Document the boxed classes of primitive types. #491
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doc/semantics.md
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| ### `getClass()` for values of primitive types | |||
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You'll have to update the introductory text that says "three exceptions".
Also, if you touch that, it'd be nice to link to a definition of what primitive types are (I assume it's JVM primitive types? or is it IR primitive types? or is it Scala primitive types (is there such a thing))?
doc/semantics.md
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| ### `getClass()` for values of primitive types | |||
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having "primitive types" in the title seems redundant. The entire section is about primitive data types.
| Moreover, for `()` (unit), the result will be `classOf[java.lang.Void]` instead of `classOf[scala.runtime.BoxedUnit]` like the JVM. | ||
| `scala.runtime.BoxedUnit` is an implementation detail of Scala on the JVM, which Scala.js does not emulate. | ||
| Instead, it uses the more sensible `java.lang.Void`, as `Void` is the boxed class corresponding to the `void` primitive type, which is `scala.Unit`. | ||
| This also manifests itself in `Array[Unit]` which is effectively `Array[java.lang.Void]` at run-time, instead of `Array[scala.runtime.BoxedUnit]`. |
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It might be helpful to add a sentence explaining that on the JVM, jl.Void is uninstantiable and Scala.js has made the choice to violate this part of the JDK spec in favor of not needing sr.BoxedUnit.
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I added
This means that while
java.lang.Voidis not instantiable on the JVM, in Scala.js it has a singleton instance, namely().
Does that correspond to what you were asking?
sjrd
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Updated. |
| Moreover, for `()` (unit), the result will be `classOf[java.lang.Void]` instead of `classOf[scala.runtime.BoxedUnit]` like the JVM. | ||
| `scala.runtime.BoxedUnit` is an implementation detail of Scala on the JVM, which Scala.js does not emulate. | ||
| Instead, it uses the more sensible `java.lang.Void`, as `Void` is the boxed class corresponding to the `void` primitive type, which is `scala.Unit`. | ||
| This also manifests itself in `Array[Unit]` which is effectively `Array[java.lang.Void]` at run-time, instead of `Array[scala.runtime.BoxedUnit]`. |
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