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From TypeTag to =:= #11215

durban opened this Issue Oct 19, 2018 · 0 comments


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durban commented Oct 19, 2018

Unless I'm missing something, there is no safe way (i.e., without using an asInstanceOf) to go from two TypeTags with equal types (as computed by tag.tpe.=:=) to an instance of =:=. Is this actually unsafe? If not, would it make sense to have a way to do this in the standard library?

For reference, the unsafe way to write this is:

def fromTags[A, B](A: TypeTag[A], B: TypeTag[B]): Option[A =:= B] = {
  if (A.tpe =:= B.tpe) Some(=:=.tpEquals[A].asInstanceOf[A =:= B])
  else None

@hrhino hrhino added this to the Backlog milestone Oct 19, 2018

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