[Solved] Scala 3 macro: how to express the method that uses Type[_] implicit as a polymorphic function?

Question
1

How can I define newValF shown below? I keep getting errors in the using parameter.

TIA

    def newVal[S: Type](cls: Symbol, name: String, t : Expr[S]) = 
      // Later we map to columns T
      println(s"$name : ${TypeRepr.of[S].show} = ?")
      Symbol.newVal(cls, name, TypeRepr.of[S], Flags.EmptyFlags /*Flags.Inline*/, Symbol.noSymbol )

    val newValF = 
         [A, S] => (cls: Symbol, name: String, t : Expr[S]) => (using Type[S]) => newVal[S](cls, name, t)
2

Maybe using context functions? Context Functions

2 Likes
3

@WojciechMazur Thanks. It worked (for version 3.4.2). For future reference here is a code snippet:

    def newVal[S: Type](cls: Symbol, name: String, t : Expr[S]) = 
      println(s"$name : ${TypeRepr.of[S].show} = ?")
      Symbol.newVal(cls, name, TypeRepr.of[S], Flags.EmptyFlags, Symbol.noSymbol )

    def newValF[S] : [S] => (Symbol, String, Expr[S]) => Type[S] ?=> Symbol =
        [S] => (a: Symbol, b: String, c: Expr[S]) => newVal[S](a,b,c)

    def valList2[A](cls: Symbol, x: Expr[IMap], map: [S] => (Symbol, String, Expr[S]) => Type[S] ?=> A ): List[A] =
   ...
            val value = map(cls, name, valueValue)
   ...

To make it easier to read, one can also use a type alias.

1 Like