fix(core): Bail out of atom.write when atom update and current value are equal

[Thisen]

Fixes #877.

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/pmndrs/jotai/4uTjLF441ENN7W5dE37GdVxYLATU
✅ Preview: https://jotai-git-fix-handle-dependencies-in-derived-chains-pmndrs.vercel.app

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 45e60f6:

Sandbox	Source
React	Configuration
React Typescript	Configuration
React Browserify	Configuration
React Snowpack	Configuration
Next.js	Configuration
Next.js with custom Babel config	Configuration
React with custom Babel config	Configuration
jotai-demo (forked)	Issue #877
jotai-demo (forked)	Issue #877

[github-actions]

Size Change: +39 B (0%)

Total Size: 41.7 kB

Filename	Size	Change
dist/esm/index.js	4.41 kB	+20 B (0%)
dist/index.js	5.25 kB	+19 B (0%)

ℹ️ View Unchanged

Filename	Size
dist/babel/plugin-debug-label.js	794 B
dist/babel/plugin-react-refresh.js	947 B
dist/babel/preset.js	1.21 kB
dist/devtools.js	1.73 kB
dist/esm/babel/plugin-debug-label.js	622 B
dist/esm/babel/plugin-react-refresh.js	763 B
dist/esm/babel/preset.js	1.01 kB
dist/esm/devtools.js	1.58 kB
dist/esm/immer.js	597 B
dist/esm/optics.js	644 B
dist/esm/query.js	1.25 kB
dist/esm/redux.js	251 B
dist/esm/urql.js	1.49 kB
dist/esm/utils.js	4.49 kB
dist/esm/valtio.js	526 B
dist/esm/xstate.js	1.13 kB
dist/esm/zustand.js	284 B
dist/immer.js	732 B
dist/optics.js	938 B
dist/query.js	1.36 kB
dist/redux.js	314 B
dist/urql.js	1.54 kB
dist/utils.js	5.72 kB
dist/valtio.js	586 B
dist/xstate.js	1.19 kB
dist/zustand.js	344 B

_{compressed-size-action}

[dai-shi]

Great work!!!
So, setAtomPromiseOrValue bails out for non-promise values, but we are invoking invalidateDependents anyway, which causes this behavior. This is partly my intention, but overlooked the reported behavior.

[dai-shi]

Thanks again for this! This is new to me and motivates me to investigate some more, because I feel like having some other bugs. I will try.