promoting to Number on integer x number operation about spire HOT 11 CLOSED

I think those implicits will probably need to be opt-in, since many users may not want this behavior by default. But it's a good point. We can certainly give Number implicits to go from all the other number types to Number.

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Hi Erik and others. Hope you don't mind me throwing my 2 cents in. I'm attempting to build a parametric geometry modeler using spire, because one nice feature would the ability to use doubles, complex numbers, or even hyper dual numbers. Therefore, I am writing all my methods using the spire version of Numeric. I have noticed I have to always use the fromDouble() method to work with literal doubles, however. Are there some implicits I'm failing to import? Would be nice to not have to write:

val y = x * fromDouble(2.0) // wish it could be x * 2.0 and get y:Numeric[Double]

fyi, x is a Numeric[Double]

just my thoughts and yes I am new to Scala and spire...but learning fast. thanks for your contributions. hope I can help in some way someday soon.

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Hm. I guess the best way to accomplish all of this would be to have some optional packages that can be imported to achieve this. These behaviors are probably not great to have on all-the-time although I totally see why they would be useful.

I'm still working on some of the other changes to Number. I'll try to push those tonight so you all can give some feedback.

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This should be working in the 2.10.0 branch. (For Number). No extra imports should be required besides spire.math._.

dlrodriguez, can you open a new ticket for your issue? I will look into it but I'm going to close this one since it is working for me now.

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It seems to work only in one direction:

scala> Number(1) + SafeLong(7)
res5: spire.math.Number = IntNumber(8)

scala> SafeLong(7) + Number(1)
:48: error: could not find implicit value for evidence parameter of type spire.algebra.AdditiveMonoid[scala.math.ScalaNumericConversions with scala.math.Ordered[_ >: spire.math.SafeLong with spire.math.Number <: scala.math.ScalaNumericConversions with scala.math.Ordered[_ >: spire.math.SafeLong with spire.math.Number <: scala.math.ScalaNumericConversions]]]
SafeLong(7) + Number(1)

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Hm, I thought I tested that. Time to work on it some more...

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This should be fixed again.

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But it gets the wrong type, when the safelong is left:

scala> Number(1) + SafeLong(7)
res12: spire.math.Number = IntNumber(8)

scala> SafeLong(7) + Number(1)
res9: spire.math.Number = FloatNumber(8.0)

On 01/06/2013 01:47 AM, Erik Osheim wrote:

This should be fixed again.

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#45 (comment).

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Yeah, that is going to be a little more difficult to fix. All I can say is that implicit conversions are annoying and it's really easy to hit ambiguities. Right now we're just converting to Double in that position so that all conversions pass through the same implicit and we avoid ambiguity.

I don't love it either, but I can't promise it will be fixed soon. Given that Scala has special built-in support for numeric coercisions (which only works for the built-in types) I can't promise that all of Spire's types are going to magically coerce quite as well as we'd like.

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Actually nevermind there probably is an easier way to fix this.

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This should be improved now. Thanks for your feedback!

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