Scala gen enhancements (#143)

* Fix elm-syntax version in CLI.

* Fix elm-syntax operator precedence.

* Use better literal wrappers in generated Scala.

* Generate case objects for no-argument type constructors. #105

* Flatten nested let expressions. #140

* Use val instead of def when there are no arguments. #141

* Cosmetic improvement.

* Add type information to vals. #141

src/Morphir/Scala/AST.elm

@@ -111,6 +111,7 @@ type MemberDecl
     | ValueDecl
         { modifiers : List Mod
         , pattern : Pattern
+        , valueType : Maybe Type
         , value : Value
         }
     | FunctionDecl

src/Morphir/Scala/Backend.elm

@@ -477,6 +477,7 @@ mapValue value =
                                 Scala.ValueDecl
                                     { modifiers = []
                                     , pattern = Scala.NamedMatch (defName |> Name.toCamelCase)
+                                    , valueType = Just (mapType def.outputType)
                                     , value = mapValue def.body
                                     }
 
@@ -544,6 +545,7 @@ mapValue value =
                 [ Scala.ValueDecl
                     { modifiers = []
                     , pattern = mapPattern bindPattern
+                    , valueType = Nothing
                     , value = mapValue bindValue
                     }
                 ]

src/Morphir/Scala/PrettyPrinter.elm

@@ -121,6 +121,12 @@ mapMemberDecl opt memberDecl =
             concat
                 [ "val "
                 , mapPattern decl.pattern
+                , case decl.valueType of
+                    Just tpe ->
+                        concat [ ": ", mapType opt tpe ]
+
+                    Nothing ->
+                        empty
                 , " = "
                 , mapValue opt decl.value
                 ]
@@ -395,12 +401,20 @@ mapValue opt value =
                 [ "if "
                 , parens (mapValue opt condValue)
                 , " "
-                , statementBlock opt [ trueValue |> mapValue opt ]
+                , case trueValue of
+                    Block _ _ ->
+                        mapValue opt trueValue
+
+                    _ ->
+                        statementBlock opt [ mapValue opt trueValue ]
                 , " else "
                 , case falseValue of
                     IfElse _ _ _ ->
                         mapValue opt falseValue
 
+                    Block _ _ ->
+                        mapValue opt falseValue
+
                     _ ->
                         statementBlock opt [ mapValue opt falseValue ]
                 ]