`static[T]` parameter cannot depend on generic type parameter

[andreaferretti]

The following

type Modulo[A; M: static[A]] = distinct A

proc `$`[A; M: static[A]](x: Modulo[A, M]): string =
  $(A(x)) & " mod " & $(M)

proc modulo[A](a: A, M: static[A]): Modulo[A, M] = Modulo[A, M](a %% M)

proc `+`[A; M: static[A]](x, y: Modulo[A, M]): Modulo[A, M] =
  (A(x) + A(y)).modulo(M)

when isMainModule:
  echo (3.modulo(7) + 5.modulo(7))

does not compile, while I would expect it to print 1 mod 7. The error is

Error: cannot instantiate Modulo
got: <type A, M>
but expected: <A, M>

[andreaferretti]

Any chance this could be tagged v1? I have been wanting to use this for some cryptography work since #3706 (even the non generic version used to fail) and it would be really nice to know fixing this is on the roadmap.

[Araq]

I don't know how hard this is to support and I wouldn't want this to block v1. We have a lot on our plate already. Sorry.

[andreaferretti]

Fair enough :-)

[Araq]

I gave it another shot ... no progress so far...