Where can I find correct package name and version for Haskell?

Question

Say, I need System.Eval.Haskell. Or whatever else. How do I know which package I should specify in my package.yaml? When I go to the https://hackage.haskell.org/package/plugins-1.5.7/docs/System-Eval-Haskell.html, I see no package name.

P.S. "plugins" did not work for me. Thus, I assume it's something different. I hope so :)

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Looks like there is somewhat quite unclear difference between extra-dependencies and "regular" dependencies in the configuration. Mentioning plugins-1.5.7 as extra-dep indeed works. Am I doing some dependency mismanagement here, or that's green way to go?

Answer 1

When you view module documentation on hackage, the package name is in the upper left corner:

In this case, it's indeed plugins, version 1.5.7.

When you declare dependencies in your .cabal file, Stack will attempt to find a version that fits with the Long-Term Support (LTS) collection that you're targeting.

Sometimes, you want to use a different version than the one available in the LTS collection (for example if you want a more recent one), in which case you can define the package, and its specific version, in extra-dependencies.