FazBrowse GitHub Viewer | Trending |
URL:
| Home
Tools: [Download Repo ZIP]   [Original HTTPS Page]

Normalize union/intersection type combinations by ahejlsberg · Pull Request #11717 · microsoft/TypeScript · GitHub

/ TypeScript Public

Normalize union/intersection type combinations - #11717

Merged
Anders Hejlsberg (ahejlsberg) merged 4 commits into
masterfrom
normalizeIntersectionTypes
Oct 19, 2016
ConversationCommits (4)ChecksFiles changed
Merged

Normalize union/intersection type combinations#11717
Anders Hejlsberg (ahejlsberg) merged 4 commits into
masterfrom
normalizeIntersectionTypes

Conversation

Anders Hejlsberg (ahejlsberg) commented Oct 18, 2016 •
edited
Loading

Copy link
Copy Markdown
Member

With this PR we normalize combinations of intersection and union types based on the distributive property of the & type operator over the | type operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection types with union type constituents into equivalent union types with intersection type constituents and thus ensure that union types are always at the top level in type representations and equivalent ways of writing the same type are treated identically.

interface A { a: string }
interface B { b: string }
interface C { c: string }
interface D { d: string }

// Identical ways of writing the same type
type X1 = (A | B) & (C | D);
type X2 = A & (C | D) | B & (C | D);
type X3 = A & C | A & D | B & C | B & D;

In the example above, X1, X2, and X3 are all identical types that reference the normalized form A & C | A & D | B & C | B & D.

Fixes #9919.

Anders Hejlsberg (ahejlsberg) mentioned this pull request Oct 18, 2016
Closed
Nathan Shively-Sanders (sandersn) requested changes Oct 18, 2016
View reviewed changes

Nathan Shively-Sanders (sandersn) left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

One question about isRelatedTo and a possible improvement for reporting errors with intersections of boolean.

Comment thread tests/baselines/reference/errorMessagesIntersectionTypes04.errors.txt
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(18,5): error TS2322: Type 'A & B' is not assignable to type 'boolean'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(19,5): error TS2322: Type 'A & B' is not assignable to type 'string'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(21,5): error TS2322: Type 'number & boolean' is not assignable to type 'string'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(21,5): error TS2322: Type '(number & true) | (number & false)' is not assignable to type 'string'.

Nathan Shively-Sanders (sandersn) Oct 18, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

Is there some way to present this error as number & boolean still? I feel like the distributed form is unexpected here.

Anders Hejlsberg (ahejlsberg) Oct 18, 2016

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

The actual representation needs to be (number & true) | (number & false), but we could play tricks in the type-to-string logic to turn it into number & boolean. Not sure it's worth it though as those types are all rather meaningless anyway.

Nathan Shively-Sanders (sandersn) Oct 19, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

Yeah, type-to-string is what I was thinking of. But you're right, & boolean probably only shows up in our tests.

Comment thread src/compiler/checker.ts
return result;
}
}
else if (source.flags & TypeFlags.Intersection) {

Nathan Shively-Sanders (sandersn) Oct 18, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

why not check the source first here too? I think that's the normal pattern for isRelatedTo

Anders Hejlsberg (ahejlsberg) Oct 18, 2016

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

The comment above the initial if statement explains why. For intersection types, the target side is an "each" relationship and the source side is a "some" relationship. We need to deconstruct "each" relationships first to get the correct results.

Nathan Shively-Sanders (sandersn) Oct 19, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

OK, so I think I misunderstood the parts of the code that are independent post-distribution. It would work to put intersections before unions now, where it wouldn't before, right?

Marin Marinov (gcnew) mentioned this pull request Oct 19, 2016
Closed
Nathan Shively-Sanders (sandersn) approved these changes Oct 19, 2016
View reviewed changes
Comment thread src/compiler/checker.ts
return result;
}
}
else if (source.flags & TypeFlags.Intersection) {

Nathan Shively-Sanders (sandersn) Oct 19, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

OK, so I think I misunderstood the parts of the code that are independent post-distribution. It would work to put intersections before unions now, where it wouldn't before, right?

Comment thread tests/baselines/reference/errorMessagesIntersectionTypes04.errors.txt
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(18,5): error TS2322: Type 'A & B' is not assignable to type 'boolean'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(19,5): error TS2322: Type 'A & B' is not assignable to type 'string'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(21,5): error TS2322: Type 'number & boolean' is not assignable to type 'string'.
tests/cases/compiler/errorMessagesIntersectionTypes04.ts(21,5): error TS2322: Type '(number & true) | (number & false)' is not assignable to type 'string'.

Nathan Shively-Sanders (sandersn) Oct 19, 2016

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Choose a reason Spam Abuse Off Topic Outdated Duplicate Resolved Low Quality

Yeah, type-to-string is what I was thinking of. But you're right, & boolean probably only shows up in our tests.

Anders Hejlsberg (ahejlsberg) deleted the normalizeIntersectionTypes branch October 19, 2016 20:15
Troy Gerwien (yortus) mentioned this pull request Oct 21, 2016
Closed
Anders Hejlsberg (ahejlsberg) mentioned this pull request Nov 2, 2016
Closed
Closed
Ethan Resnick (ethanresnick) mentioned this pull request Nov 16, 2016
Closed
Closed
Mohamed Hegazy (mhegazy) mentioned this pull request Nov 18, 2016
Closed
Anders Hejlsberg (ahejlsberg) mentioned this pull request Nov 28, 2016
Closed
Anders Hejlsberg (ahejlsberg) mentioned this pull request May 17, 2017
Closed
Anders Hejlsberg (ahejlsberg) mentioned this pull request Sep 13, 2017
Merged
Microsoft (microsoft) locked and limited conversation to collaborators Jun 19, 2018
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
Show hidden characters
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.

Reviewers

Nathan Shively-Sanders (sandersn) sandersn approved these changes
+1 more reviewer
Mohamed Hegazy (mhegazy) mhegazy approved these changes
Reviewers whose approvals may not affect merge requirements

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

4 participants

Back | FazBrowse Home | New Git URL