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Mar 24, 2018
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new line after rule heading #4174

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1912e08
new line after rule heading
robstoll Mar 24, 2018
f87507a
Fix indentation
allanrenucci Mar 24, 2018
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53 changes: 30 additions & 23 deletions docs/docs/reference/erased-terms.md
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Expand Up @@ -147,10 +147,10 @@ object Test {
Rules
-----

1) The `erased` modifier can appear:
* At the start of a parameter block of a method, function or class
* In a method definition
* In a `val` definition (but not `lazy val` or `var`)
1. The `erased` modifier can appear:
* At the start of a parameter block of a method, function or class
* In a method definition
* In a `val` definition (but not `lazy val` or `var`)

```scala
erased val x = ...
Expand All @@ -164,33 +164,40 @@ def h(x: erased Int => Int) = ...
class K(erased x: Int) { ... }
```

2) A reference to an `erased` definition can only be used
* Inside the expression of argument to an `erased` parameter
* Inside the body of an `erased` `val` or `def`

3) Functions
* `(erased x1: T1, x2: T2, ..., xN: TN) => y : (erased T1, T2, ..., TN) => R`
* `(implicit erased x1: T1, x2: T2, ..., xN: TN) => y : (implicit erased T1, T2, ..., TN) => R`
* `implicit erased T1 => R <:< erased T1 => R`
* `(implicit erased T1, T2) => R <:< (erased T1, T2) => R`
* ...
2. A reference to an `erased` definition can only be used
* Inside the expression of argument to an `erased` parameter
* Inside the body of an `erased` `val` or `def`


3. Functions
* `(erased x1: T1, x2: T2, ..., xN: TN) => y : (erased T1, T2, ..., TN) => R`
* `(implicit erased x1: T1, x2: T2, ..., xN: TN) => y : (implicit erased T1, T2, ..., TN) => R`
* `implicit erased T1 => R <:< erased T1 => R`
* `(implicit erased T1, T2) => R <:< (erased T1, T2) => R`
* ...

Note that there is no subtype relation between `erased T => R` and `T => R` (or `implicit erased T => R` and `implicit T => R`)

4) Eta expansion

4. Eta expansion

if `def f(erased x: T): U` then `f: (erased T) => U`.


5) Erasure Semantics
* All `erased` paramters are removed from the function
* All argument to `erased` paramters are not passed to the function
* All `erased` definitions are removed
* All `(erased T1, T2, ..., TN) => R` and `(implicit erased T1, T2, ..., TN) => R` become `() => R`
5. Erasure Semantics
* All `erased` paramters are removed from the function
* All argument to `erased` paramters are not passed to the function
* All `erased` definitions are removed
* All `(erased T1, T2, ..., TN) => R` and `(implicit erased T1, T2, ..., TN) => R` become `() => R`


6. Overloading

6) Overloading
Method with `erased` parameters will follow the normal overloading constraints after erasure.

7) Overriding
* Member definitions overidding each other must both be `erased` or not be `erased`
* `def foo(x: T): U` cannot be overriden by `def foo(erased x: T): U` an viceversa

7. Overriding
* Member definitions overidding each other must both be `erased` or not be `erased`
* `def foo(x: T): U` cannot be overriden by `def foo(erased x: T): U` an viceversa