How can my Haskell program or library find its version number- How can my Haskell program or library find its version number?

problem ：

I would like my cabalised program to have a --version switch. I hope my cabalised The program has a --version Switch .

I would like it to report the same version as is present in the .cabal file. I hope it reports with .cabal The same version exists in the file .

If I have to update the version number separately in my Haskell source code as well as in the .cabal file, I will eventually get them out of sync. If I have to be in my Haskell The source code and .cabal The version number is updated separately in the document , I will eventually make them out of sync .

So, how can my program, while being compiled under cabal, get its version number from the .cabal file? that , How is my program in cabal Compile below , from .cabal Get its version number from the file ？

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Solution ：

Reference resources ： https://stackoom.com/en/question/C8Uc