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everson/CoolStuff.scala

Last active August 29, 2015 14:13
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scalaz.Tag
Raw
CoolStuff.scala
import scalaz._
import Scalaz._
val isThisCool: Boolean @@ CoolStuff = Tag(true)
def requiresCoolStuff(in: Boolean @@ CoolStuff) = in
// type checks
requiresCoolStuff(isThisCool)
if(isThisCool) "still act as bool" else "oops"
/*
<console>:22: error: type mismatch;
found : Boolean(true)
required: scalaz.@@[Boolean,CoolStuff]
(which expands to) Boolean with AnyRef{type Tag = CoolStuff}
requiresCoolStuff(true)
*/
requiresCoolStuff(true)
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