Fix example #35
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Fix example #35
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The rules for export forwarders are changed as follows. Previously, all export forwarders were declared `final`. Now, only term members are declared `final`. Type aliases left aside. This makes it possible to export the same type member into several traits and then mix these traits in the same class. `typeclass-aggregates.scala` shows why this is essential to be able to combine multiple givens with type members. The change does not lose safety since different type aliases would in any case lead to uninstantiatable classes.
Refinements of a class parent are added as synthetic members to the inheriting class. # Conflicts: # compiler/src/dotty/tools/dotc/config/ScalaSettings.scala # compiler/src/dotty/tools/dotc/typer/Implicits.scala # compiler/src/dotty/tools/dotc/typer/Namer.scala # tests/pos/typeclass-aggregates.scala
For a tracked class parameter we add a refinement in the constructor type that
the class member is the same as the parameter. E.g.
```scala
class C { type T }
class D(tracked val x: C) { type T = x.T }
```
This will generate the constructor type:
```scala
(x1: C): D { val x: x1.type }
```
Without `tracked` the refinement would not be added. This can solve several problems with dependent class
types where previously we lost track of type dependencies.
Make context bound evidence params tracked if they have types with abstract type members.
- Don't rely on ContextBoundParamName for desugaring - For the first context bound [X: B ...], use `X` as the name of the evidence parameter for `B`.
If a context bound type `T` for type parameter `A` does not have
type parameters, demand evidence of type `T { type This = A }` instead.
Allow the RHS of a type def to be higher-kinded. But keep the restriction for opaque type aliases; their RHS must be fully applied. I am not sure why the restriction applies to them, but there was a test specifically about that, so there night be a reason. # Conflicts: # compiler/src/dotty/tools/dotc/typer/Typer.scala
A type implemented in a given definition can now be an infix type, without enclosing parens being necessary. By contrast, it cannot anymore be a refined type. Refined types have to be enclosed in parens. This second point aligns the dotty parser with the published syntax and the scala meta parser.
given [A: Ord] => A is Ord:
...
given [A: Ord] => A is Ord as listOrd:
...
"This" suggests the meaning "the type of this", which is not the role of Self in type classes. Also Self is used in Swift and Rust, which have a similar typeclass design. # Conflicts: # compiler/src/dotty/tools/dotc/typer/Typer.scala # tests/pos/parsercombinators-arrow.scala
A definition like `given T = deferredSummon` in a trait will be expanded to an abstract given in the trait that is implemented automatically in all classes inheriting the trait.
Expand them to givens with deferred summons # Conflicts: # compiler/src/dotty/tools/dotc/ast/Desugar.scala
Make sure that any references to a synthetic evidence parameter come after that parameter is introduced.
Avoid accidental binding to self # Conflicts: # compiler/src/dotty/tools/dotc/typer/Typer.scala
The idea is that `given ... = deferred` should be the new syntax for abstract givens. These
can only be defined in traits and need to be implemented in the first subclass extending the
trait. If the definition of a given vals is missing, one is synthesized by an implicit search
at the site of the extending class.
This will free the syntax
given A is TC
for the more common case where we just want to implement a marker type class TC.
Also allow
# Conflicts:
# compiler/src/dotty/tools/dotc/typer/Namer.scala
To make an abstract given with new style syntax, one needs to write `= deferred`.
If a refined type has a parent type watching some other type, the parent should not be mapped to Object. Previously, the parent counted as `isEmpty` which caused this mapping. Also: Complete and cleanup hylolib tests
…5840 Faced with given C[T]: ... (with a new line after `:`) we now classify this as new given syntax, and assume ... is a template body. If one wants to use old syntax, one can still write given C[T] : ImplementedType ... # Conflicts: # compiler/src/dotty/tools/dotc/parsing/Parsers.scala
We already reduce `R { type A = T } # A` to `T` in most situations when we
create types. We now also reduce `R { val x: S } # x` to `S` if `S` is a
singleton type.
This will simplify types as we go to more term-dependent typing. As a concrete
benefit, it will avoid several test-pickling failures due to pickling differences
when using dependent types.
Exclude synthetic, unnamed context bound evidence parameters.
# Conflicts: # compiler/src/dotty/tools/dotc/typer/Typer.scala
Co-authored-by: Dale Wijnand <[email protected]>
Co-authored-by: Dale Wijnand <[email protected]>
|
Hello @odersky , is this how the example is intended to work? |
odersky
requested changes
Jan 14, 2024
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