René's URL Explorer Experiment


Title: Further improve match statement narrowing against unions by hauntsaninja · Pull Request #20744 · python/mypy · GitHub

Open Graph Title: Further improve match statement narrowing against unions by hauntsaninja · Pull Request #20744 · python/mypy

X Title: Further improve match statement narrowing against unions by hauntsaninja · Pull Request #20744 · python/mypy

Description: Optional static typing for Python. Contribute to python/mypy development by creating an account on GitHub.

Open Graph Description: I realised there is a simpler and more complete approach than the one taken in #19600. This adds the new "Step 2" to the original code. Best way to review the diff is probably to check it...

X Description: I realised there is a simpler and more complete approach than the one taken in #19600. This adds the new "Step 2" to the original code. Best way to review the diff is probably to ...

Opengraph URL: https://github.com/python/mypy/pull/20744

X: @github

direct link

Domain: github.com

route-pattern/_view_fragments/voltron/pull_requests/show/:user_id/:repository/:id/pull_request_layout(.:format)
route-controllervoltron_pull_requests_fragments
route-actionpull_request_layout
fetch-noncev2:173f7ef2-bb30-4689-b8bb-b55f6d0172c9
current-catalog-service-hashae870bc5e265a340912cde392f23dad3671a0a881730ffdadd82f2f57d81641b
request-idC7D0:28017F:505894:6AA099:6A58029C
html-safe-noncef0ad21b0c372e1e1fbb4e4a7e9a8e051b3f026fdf279b8e9aa51c84f63e1ec92
visitor-payloadeyJyZWZlcnJlciI6IiIsInJlcXVlc3RfaWQiOiJDN0QwOjI4MDE3Rjo1MDU4OTQ6NkFBMDk5OjZBNTgwMjlDIiwidmlzaXRvcl9pZCI6IjkwMzk0NTk4ODk3NTY3NjY4NzYiLCJyZWdpb25fZWRnZSI6ImlhZCIsInJlZ2lvbl9yZW5kZXIiOiJpYWQifQ==
visitor-hmacdd1bf6f24ae0451d3fc08f1c1d1431663739d3ce63e46b9e7b3f9bc528601adf
hovercard-subject-tagpull_request:3249034302
github-keyboard-shortcutsrepository,pull-request-list,pull-request-conversation,pull-request-files-changed,copilot
google-site-verificationApib7-x98H0j5cPqHWwSMm6dNU4GmODRoqxLiDzdx9I
octolytics-urlhttps://collector.github.com/github/collect
analytics-location///voltron/pull_requests_fragments/pull_request_layout
fb:app_id1401488693436528
apple-itunes-appapp-id=1477376905, app-argument=https://github.com/_view_fragments/voltron/pull_requests/show/python/mypy/20744/pull_request_layout
twitter:imagehttps://opengraph.githubassets.com/a717518a0ba53a773b34b0973743589be89d0e9e18ff4a6d98ad1a999e8c2d20/python/mypy/pull/20744
twitter:cardsummary_large_image
og:imagehttps://opengraph.githubassets.com/a717518a0ba53a773b34b0973743589be89d0e9e18ff4a6d98ad1a999e8c2d20/python/mypy/pull/20744
og:image:altI realised there is a simpler and more complete approach than the one taken in #19600. This adds the new "Step 2" to the original code. Best way to review the diff is probably to check it...
og:image:width1200
og:image:height600
og:site_nameGitHub
og:typeobject
og:author:usernamehauntsaninja
hostnamegithub.com
expected-hostnamegithub.com
None49c8c15fabcbf356d607a90ca115c13b273e42ff8b74155de050fd229a9b0121
turbo-cache-controlno-cache
go-importgithub.com/python/mypy git https://github.com/python/mypy.git
octolytics-dimension-user_id1525981
octolytics-dimension-user_loginpython
octolytics-dimension-repository_id7053637
octolytics-dimension-repository_nwopython/mypy
octolytics-dimension-repository_publictrue
octolytics-dimension-repository_is_forkfalse
octolytics-dimension-repository_network_root_id7053637
octolytics-dimension-repository_network_root_nwopython/mypy
turbo-body-classeslogged-out env-production page-responsive
disable-turbofalse
browser-stats-urlhttps://api.github.com/_private/browser/stats
browser-errors-urlhttps://api.github.com/_private/browser/errors
release3fb1f684e7a833eb1b2d01d39875a2b52cb4fe9b
ui-targetcanary-1
theme-color#1e2327
color-schemelight dark

Links:

Skip to contenthttps://github.com/python/mypy/pull/20744#start-of-content
https://github.com/
Sign in https://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Fpython%2Fmypy%2Fpull%2F20744
GitHub CopilotWrite better code with AIhttps://github.com/features/copilot
GitHub Copilot appDirect agents from issue to mergehttps://github.com/features/ai/github-app
MCP RegistryNewIntegrate external toolshttps://github.com/mcp
ActionsAutomate any workflowhttps://github.com/features/actions
CodespacesInstant dev environmentshttps://github.com/features/codespaces
IssuesPlan and track workhttps://github.com/features/issues
Code ReviewManage code changeshttps://github.com/features/code-review
GitHub Advanced SecurityFind and fix vulnerabilitieshttps://github.com/security/advanced-security
Code securitySecure your code as you buildhttps://github.com/security/advanced-security/code-security
Secret protectionStop leaks before they starthttps://github.com/security/advanced-security/secret-protection
Why GitHubhttps://github.com/why-github
Documentationhttps://docs.github.com
Bloghttps://github.blog
Changeloghttps://github.blog/changelog
Marketplacehttps://github.com/marketplace
View all featureshttps://github.com/features
Enterpriseshttps://github.com/enterprise
Small and medium teamshttps://github.com/team
Startupshttps://github.com/enterprise/startups
Nonprofitshttps://github.com/solutions/industry/nonprofits
App Modernizationhttps://github.com/solutions/use-case/app-modernization
DevSecOpshttps://github.com/solutions/use-case/devsecops
DevOpshttps://github.com/solutions/use-case/devops
CI/CDhttps://github.com/solutions/use-case/ci-cd
View all use caseshttps://github.com/solutions/use-case
Healthcarehttps://github.com/solutions/industry/healthcare
Financial serviceshttps://github.com/solutions/industry/financial-services
Manufacturinghttps://github.com/solutions/industry/manufacturing
Governmenthttps://github.com/solutions/industry/government
View all industrieshttps://github.com/solutions/industry
View all solutionshttps://github.com/solutions
AIhttps://github.com/resources/articles?topic=ai
Software Developmenthttps://github.com/resources/articles?topic=software-development
DevOpshttps://github.com/resources/articles?topic=devops
Securityhttps://github.com/resources/articles?topic=security
View all topicshttps://github.com/resources/articles
Customer storieshttps://github.com/customer-stories
Events & webinarshttps://github.com/resources/events
Ebooks & reportshttps://github.com/resources/whitepapers
Business insightshttps://github.com/solutions/executive-insights
GitHub Skillshttps://skills.github.com
Documentationhttps://docs.github.com
Customer supporthttps://support.github.com
Community forumhttps://github.com/orgs/community/discussions
Trust centerhttps://github.com/trust-center
Partnershttps://github.com/partners
View all resourceshttps://github.com/resources
GitHub SponsorsFund open source developershttps://github.com/open-source/sponsors
Security Labhttps://securitylab.github.com
Maintainer Communityhttps://maintainers.github.com
Acceleratorhttps://github.com/open-source/accelerator
GitHub Starshttps://stars.github.com
Archive Programhttps://archiveprogram.github.com
Topicshttps://github.com/topics
Trendinghttps://github.com/trending
Collectionshttps://github.com/collections
Enterprise platformAI-powered developer platformhttps://github.com/enterprise
GitHub Advanced SecurityEnterprise-grade security featureshttps://github.com/security/advanced-security
Copilot for BusinessEnterprise-grade AI featureshttps://github.com/features/copilot/copilot-business
Premium SupportEnterprise-grade 24/7 supporthttps://github.com/enterprise/premium-support
Pricinghttps://github.com/pricing
Search syntax tipshttps://docs.github.com/search-github/github-code-search/understanding-github-code-search-syntax
documentationhttps://docs.github.com/search-github/github-code-search/understanding-github-code-search-syntax
Sign in https://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Fpython%2Fmypy%2Fpull%2F20744
Sign up https://github.com/signup?ref_cta=Sign+up&ref_loc=header+logged+out&ref_page=%2F%3Cuser-name%3E%2F%3Crepo-name%3E%2Fvoltron%2Fpull_requests_fragments%2Fpull_request_layout&source=header-repo&source_repo=python%2Fmypy
Reloadhttps://github.com/python/mypy/pull/20744
Reloadhttps://github.com/python/mypy/pull/20744
Reloadhttps://github.com/python/mypy/pull/20744
Please reload this pagehttps://github.com/python/mypy/pull/20744
python https://github.com/python
mypyhttps://github.com/python/mypy
Please reload this pagehttps://github.com/python/mypy/pull/20744
Notifications https://github.com/login?return_to=%2Fpython%2Fmypy
Fork 3.2k https://github.com/login?return_to=%2Fpython%2Fmypy
Star 20.5k https://github.com/login?return_to=%2Fpython%2Fmypy
Code https://github.com/python/mypy
Issues 2.7k https://github.com/python/mypy/issues
Pull requests 465 https://github.com/python/mypy/pulls
Actions https://github.com/python/mypy/actions
Projects https://github.com/python/mypy/projects
Wiki https://github.com/python/mypy/wiki
Security and quality 0 https://github.com/python/mypy/security
Insights https://github.com/python/mypy/pulse
Code https://github.com/python/mypy
Issues https://github.com/python/mypy/issues
Pull requests https://github.com/python/mypy/pulls
Actions https://github.com/python/mypy/actions
Projects https://github.com/python/mypy/projects
Wiki https://github.com/python/mypy/wiki
Security and quality https://github.com/python/mypy/security
Insights https://github.com/python/mypy/pulse
hauntsaninjahttps://github.com/hauntsaninja
python:masterhttps://github.com/python/mypy/tree/master
hauntsaninja:matchtuphttps://github.com/hauntsaninja/mypy/tree/matchtup
Conversationhttps://github.com/python/mypy/pull/20744
Commits3 (3)https://github.com/python/mypy/pull/20744/commits
Checkshttps://github.com/python/mypy/pull/20744/checks
Files changedhttps://github.com/python/mypy/pull/20744/files
Further improve match statement narrowing against unionshttps://github.com/python/mypy/pull/20744#top
hauntsaninjahttps://github.com/hauntsaninja
python:masterhttps://github.com/python/mypy/tree/master
hauntsaninja:matchtuphttps://github.com/hauntsaninja/mypy/tree/matchtup
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
Feb 5, 2026https://github.com/python/mypy/pull/20744#issue-3900233979
Please reload this pagehttps://github.com/python/mypy/pull/20744
#19600https://github.com/python/mypy/pull/19600
#19600https://github.com/python/mypy/pull/19600
#15190https://github.com/python/mypy/issues/15190
#17549https://github.com/python/mypy/issues/17549
#17600https://github.com/python/mypy/pull/17600
#18039https://github.com/python/mypy/issues/18039
#19081https://github.com/python/mypy/issues/19081
Please reload this pagehttps://github.com/python/mypy/pull/20744
https://github.com/hauntsaninja
Further improve match statement narrowing against unionshttps://github.com/python/mypy/pull/20744/commits/d2dd89efe5660f04a1416e9a03404197b055a199
d2dd89ehttps://github.com/python/mypy/pull/20744/commits/d2dd89efe5660f04a1416e9a03404197b055a199
python#19600https://github.com/python/mypy/pull/19600
https://github.com/apps/github-actions
Sign in to viewhttps://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Fpython%2Fmypy%2Fpull%2F20744
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
February 5, 2026 08:24https://github.com/python/mypy/pull/20744#event-22551263789
https://github.com/hauntsaninja
another testhttps://github.com/python/mypy/pull/20744/commits/7bba46d5859d168e74903ccde665166b7d3bc6d7
7bba46dhttps://github.com/python/mypy/pull/20744/commits/7bba46d5859d168e74903ccde665166b7d3bc6d7
https://github.com/apps/github-actions
github-actionshttps://github.com/apps/github-actions
Feb 5, 2026 https://github.com/python/mypy/pull/20744#ref-issue-3903627137
Check #20744 sterliakov/mypy-issues#265 https://github.com/sterliakov/mypy-issues/issues/265
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
Feb 5, 2026 https://github.com/python/mypy/pull/20744#ref-issue-2613584095
Can't infer tuple inside match case #18039 https://github.com/python/mypy/issues/18039
https://github.com/apps/github-actions
Sign in to viewhttps://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Fpython%2Fmypy%2Fpull%2F20744
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
February 5, 2026 21:40https://github.com/python/mypy/pull/20744#event-22571957017
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
Feb 5, 2026 https://github.com/python/mypy/pull/20744#ref-issue-3802163929
Better narrowing #20564 https://github.com/python/mypy/issues/20564
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
JukkaLhttps://github.com/JukkaL
February 5, 2026 22:58https://github.com/python/mypy/pull/20744#event-22573480938
https://github.com/JukkaL
JukkaLhttps://github.com/JukkaL
Feb 11, 2026 https://github.com/python/mypy/pull/20744#pullrequestreview-3785863746
View reviewed changes https://github.com/python/mypy/pull/20744/files/7bba46d5859d168e74903ccde665166b7d3bc6d7
JukkaLhttps://github.com/JukkaL
https://github.com/python/mypy/pull/20744#pullrequestreview-3785863746
Learn morehttps://docs.github.com/articles/managing-disruptive-comments/#hiding-a-comment
Please reload this pagehttps://github.com/python/mypy/pull/20744
mypy/checkpattern.pyhttps://github.com/python/mypy/pull/20744/files/7bba46d5859d168e74903ccde665166b7d3bc6d7#diff-899f1e6b7a4d5a6697e7a47731ebcf92a1ce845b5f5fc0b70e3f7ebbef10d7c1
JukkaLhttps://github.com/JukkaL
Feb 11, 2026https://github.com/python/mypy/pull/20744#discussion_r2794223423
Learn morehttps://docs.github.com/articles/managing-disruptive-comments/#hiding-a-comment
Please reload this pagehttps://github.com/python/mypy/pull/20744
https://github.com/hauntsaninja
.https://github.com/python/mypy/pull/20744/commits/dd0b249e046e6c581c9ab84afb91d112c696bcd4
dd0b249https://github.com/python/mypy/pull/20744/commits/dd0b249e046e6c581c9ab84afb91d112c696bcd4
https://github.com/apps/github-actions
github-actionshttps://github.com/apps/github-actions
Feb 11, 2026https://github.com/python/mypy/pull/20744#issuecomment-3886533617
mypy_primerhttps://github.com/hauntsaninja/mypy_primer
Please reload this pagehttps://github.com/python/mypy/pull/20744
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
9752e19https://github.com/python/mypy/commit/9752e1968e9224d2ead4f0cdfd5ff3791ab21b35
Feb 11, 2026https://github.com/python/mypy/pull/20744#event-22714397610
Please reload this pagehttps://github.com/python/mypy/pull/20744
https://github.com/hauntsaninja
hauntsaninjahttps://github.com/hauntsaninja
February 11, 2026 19:39https://github.com/python/mypy/pull/20744#event-22714398460
Mypy doesn't narrow a matched object's type (generic or not) based on attribute subpattern match #19081 https://github.com/python/mypy/issues/19081
Better match narrowing for irrefutable mapping patterns #20906 https://github.com/python/mypy/pull/20906
hauntsaninjahttps://github.com/hauntsaninja
Mar 4, 2026 https://github.com/python/mypy/pull/20744#ref-commit-e413220
https://github.com/hauntsaninja
Better match narrowing for irrefutable mapping patterns (https://github.com/python/mypy/commit/e413220e0e9027c6bfd1551d12e65df7b1740948
#20906https://github.com/python/mypy/pull/20906
)https://github.com/python/mypy/commit/e413220e0e9027c6bfd1551d12e65df7b1740948
e413220https://github.com/python/mypy/commit/e413220e0e9027c6bfd1551d12e65df7b1740948
#18950https://github.com/python/mypy/issues/18950
#19081 (comment)https://github.com/python/mypy/issues/19081#issuecomment-2920053885
#20744https://github.com/python/mypy/pull/20744
#20782https://github.com/python/mypy/pull/20782
https://github.co/hiddenchars
https://github.com/python/mypy/pull/{{ revealButtonHref }}
Sign up for freehttps://github.com/join?source=comment-repo
Sign in to commenthttps://github.com/login?return_to=https%3A%2F%2Fgithub.com%2Fpython%2Fmypy%2Fpull%2F20744
https://github.com/JukkaL
JukkaL https://github.com/JukkaL
https://github.com/python/mypy/pull/20744/files/7bba46d5859d168e74903ccde665166b7d3bc6d7
Can't infer tuple inside match case https://github.com/python/mypy/issues/18039
Type is not being narrowed properly in match statement https://github.com/python/mypy/issues/17549
Unable to narrow the type of a tagged union when using a match statement https://github.com/python/mypy/issues/15190
Please reload this pagehttps://github.com/python/mypy/pull/20744
https://github.com/hauntsaninja
https://github.com/JukkaL
https://github.com
Termshttps://docs.github.com/site-policy/github-terms/github-terms-of-service
Privacyhttps://docs.github.com/site-policy/privacy-policies/github-privacy-statement
Securityhttps://github.com/security
Statushttps://www.githubstatus.com/
Communityhttps://github.community/
Docshttps://docs.github.com/
Contacthttps://support.github.com?tags=dotcom-footer

Viewport: width=device-width

URLs of crawlers that visited me.