If you run this in scala with the -Xlog-implicits argument passed, you get more information: scala.this.Prefed.conforms is not a valid implicit value for (T) => Ordered[T] because: type mismatch: found : <:<[T,T] required: (T) => Ordered[T] scala.this.predef.conforms is not a valid implicit value for (Ordered[T]) => Ordered[Ordered[T]] because: type mismatch: found : <:<[Ordered[T], Ordered[T]] required … Read more
This works as written as of the most recent shapeless 2.1.0-SNAPSHOT.
Scala has a restriction on automatic conversions to add a method, which is that it won’t apply more than one conversion in trying to find methods. For example: class A(val n: Int) class B(val m: Int, val n: Int) class C(val m: Int, val n: Int, val o: Int) { def total = m + … Read more
implicitly is avaliable in Scala 2.8 and is defined in Predef as: def implicitly[T](implicit e: T): T = e It is commonly used to check if an implicit value of type T is available and return it if such is the case. Simple example from retronym’s presentation: scala> implicit val a = “test” // define … Read more
I thought this was asked already, but, if so, the question isn’t apparent in the “related” bar. So, here it is: What is a View Bound? A view bound was a mechanism introduced in Scala to enable the use of some type A as if it were some type B. The typical syntax is this: … Read more
Types of Implicits Implicits in Scala refers to either a value that can be passed “automatically”, so to speak, or a conversion from one type to another that is made automatically. Implicit Conversion Speaking very briefly about the latter type, if one calls a method m on an object o of a class C, and … Read more