Allow all annotations to take full expressions #1230
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(Sorry)
Instead of just application expressions, since some annotations
were allowed to take full expressions, it makes sense to allow
them all to do so.
Otherwise there are weird corner cases like
merge { x = λ(y : Bool) → y } < x >.x : (∀(y : Bool) → Bool)
parses as a merge-with-annotation while
merge { x = λ(y : Bool) → y } < x >.x : ∀(y : Bool) → Bool
parses as a merge-without-annotation plus annotation, just like
(merge { x = λ(y : Bool) → y } < x >.x) : ∀(y : Bool) → Bool
Now the first two will parse the same.
Gabriella439
approved these changes
Oct 1, 2021
|
Sorry, I totally forgot to merge this! 😅 Thank you for doing this |
Gabriella439
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Oct 21, 2021
… as standardized in dhall-lang/dhall-lang#1230
Gabriella439
added a commit
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Oct 23, 2021
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Instead of just application expressions, since some annotations were allowed to take full expressions, it makes sense to allow them all to do so.
Otherwise there are weird corner cases like
merge { x = λ(y : Bool) → y } < x >.x : (∀(y : Bool) → Bool)parses as a merge-with-annotation while
merge { x = λ(y : Bool) → y } < x >.x : ∀(y : Bool) → Boolparses as a merge-without-annotation plus annotation, just like
(merge { x = λ(y : Bool) → y } < x >.x) : ∀(y : Bool) → Bool(from https://github.com/dhall-lang/dhall-lang/blob/1907a1d1a6dff9ff8638547f7bc49d6b5135bcdf/tests/type-inference/success/unit/MergeOneWithAnnotation1A.dhall)
Now the second will parse like the first, instead of like the last.
Of course we should discuss whether this is a breaking change, but I think the actual user-facing effects will be minimal, since the difference in annotations are normalized away.
This came up in fixing my pretty printer – I don't think there's a good way for me to disambiguate the old way correctly within my current system of precedence.
I also removed trailing spaces in a separate commit and noticed that the file uses CRLF line endings which is very weird. Happy to revert that commit if you want …