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Handle type parameters when computing lowest common supertype #860

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lars-reimann opened this issue Feb 6, 2024 · 1 comment · Fixed by #901
Closed

Handle type parameters when computing lowest common supertype #860

lars-reimann opened this issue Feb 6, 2024 · 1 comment · Fixed by #901
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lars-reimann commented Feb 6, 2024 •
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lowestCommonSupertype must be updated to handle:

  • class types with type parameters,
  • type parameter types,

Ideas for implementation:

  • When computing lowest common super type, replace type parameters by their upper bound.
  • When computing highest common subtype, replace type parameters by their lower bound.
  • This also needs a new method highestCommonSubtype to handle contravariant type parameters.
@lars-reimann lars-reimann mentioned this issue Feb 6, 2024
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@lars-reimann lars-reimann added this to DSL Feb 6, 2024
@github-project-automation github-project-automation bot moved this to Backlog in DSL Feb 6, 2024
@lars-reimann lars-reimann changed the title lowestCommonSupertypeForClassBasedTypes must take type parameters into account (+variance) Handle type parameters when computing lowest common supertype Feb 6, 2024
@lars-reimann lars-reimann self-assigned this Feb 6, 2024
@lars-reimann lars-reimann moved this from Backlog to Todo in DSL Feb 6, 2024
@lars-reimann lars-reimann added this to the v0.7.0 milestone Feb 6, 2024
@lars-reimann lars-reimann moved this from Todo to In Progress in DSL Feb 7, 2024
@lars-reimann lars-reimann mentioned this issue Feb 8, 2024
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@lars-reimann lars-reimann linked a pull request Feb 8, 2024 that will close this issue
feat: handle invariant/covariant type parameters when computing lowest common supertype #868
Merged
@lars-reimann lars-reimann modified the milestones: v0.7.0, v0.8.0 Feb 10, 2024
@lars-reimann lars-reimann moved this from In Progress to Backlog in DSL Feb 10, 2024
@lars-reimann lars-reimann moved this from Backlog to Todo in DSL Feb 12, 2024
@lars-reimann lars-reimann moved this from Todo to In Progress in DSL Feb 12, 2024
@lars-reimann lars-reimann removed a link to a pull request Feb 18, 2024
feat: handle invariant/covariant type parameters when computing lowest common supertype #868
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lars-reimann added a commit that referenced this issue Feb 18, 2024
@lars-reimann
feat: handle invariant/covariant type parameters when computing lowes…
4d6cb4e 
…t common supertype (#868)

Closes partially #860

### Summary of Changes

Invariant/covariant type parameters are now handled when computing the
lowest common supertype of a list of types. This functionality is used
to compute the type of
* lists (based on their elements)
* maps (based on their keys and values)
* elvis operator (based on their operands).

It's also needed later for #861. Contravariant type parameters need a
means to compute the highest common subtype, which will be tackled in a
future PR.
@lars-reimann lars-reimann mentioned this issue Feb 19, 2024
Merged
lars-reimann added a commit that referenced this issue Feb 19, 2024
@lars-reimann
feat: improvements to constraints (#896)
b81bef9 
Closes partially #18

### Summary of Changes

* Remove lower type parameter bounds. We don't have a use case for them
and they vastly complicated the implementation. For instance, `Nothing`
is no subtype of a type parameter type with a lower bound other than
`Nothing`. This means, when computing the highest common subtype (#860),
we could only return `$unknown` for a type parameter type with a lower
bound of, say, `Int`, and another type like `Number`.
* Specify the upper bound of a type parameter directly where it's
declared. Since they cannot also have a lower bound anymore and
previously could only have a single, acyclic upper bound, we don't lose
additional expressiveness this way. Previous type parameters may be used
as the upper bound of later ones. The scope provider prevents forward
references.
* Add syntax, formatting and scoping for parameter bounds (#18). We are
doing this in this PR, since we would otherwise not have constraints to
test constraint lists with.
@lars-reimann lars-reimann mentioned this issue Feb 20, 2024
Merged
lars-reimann added a commit that referenced this issue Feb 20, 2024
@lars-reimann
feat: compute highest common subtype (#901)
5630a9f 
Closes #860

### Summary of Changes

Add a function to compute the highest common subtype of a list of types.
This is needed to compute the lowest common supertype of a list of types
with contravariant type parameters. Example:

```
class Consumer<in T>
class Logger sub Consumer<String>

segment mySegment(
    p1: Consumer<Any>,
    p2: Logger,
) {
    val a = [p1, p2];
}
```

We can now infer the type of the placeholder `a` to
`List<Consumer<String>>`, where previously we would have inferred
`List<Consumer<Nothing>>`.
@github-project-automation github-project-automation bot moved this from In Progress to ✔️ Done in DSL Feb 20, 2024
lars-reimann pushed a commit that referenced this issue Feb 26, 2024
@semantic-release-bot
chore(release): 0.8.0 [skip ci]
c22ab5f 
## [0.8.0](v0.7.0...v0.8.0) (2024-02-26)

### Features

* check the runner version to be compatible ([#888](#888)) ([83378a3](83378a3)), closes [#880](#880)
* check type parameter bounds for default values and named types ([#919](#919)) ([7003ea6](7003ea6)), closes [#614](#614)
* clamp default values of parameter types to upper bound ([#921](#921)) ([76ad869](76ad869))
* compute highest common subtype ([#901](#901)) ([5630a9f](5630a9f)), closes [#860](#860)
* compute type parameters for calls ([#920](#920)) ([35dc826](35dc826)), closes [#861](#861)
* consider nullability of upper type parameter bound in various checks ([#892](#892)) ([940515a](940515a))
* constraints for segments ([#911](#911)) ([e57f886](e57f886)), closes [#903](#903)
* EDA on pipeline Tables ([#834](#834)) ([f42c9aa](f42c9aa))
* error if parent type is nullable ([#891](#891)) ([add650d](add650d))
* escape characters in string conversion of string constants ([#908](#908)) ([72a9c3c](72a9c3c)), closes [#904](#904)
* format upper bound of type parameters ([#898](#898)) ([9d6ce28](9d6ce28))
* handle invariant/covariant type parameters when computing lowest common supertype ([#868](#868)) ([4d6cb4e](4d6cb4e)), closes [#860](#860) [#861](#861)
* improve handling of subclasses of lists/maps ([#890](#890)) ([bb0c94b](bb0c94b))
* improvements to constraints ([#896](#896)) ([b81bef9](b81bef9)), closes [#18](#18) [#860](#860) [#18](#18)
* include enum name in string conversion of enum variant types ([#907](#907)) ([1f6502e](1f6502e)), closes [#902](#902)
* scoping for member accesses if receiver has type parameter type ([#889](#889)) ([1277bd1](1277bd1))
* shorter message if runner is started but files have errors ([#912](#912)) ([b611b44](b611b44)), closes [#910](#910)
* simplify union types containing type parameter types disregarding entry order ([#894](#894)) ([cf6e77e](cf6e77e))
* singular type is its own lowest common supertype ([#893](#893)) ([79d611d](79d611d))
* substitute type parameter when type checking calls ([#923](#923)) ([2e09306](2e09306)), closes [#915](#915)
* substitute type parameters when checking overridden members ([#922](#922)) ([0e657cf](0e657cf)), closes [#917](#917)
* update to `safe-ds-runner` v0.7.0 ([#906](#906)) ([070f406](070f406))
* use bounds of type system where possible ([#899](#899)) ([cf92762](cf92762))

### Bug Fixes

* lenient type checking involving type parameter types ([#916](#916)) ([b9d3641](b9d3641)), closes [#915](#915) [#915](#915)
* runner startup silent failure ([#914](#914)) ([8812944](8812944)), closes [#909](#909)
* save dirty files before running pipeline ([#918](#918)) ([4302ca6](4302ca6))
* simplification of union types ([#897](#897)) ([4c577a3](4c577a3))
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🎉 This issue has been resolved in version 0.8.0 🎉

The release is available on:

Your semantic-release bot 📦🚀

@lars-reimann lars-reimann added the released Included in a release label Feb 26, 2024
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feat: compute highest common subtype Safe-DS/DSL
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