Clarify documentation for Nothing class #5582
Open
+2
−2
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Add specification about "ill-defined" or "undefined" value in the semantic of the formal language (Kotlin)
fzhinkin
requested changes
Dec 5, 2025
| * Nothing has no instances. You can use Nothing to represent "a value that never exists": for example, | ||
| * if a function has the return type of Nothing, it means that it never returns (always throws an exception). | ||
| * Nothing has no instances. You can use Nothing to represent semantically an "undefined value" or "a value that never exists": for example, | ||
| * if a function has the return type of Nothing, it means that it never returns a value accept by the Kotlin (always throws an exception). |
Contributor
There was a problem hiding this comment.
That's incorrect: such functions are indeed never return normally (in control-flow sense).
| /** | ||
| * Nothing has no instances. You can use Nothing to represent "a value that never exists": for example, | ||
| * if a function has the return type of Nothing, it means that it never returns (always throws an exception). | ||
| * Nothing has no instances. You can use Nothing to represent semantically an "undefined value" or "a value that never exists": for example, |
Contributor
There was a problem hiding this comment.
Could you please provide an example of how Nothing could be used to represent an undefined value?
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Add specification about ill-defined or undefined value in the semantic of the formal language (Kotlin)