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1. assertPprMaybe :: HasCallStack => Maybe SDoc -> a -> a

   ghc	GHC.Utils.Panic

   No documentation available.

2. annProvenanceName_maybe :: UnXRec p => AnnProvenance p -> Maybe (IdP p)

   ghc	Language.Haskell.Syntax.Decls

   No documentation available.

3. qualifiedDoModuleName_maybe :: HsStmtContext fn -> Maybe ModuleName

   ghc	Language.Haskell.Syntax.Expr

   No documentation available.

4. isFieldMaybe :: FieldDef -> Bool

   persistent	Database.Persist.FieldDef

   Check if the field is `Maybe a`

5. ByMaybeAttr :: WhyNullable

   persistent	Database.Persist.Types

   No documentation available.

6. FieldAttrMaybe :: FieldAttr

   persistent	Database.Persist.Types

   The Maybe keyword goes after the type. This indicates that the column is nullable, and the generated Haskell code will have a Maybe type for it. Example:

   User
   name Text Maybe
   

7. lookupMaybe :: Text -> Form -> Either Text (Maybe Text)

   http-api-data	Web.FormUrlEncoded

   Lookup an optional value for a key. Fail if there is more than one value.

   >>> lookupMaybe "name" []
   Right Nothing
   
   >>> lookupMaybe "name" [("name", "Oleg")]
   Right (Just "Oleg")
   
   >>> lookupMaybe "name" [("name", "Oleg"), ("name", "David")]
   Left "Duplicate key \"name\""
   

8. parseMaybe :: FromHttpApiData v => Text -> Form -> Either Text (Maybe v)

   http-api-data	Web.FormUrlEncoded

   Lookup an optional value for a given key and parse it with parseQueryParam. Fail if there is more than one value for the key.

   >>> parseMaybe "age" [] :: Either Text (Maybe Word8)
   Right Nothing
   
   >>> parseMaybe "age" [("age", "12"), ("age", "25")] :: Either Text (Maybe Word8)
   Left "Duplicate key \"age\""
   
   >>> parseMaybe "age" [("age", "seven")] :: Either Text (Maybe Word8)
   Left "could not parse: `seven' (input does not start with a digit)"
   
   >>> parseMaybe "age" [("age", "777")] :: Either Text (Maybe Word8)
   Left "out of bounds: `777' (should be between 0 and 255)"
   
   >>> parseMaybe "age" [("age", "7")] :: Either Text (Maybe Word8)
   Right (Just 7)
   

9. parseHeaderMaybe :: FromHttpApiData a => ByteString -> Maybe a

   http-api-data	Web.HttpApiData

   Parse HTTP header value in a Maybe.

   >>> parseHeaderMaybe "hello" :: Maybe Text
   Just "hello"
   

10. parseQueryParamMaybe :: FromHttpApiData a => Text -> Maybe a

    http-api-data	Web.HttpApiData

    Parse query param value in a Maybe.

    >>> parseQueryParamMaybe "true" :: Maybe Bool
    Just True
    

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