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improve erasedValue section
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docs/docs/reference/metaprogramming/inline.md

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@@ -33,8 +33,8 @@ object Logger {
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The `Config` object contains a definition of the **inline value** `logging`.
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This means that `logging` is treated as a _constant value_, equivalent to its
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right-hand side `false`. The right-hand side of such an `inline val` must itself
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be a [constant expression](https://scala-lang.org/files/archive/spec/2.12/06-expressions.html#constant-expressions). Used in this
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way, `inline` is equivalent to Java and Scala 2's `final`. Note that `final`, meaning
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be a [constant expression](https://scala-lang.org/files/archive/spec/2.12/06-expressions.html#constant-expressions).
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Used in this way, `inline` is equivalent to Java and Scala 2's `final`. Note that `final`, meaning
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_inlined constant_, is still supported in Dotty, but will be phased out.
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The `Logger` object contains a definition of the **inline method** `log`. This
@@ -272,8 +272,8 @@ The scrutinee `x` is examined statically and the inline match is reduced
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accordingly returning the corresponding value (with the type specialized due to
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the `<:` in the return type). This example performs a simple type test over the
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scrutinee. The type can have a richer structure like the simple ADT below.
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`toInt` matches the structure of a number in Church-encoding and _computes_ the
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corresponding integer.
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`toInt` matches the structure of a number in [Church-encoding](https://en.wikipedia.org/wiki/Church_encoding)
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and _computes_ the corresponding integer.
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```scala
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trait Nat
@@ -319,11 +319,11 @@ the singleton type `2`.
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#### `erasedValue`
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We have seen so far inline methods that take terms (tuples and integers) as
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So far we have seen inline methods that take terms (tuples and integers) as
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parameters. What if we want to base case distinctions on types instead? For
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instance, one would like to be able to write a function `defaultValue`, that,
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given a type `T` returns optionally the default value of `T`, if it exists. In
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fact, we can already express this using rewrite match expressions and a simple
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given a type `T`, returns optionally the default value of `T`, if it exists.
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We can already express this using rewrite match expressions and a simple
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helper function, `scala.compiletime.erasedValue`, which is defined as follows:
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```scala
@@ -333,7 +333,7 @@ erased def erasedValue[T]: T = ???
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The `erasedValue` function _pretends_ to return a value of its type argument
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`T`. In fact, it would always raise a `NotImplementedError` exception when
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called. But the function can in fact never be called, since it is declared
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`erased`, so can be only used at compile-time during type checking.
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`erased`, so can only be used at compile-time during type checking.
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Using `erasedValue`, we can then define `defaultValue` as follows:
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@@ -360,10 +360,11 @@ Then:
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val dAny: None.type = defaultValue[Any]
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```
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As another example, consider the type-level version of `toNat` above the we call
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`toIntT`: given a _type_ representing a Peano number, return the integer _value_
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corresponding to it. Consider the definitions of numbers as in the _Inline
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Match_ section aboce. Here's how `toIntT` can be defined:
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As another example, consider the type-level version of `toInt` below:
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given a _type_ representing a [Peano number](https://wiki.haskell.org/Peano_numbers),
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return the integer _value_ corresponding to it.
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Consider the definitions of numbers as in the _Inline
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Match_ section above. Here is how `toIntT` can be defined:
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```scala
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inline def toIntT[N <: Nat] <: Int = inline scala.compiletime.erasedValue[N] match {

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