|PropertyBinding|ExplicitCtor|) = functi
         DoBinding(ats, px, expr)
     | SynBinding.Binding(ao, _, isInline, isMutable, attrs, px, _, pat, _, expr, _, _) ->
         LetBinding(attrs, px, ao, isInline, isMutable, pat, expr)
-
-let (|BindingReturnInfo|) (SynBindingReturnInfo (t, _, ats)) = (ats, t)
 
 // Expressions (55 cases, lacking to handle 11 cases)
 

src/Fantomas/Trivia.fs

@@ -366,5 +366,4 @@ let collectTrivia config tokens lineCount (ast: ParsedInput) =
     | [] -> []
     | _ ->
         List.fold addTriviaToTriviaNode triviaNodes trivias
-        |> List.filter (triviaNodeIsNotEmpty) // only keep nodes where something special needs to happen.
-    |> Dbg.teePrint
+        |> List.filter (triviaNodeIsNotEmpty) // only keep nodes where something special needs to happen.