Type Lambdas Spec #5217
Type Lambdas Spec #5217
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Some things that could be expanded on:
- Equivalence between
type Foo[A] = Bandtype Foo = [A] => B - Equivalence between
def foo[M[X] <: B]anddef foo[M <: [X] => B] - Currying (
type Foo[A] = [X] => A,type Foo = [A] => [X] => A)- Especially the interaction with type inference which currently doesn't really work (e.g. should we do anything sensible with
def foo[T, S, M <: [A] => [B] => (A, B)](x: M[T, S])?)
- Especially the interaction with type inference which currently doesn't really work (e.g. should we do anything sensible with
- variance rules for the bounds of the type parameters of the lambda.
| ``` | ||
| and two types `S <: T`, we have | ||
| ``` | ||
| TL1[S] <: TL1[T |
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Any comments? If not let's get this in. We have lots of other parts to work on as well. |
| ```scala | ||
| type T >: ([X] => L) <: ([X] => U) | ||
| ``` | ||
| However, if `L` is `Nothing` it is not parameterized, since `Nothing` is treated as a bottom type for all kinds. For instance, |
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Is this exception necessary, or is it an optimization?
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It's a design choice. Whether it's necessary or not can be determined only by trying to change it and observing what breaks 😉
| ``` | ||
| where `v1` and `v2` are optional variance annotations: `+`, `-`, or absent. | ||
| Then `TL1 <: TL2`, if the type interval `L2..U2` is contained in the type interval `L1..U1` (i.e. | ||
| `L1 <: L2` and `U2 <: U1`), and either `v2` is absent or `v1 = v2`. |
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The subtyping rule says nothing about R1 and R2. That looks suspicious to me. Shouldn't R1 <: R2?
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I second @smarter's comment. |
| --- | ||
| layout: doc-page | ||
| title: "Type Lambdas - More Details" | ||
| --- |
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This document should be added to docs/sidebar.yml.
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@nicolasstucki No, spec pages should not be part of sidebar.yml. They should be referred to from the main page of the topic. |
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