Safe Haskell	Safe-Inferred
Language	Haskell2010

Stackctl.OneOrListOf

Synopsis

data OneOrListOf a
fromList :: [a] -> OneOrListOf a

Documentation

data OneOrListOf a Source #

Type representing one a or a list of a

This type is isomorphic both NonEmpty a and Either a [a]. Its primary use-case is to parse Yaml (through its FromJSON) where users may specify a list of values, but specifying a single value is worth supporting, typically for backwards-compatibility:

something:
  field:
    - one
    - two

something:
  field: one # => should be treated like field: [one]

The Foldable instance should be used to treat the value like a list, such as extracting it directly via toList.

Implementation note: this type preserves the form in which it was decoded (in other words, it's not a newtype over one of the isomorphic types mentioned above), so that we can encode it back out in the same format.

Instances

Instances details

Foldable OneOrListOf Source #
Instance details Defined in Stackctl.OneOrListOf Methods fold :: Monoid m => OneOrListOf m -> m # foldMap :: Monoid m => (a -> m) -> OneOrListOf a -> m # foldMap' :: Monoid m => (a -> m) -> OneOrListOf a -> m # foldr :: (a -> b -> b) -> b -> OneOrListOf a -> b # foldr' :: (a -> b -> b) -> b -> OneOrListOf a -> b # foldl :: (b -> a -> b) -> b -> OneOrListOf a -> b # foldl' :: (b -> a -> b) -> b -> OneOrListOf a -> b # foldr1 :: (a -> a -> a) -> OneOrListOf a -> a # foldl1 :: (a -> a -> a) -> OneOrListOf a -> a # toList :: OneOrListOf a -> [a] # null :: OneOrListOf a -> Bool # length :: OneOrListOf a -> Int # elem :: Eq a => a -> OneOrListOf a -> Bool # maximum :: Ord a => OneOrListOf a -> a # minimum :: Ord a => OneOrListOf a -> a # sum :: Num a => OneOrListOf a -> a # product :: Num a => OneOrListOf a -> a #
FromJSON a => FromJSON (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Methods parseJSON :: Value -> Parser (OneOrListOf a) # parseJSONList :: Value -> Parser [OneOrListOf a] #
ToJSON a => ToJSON (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Methods toJSON :: OneOrListOf a -> Value # toEncoding :: OneOrListOf a -> Encoding # toJSONList :: [OneOrListOf a] -> Value # toEncodingList :: [OneOrListOf a] -> Encoding #
Semigroup (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Methods (<>) :: OneOrListOf a -> OneOrListOf a -> OneOrListOf a # sconcat :: NonEmpty (OneOrListOf a) -> OneOrListOf a # stimes :: Integral b => b -> OneOrListOf a -> OneOrListOf a #
Generic (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Associated Types type Rep (OneOrListOf a) :: Type -> Type # Methods from :: OneOrListOf a -> Rep (OneOrListOf a) x # to :: Rep (OneOrListOf a) x -> OneOrListOf a #
Show a => Show (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Methods showsPrec :: Int -> OneOrListOf a -> ShowS # show :: OneOrListOf a -> String # showList :: [OneOrListOf a] -> ShowS #
Eq a => Eq (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf Methods (==) :: OneOrListOf a -> OneOrListOf a -> Bool # (/=) :: OneOrListOf a -> OneOrListOf a -> Bool #
type Rep (OneOrListOf a) Source #
Instance details Defined in Stackctl.OneOrListOf type Rep (OneOrListOf a) = D1 ('MetaData "OneOrListOf" "Stackctl.OneOrListOf" "stackctl-1.5.0.1-A2c4YboayP8CnSSTFojgw3" 'False) (C1 ('MetaCons "One" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)) :+: C1 ('MetaCons "List" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 [a])))

fromList :: [a] -> OneOrListOf a Source #