970fd0a891
Change-Id: I6d08379835160dfb941fe45e708cfc2f942acfbf Reviewed-on: https://cl.tvl.fyi/c/depot/+/8471 Autosubmit: Profpatsch <mail@profpatsch.de> Tested-by: BuildkiteCI Reviewed-by: Profpatsch <mail@profpatsch.de>
355 lines
12 KiB
YAML
355 lines
12 KiB
YAML
# HLint configuration file
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# https://github.com/ndmitchell/hlint
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# Run `hlint --default` to see the example configuration file.
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##########################
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# WARNING: These need to be synced with the default-extensions field
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# in the cabal file.
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- arguments: [-XGHC2021, -XOverloadedRecordDot]
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# Ignore some builtin hints
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# often functions are more readable with explicit arguments
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- ignore: { name: Eta reduce }
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# these redundancy warnings are just completely irrelevant
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- ignore: { name: Redundant bracket }
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- ignore: { name: Move brackets to avoid $ }
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- ignore: { name: Redundant $ }
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- ignore: { name: Redundant do }
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- ignore: { name: Redundant multi-way if }
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# allow case-matching on bool, because why not
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- ignore: { name: Use if }
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# hlint cannot distinguish actual newtypes from data types
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# that accidentally have only one field
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# (but might have more in the future).
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# Since it’s a mostly irrelevant runtime optimization, we don’t care.
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- ignore: { name: Use newtype instead of data }
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# these lead to harder-to-read/more implicit code
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- ignore: { name: Use fmap }
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- ignore: { name: Use <$> }
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- ignore: { name: Use tuple-section }
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- ignore: { name: Use forM_ }
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# fst and snd are usually a code smell and should be explicit matches, _naming the ignored side.
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- ignore: { name: Use fst }
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- ignore: { name: Use snd }
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- ignore: { name: Use fromMaybe }
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- ignore: { name: Use const }
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- ignore: { name: Replace case with maybe }
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- ignore: { name: Replace case with fromMaybe }
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- ignore: { name: Avoid lambda }
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- ignore: { name: Avoid lambda using `infix` }
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- ignore: { name: Use curry }
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- ignore: { name: Use uncurry }
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- ignore: { name: Use first }
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- ignore: { name: Redundant first }
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- ignore: { name: Use second }
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- ignore: { name: Use bimap }
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# just use `not x`
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- ignore: { name: Use unless }
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- ignore: { name: Redundant <&> }
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# list comprehensions are a seldomly used part of the Haskell language
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# and they introduce syntactic overhead that is usually not worth the conciseness
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- ignore: { name: Use list comprehension }
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# Seems to be buggy in cases
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- ignore: { name: Use section }
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# multiple maps in a row are usually used for clarity,
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# and the compiler will optimize them away, thank you very much.
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- ignore: { name: Use map once }
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- ignore: { name: Fuse foldr/map }
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- ignore: { name: Fuse traverse/map }
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- ignore: { name: Fuse traverse_/map }
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# this is silly, why would I use a special function if I can just (heh) `== Nothing`
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- ignore: { name: Use isNothing }
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# The duplication heuristic is not very smart
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# and more annoying than helpful.
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# see https://github.com/ndmitchell/hlint/issues/1009
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- ignore: { name: Reduce duplication }
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# Stops the pattern match trick
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- ignore: { name: Use record patterns }
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- ignore: { name: Use null }
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- ignore: { name: Use uncurry }
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# we don’t want void, see below
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- ignore: { name: Use void }
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- functions:
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# disallow Enum instance functions, they are partial
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- name: Prelude.succ
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within: [Relude.Extra.Enum]
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message: "Dangerous, will fail for highest element"
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- name: Prelude.pred
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within: [Relude.Extra.Enum]
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message: "Dangerous, will fail for lowest element"
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- name: Prelude.toEnum
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within: []
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message: "Extremely partial"
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- name: Prelude.fromEnum
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within: []
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message: "Dangerous for most uses"
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- name: Prelude.enumFrom
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within: []
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- name: Prelude.enumFromThen
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within: []
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- name: Prelude.enumFromThenTo
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within: []
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- name: Prelude.oundedEnumFrom
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within: []
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- name: Prelude.boundedEnumFromThen
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within: []
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- name: Text.Read.readMaybe
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within:
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# The BSON ObjectId depends on Read for parsing
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- Milkmap.Milkmap
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- Milkmap.FieldData.Value
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message: "`readMaybe` is probably not what you want for parsing values, please use the `FieldParser` module."
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# `void` discards its argument and is polymorphic,
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# thus making it brittle in the face of code changes.
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# (see https://tech.freckle.com/2020/09/23/void-is-a-smell/)
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# Use an explicit `_ <- …` instead.
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- name: Data.Functor.void
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within: []
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message: "`void` leads to bugs. Use an explicit `_ <- …` instead"
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- name: Data.Foldable.length
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within: []
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message: "`Data.Foldable.length` is dangerous to use, because it also works on types you wouldn’t expect, like `length (3,4) == 1` and `length (Just 2) == 1`. Use the `length` function for your specific type instead, for example `List.length` or `Map.length`."
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- name: Prelude.length
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within: []
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message: "`Prelude.length` is dangerous to use, because it also works on types you wouldn’t expect, like `length (3,4) == 1` and `length (Just 2) == 1`. Use the `length` function for your specific type instead, for example `List.length` or `Map.length`."
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# Using an explicit lambda with its argument “underscored”
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# is more clear in every case.
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# e.g. `const True` => `\_request -> True`
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# shows the reader that the ignored argument was a request.
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- name: Prelude.const
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within: []
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message: "Replace `const` with an explicit lambda with type annotation for code clarity and type safety, e.g.: `const True` => `\\(_ :: Request) -> True`. If you really don’t want to spell out the type (which might lead to bugs!), you can also use something like `\_request -> True`."
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- name: Data.List.nub
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within: []
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message: "O(n²), use `Data.Containers.ListUtils.nubOrd"
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- name: Prelude.maximum
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within: []
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message: "`maximum` crashes on empty list; use non-empty lists and `maximum1`"
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- name: Data.List.maximum
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within: []
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message: "`maximum` crashes on empty list; use non-empty lists and `maximum1`"
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- name: Prelude.minimum
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within: []
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message: "`minimum` crashes on empty list; use non-empty lists and `minimum1`"
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- name: Data.List.minimum
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within: []
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message: "`minimum` crashes on empty list; use non-empty lists and `minimum1`"
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- name: Data.Foldable.maximum
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within: []
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message: "`maximum` crashes on empty foldable stucture; use Foldable1 and `maximum1`."
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- name: Data.Foldable.minimum
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within: []
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message: "`minimum` crashes on empty foldable stucture; use Foldable1 and `minimum1`."
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# Using prelude functions instead of stdlib functions
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- name: "Data.Text.Encoding.encodeUtf8"
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within: ["MyPrelude"]
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message: "Use `textToBytesUtf8`"
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- name: "Data.Text.Lazy.Encoding.encodeUtf8"
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within: ["MyPrelude"]
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message: "Use `textToBytesUtf8Lazy`"
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- name: "Data.Text.Encoding.decodeUtf8'"
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within: ["MyPrelude"]
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message: "Use `bytesToTextUtf8`"
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- name: "Data.Text.Encoding.Lazy.decodeUtf8'"
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within: ["MyPrelude"]
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message: "Use `bytesToTextUtf8Lazy`"
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- name: "Data.Text.Encoding.decodeUtf8"
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within: ["MyPrelude"]
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message: "Either check for errors with `bytesToTextUtf8`, decode leniently with unicode replacement characters with `bytesToTextUtf8Lenient` or use the crashing version `bytesToTextUtf8Unsafe` (discouraged)."
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- name: "Data.Text.Encoding.Lazy.decodeUtf8"
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within: ["MyPrelude"]
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message: "Either check for errors with `bytesToTextUtf8Lazy`, decode leniently with unicode replacement characters with `bytesToTextUtf8LenientLazy` or use the crashing version `bytesToTextUtf8UnsafeLazy` (discouraged)."
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- name: "Data.Text.Lazy.toStrict"
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within: ["MyPrelude"]
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message: "Use `toStrict`"
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- name: "Data.Text.Lazy.fromStrict"
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within: ["MyPrelude"]
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message: "Use `toLazy`"
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- name: "Data.ByteString.Lazy.toStrict"
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within: ["MyPrelude"]
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message: "Use `toStrictBytes`"
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- name: "Data.ByteString.Lazy.fromStrict"
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within: ["MyPrelude"]
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message: "Use `toLazyBytes`"
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- name: "Data.Text.unpack"
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within: ["MyPrelude"]
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message: "Use `textToString`"
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- name: "Data.Text.pack"
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within: ["MyPrelude"]
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message: "Use `stringToText`"
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- name: "Data.Maybe.listToMaybe"
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within: []
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message: |
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`listToMaybe`` throws away everything but the first element of a list (it is essentially `safeHead`).
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If that is what you want, please use a pattern match like
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```
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case xs of
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[] -> …
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(x:_) -> …
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```
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- name: "Data.List.head"
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within: []
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message: |
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`List.head` fails on an empty list. I didn’t think I have to say this, but please use a pattern match on the list, like:
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```
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case xs of
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[] -> … error handling …
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(x:_) -> …
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```
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Also think about why the rest of the list should be ignored.
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- name: "Prelude.head"
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within: []
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message: |
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`List.head` fails on an empty list. I didn’t think I have to say this, but please use a pattern match on the list, like.
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```
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case xs of
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[] -> … error handling …
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(x:_) -> …
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```
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Also think about why the rest of the list should be ignored.
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- name: "Data.Maybe.fromJust"
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within: []
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message: |
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`Maybe.fromJust` is obviously partial. Please use a pattern match.
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In case you actually want to throw an error on an empty list,
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please add an error message, like so:
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```
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myMaybe & annotate "my error message" & unwrapError
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```
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If you are in `IO`, use `unwrapIOError` instead,
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or throw a monad-specific error.
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- name: "Data.Either.fromLeft"
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within: []
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message: |
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`Either.fromLeft` is obviously partial. Please use a pattern match.
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- name: "Data.Either.fromRight"
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within: []
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message: |
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`Either.fromRight` is obviously partial. Please use a pattern match.
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# Make restricted functions into an error if found
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- error: { name: "Avoid restricted function, see comment in .hlint.yaml" }
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# Some functions that have (more modern) aliases.
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# They are not dangerous per se,
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# but we want to make it easier to read our code so we should
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# make sure we don’t use too many things that are renames.
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- hint:
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lhs: "undefined"
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rhs: "todo"
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note: "`undefined` is a silent error, `todo` will display a warning as long as it exists in the code."
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- hint:
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lhs: "return"
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rhs: "pure"
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note: "Use `pure` from `Applicative` instead, it’s the exact same function."
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- hint:
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lhs: "mapM"
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rhs: "traverse"
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note: "Use `traverse` from `Traversable` instead. It’s the exact same function."
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- hint:
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lhs: "mapM_"
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rhs: "traverse_"
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note: "Use `traverse_` from `Traversable` instead. It’s the exact same function."
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- hint:
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lhs: "forM"
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rhs: "for"
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note: "Use `for` from `Traversable` instead. It’s the exact same function."
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- hint:
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lhs: "forM_"
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rhs: "for_"
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note: "Use `for_` from `Traversable` instead. It’s the exact same function."
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- hint:
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lhs: "stringToText (show x)"
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rhs: "showToText x"
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- hint:
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lhs: "Data.Set.toList (Data.Set.fromList x)"
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rhs: "List.nubOrd x"
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note: "`nubOrd` removes duplicate elements from a list."
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- modules:
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# Disallowed Modules
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- name: Data.Map
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within: []
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message: "Lazy maps leak space, use `import Data.Map.Strict as Map` instead"
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- name: Control.Monad.Writer
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within: []
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message: "Lazy writers leak space, use `Control.Monad.Trans.Writer.CPS` instead"
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- name: Control.Monad.Trans.Writer.Lazy
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within: []
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message: "Lazy writers leak space, use `Control.Monad.Trans.Writer.CPS` instead"
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- name: Control.Monad.Trans.Writer.Strict
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within: []
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message: "Even strict writers leak space, use `Control.Monad.Trans.Writer.CPS` instead"
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# Qualified module imports
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- { name: Data.Map.Strict, as: Map }
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- { name: Data.HashMap.Strict, as: HashMap }
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- { name: Data.Set, as: Set }
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- { name: Data.ByteString.Char8, as: Char8 }
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- { name: Data.ByteString.Lazy.Char8, as: Char8.Lazy }
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- { name: Data.Text, as: Text }
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- { name: Data.Vector, as: Vector }
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- { name: Data.Vault.Lazy, as: Vault }
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- { name: Data.Aeson, as: Json }
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- { name: Data.Aeson.Types, as: Json }
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- { name: Data.Aeson.BetterErrors as Json }
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