Python Type Hinting and Static Type Checking

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PyCon Korea 2019 ੿੸ ఋੑ Ѩࢎ۽ ؊ ա਷ Python ௏٘ ੘ࢿೞӝ ੉ହ൞

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ߊ಴੗ blurfx • ࣽୌೱ؀೟Ү (2014 ~ ) • ֏ट௏ܻই (2018.03 ~ 2019.07) • ೖ೒ಎ٘ஹಌפ (2019.07 ~ )

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౵੉ॆਸ फযೞח ࢎۈٜ਷ ౵੉ॆਸ ৵ फযೡөਃ?

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੿੸ ఋੑ ঱য  ز੸ ఋੑ ঱য

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੿੸ ఋੑ ঱য Writing Code Build Test Run/Deploy য়ܨܳ ߊѼೞח ҳр

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ز੸ ఋੑ ঱য Writing Code Test Run/Deploy য়ܨܳ ߊѼೞח ҳр

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੿੸ ఋੑ Ѩࢎо ޖ঺੉Ҋ ೞݶ ޖ঺੉ જই૑աਃ?

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೐۽ં౟о ੘ਵݶ ѐߊ੗੄ ࣻب ੸Ҋ, ߡӒ੄ ࣻب ੸૑݅ icons from https://icons8.com

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೐۽ં౟о ੘ਵݶ ѐߊ੗੄ ࣻب ੸Ҋ, ߡӒ੄ ࣻب ੸૑݅ icons from https://icons8.com ೐۽ં౟о ழ૑Ҋ ѐߊ੗о ݆ই૑ݶ Ӓ ݅ఀ ߡӒب ݆ই૘פ׮

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೐۽ં౟о ੘ਵݶ ѐߊ੗੄ ࣻب ੸Ҋ, ߡӒ੄ ࣻب ੸૑݅ icons from https://icons8.com ೐۽ં౟о ழ૑Ҋ ѐߊ੗о ݆ই૑ݶ Ӓ ݅ఀ ߡӒب ݆ই૘פ׮ ز੸ ఋੑ ঱য۽ ੘ࢿೠ ௏٘ח ೐۽ં౟о ழ૕ࣻ۾  п ё୓о যڃ чਸ ঌҊ ੓ח૑ ൨ٜয૘פ׮ var x     ... x ?

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Writing Code Static Type Checking Test Run/Deploy ੿੸ ఋੑ ୓௼۽ ఋੑী য়ܨо ੓ח૑ Ѩࢎ

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௏٘੄ оةࢿ੉ ৢۄоҊ ఋੑਵ۽ ߊࢤೡ ࣻ ੓ח ߡӒܳ ৘ߑ೧઻ਃ

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௏٘੄ оةࢿ੉ ৢۄоҊ ఋੑਵ۽ ߊࢤೡ ࣻ ੓ח ߡӒܳ ৘ߑ೧઻ਃ

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To Type or Not to Type: Quantifying Detectable Bugs in JavaScript http://earlbarr.com/publications/typestudy.pdf

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http://earlbarr.com/publications/typestudy.pdf To Type or Not to Type

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Conclusion: we found that using Flow or TypeScript could have prevented 15% of the public bugs for public projects on GitHub. http://earlbarr.com/publications/typestudy.pdf To Type or Not to Type

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Conclusion: we found that using Flow or TypeScript could have prevented 15% of the public bugs for public projects on GitHub. http://earlbarr.com/publications/typestudy.pdf To Type or Not to Type

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౵੉ॆ਷ ز੸ ఋੑ ঱যੋؘ ఋੑਸ যڌѱ ઻ਃ?

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Function Annotation Type Annotation Variable Annotation Python 3.0+ Python 3.5+ Python 3.6+

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Python 3.6+

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ఋੑ ൦౴

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• ੿ࣻ৬ ޙ੗ৌ݅ ೲਊೞח ܻझ౟ • ޙ੗ৌ, पࣻ, ࠗ਎ ࣽࢲ۽ ػ ౚ೒ • ޙ੗ৌ ః৬ ߄੉౟ чਸ о૓ ٤࣊ցܻ • ઁ֎ܼ ೣࣻ৬ ௿ېझ ఋੑ ൦౴

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https://imgﬂip.com/i/186jmm

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TypeError: Too many parameters for typing.List; actual 2, expected 1 ఋੑ ൦౴

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http://blog.daum.net/junjungirl/109

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“ no type checking happens at runtime ” — PEP 484

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mypy mypy ࢸ஖ೞӝ

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mypy ੿੸ ఋੑ Ѩࢎೞӝ

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mypy ੿੸ ఋੑ Ѩࢎೞӝ

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mypy ੿੸ ఋੑ Ѩࢎೞӝ

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Incompatible types in assignment (expression has type "str", variable has type "int") List item 1 has incompatible type "int"; expected "str" List item 2 has incompatible type "ﬂoat"; expected "str" Argument 1 to "append" of "list" has incompatible type "bytes"; expected "str"