Strange Macro Behavior

[schmidh]

Following code runs into problems when using different types of Generators. A 
Generator is just a proc with no parameters that returns some type of value.

[https://play.nim-lang.org/#ix=2cRz](https://play.nim-lang.org/#ix=2cRz)
    
    
    import macros, sugar
    
    type Generator[T] = () -> T
    
    proc gen1(): float =
      result = 42.0
    
    proc gen2(): int =
      result = 66
    
    proc gen3(): string =
      result = "Hello"
    
    macro genTuple1[T](gen1: Generator[T]): untyped =
      result = newStmtList()
    
    macro genTuple2[T, U](gen1: Generator[T], gen2: Generator[U]): untyped =
      result = newStmtList()
    
    macro genTuple3[T, U, V](gen1: Generator[T], gen2: Generator[U], gen3: 
Generator[V]): untyped =
      result = newStmtList()
    
    # ... and so on and so forth
    
    # Would love to have s.th like that but obviously not valid syntax
    macro genTuple(args: varargs[Generator[auto]]): untyped =
      result = newStmtList()
    
    genTuple1(gen1) # works
    genTuple2(gen1, gen2)
    #[
    Error: type mismatch: got <proc (): float{.noSideEffect, gcsafe, locks: 
0.}, proc (): int{.noSideEffect, gcsafe, locks: 0.}>
    but expected one of:
    macro genTuple2[T, U](gen1: Generator[T]; gen2: Generator[U]): untyped
      first type mismatch at position: 2
      required type for gen2: Generator[genTuple2.U]
      but expression 'gen2' is of type: proc (): int{.noSideEffect, gcsafe, 
locks: 0.}
    ]#
    
    # When all Generators are of the same type, e.g. Generator[int] then no 
problem
    genTuple2(gen2, gen2)
    
    # same type mismatch error message
    genTuple3(gen1, gen2, gen3)
    
    
    Run

I'm doing something wrong here. But don't know really what. Maybe generics are 
not really allowed with macros?