Ring.mapRing => diverging chain of implicits. about algebird HOT 5 CLOSED

What type are you trying to resolve? We haven't seen that internally (and Flavian has been doing some matrices of Maps actually).

We are limited somewhat by the compiler, but generally we have been able to work around it. Please post the full compiler error.

from algebird.

Without seeing the code, I suspect the solution here is to have the templated function in question take an implicit Ring parameter - so you have
def myFn[T:Ring](...)
instead of just
def myFn[T](...)

That way the implicit gets resolved at the callsite where the concrete type of T is known, vs. in the templated function. (Of course this may need to happen for any number of levels up the call chain until you get to the point where T is not generic... implicits "infect" code very similarly to checked exceptions).

from algebird.

Sorry for my reticence. I'll try this. The thing in question was basically like:

trait SomeMatrixOps[T, ValT] {
  def foo(p : Pipe, q : Pipe) = {
    val m1 = p.toMatrix[T,T,ValT](...)
    val m2 = q.toMatrix[T,T,ValT](...)
    m1 * m2
  }
}

from algebird.

Avi is right. I think you need:

trait SomeMatrixOps[T, ValT] {
  implicit def ring: Ring[ValT]
  def foo(p : Pipe, q : Pipe) = {
    val m1 = p.toMatrix[T,T,ValT](...)
    val m2 = q.toMatrix[T,T,ValT](...)
    m1 * m2
  }
}

And then when you implement:

class MyMatrixOps[T,ValT:Ring] {
  override def ring = implicitly[Ring[ValT]]
}

I think that works.

from algebird.

Great thanks. I'm still trying to figure out what the compiler actually does when you get generics and implicits together like this...

from algebird.