Safe Haskell	Safe-Inferred
Language	Haskell2010

Ouroboros.Consensus.Util.RedundantConstraints

Contents

Convenience re-export

Synopsis

keepRedundantConstraint ∷ c ⇒ proxy c → ()
data Proxy (t ∷ k) = Proxy

Documentation

keepRedundantConstraint ∷ c ⇒ proxy c → () Source #

Can be used to silence individual "redundant constraint" warnings

foo :: ConstraintUsefulForDebugging => ...
foo =
    ..
  where
    _ = keepRedundantConstraint (Proxy @ConstraintUsefulForDebugging))

Convenience re-export

data Proxy (t ∷ k) #

Proxy is a type that holds no data, but has a phantom parameter of arbitrary type (or even kind). Its use is to provide type information, even though there is no value available of that type (or it may be too costly to create one).

Historically, Proxy :: Proxy a is a safer alternative to the undefined :: a idiom.

>>> Proxy :: Proxy (Void, Int -> Int)
Proxy

Proxy can even hold types of higher kinds,

>>> Proxy :: Proxy Either
Proxy

>>> Proxy :: Proxy Functor
Proxy

>>> Proxy :: Proxy complicatedStructure
Proxy

Constructors

Proxy

Instances

Instances details

Generic1 (Proxy ∷ k → Type)
Instance details Defined in GHC.Generics Associated Types type Rep1 Proxy ∷ k → Type # Methods from1 ∷ ∀ (a ∷ k0). Proxy a → Rep1 Proxy a # to1 ∷ ∀ (a ∷ k0). Rep1 Proxy a → Proxy a #
RepeatWithIndex Void (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods irepeat ∷ (Void → a) → Proxy a Source #
SemialignWithIndex Void (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods ialignWith ∷ (Void → These a b → c) → Proxy a → Proxy b → Proxy c Source #
ZipWithIndex Void (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods izipWith ∷ (Void → a → b → c) → Proxy a → Proxy b → Proxy c Source #
Foldable (Proxy ∷ Type → Type)	Since: base-4.7.0.0
Instance details Defined in Data.Foldable Methods fold ∷ Monoid m ⇒ Proxy m → m # foldMap ∷ Monoid m ⇒ (a → m) → Proxy a → m # foldMap' ∷ Monoid m ⇒ (a → m) → Proxy a → m # foldr ∷ (a → b → b) → b → Proxy a → b # foldr' ∷ (a → b → b) → b → Proxy a → b # foldl ∷ (b → a → b) → b → Proxy a → b # foldl' ∷ (b → a → b) → b → Proxy a → b # foldr1 ∷ (a → a → a) → Proxy a → a # foldl1 ∷ (a → a → a) → Proxy a → a # toList ∷ Proxy a → [a] # null ∷ Proxy a → Bool # length ∷ Proxy a → Int # elem ∷ Eq a ⇒ a → Proxy a → Bool # maximum ∷ Ord a ⇒ Proxy a → a # minimum ∷ Ord a ⇒ Proxy a → a # sum ∷ Num a ⇒ Proxy a → a # product ∷ Num a ⇒ Proxy a → a #
Eq1 (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftEq ∷ (a → b → Bool) → Proxy a → Proxy b → Bool #
Ord1 (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftCompare ∷ (a → b → Ordering) → Proxy a → Proxy b → Ordering #
Read1 (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftReadsPrec ∷ (Int → ReadS a) → ReadS [a] → Int → ReadS (Proxy a) # liftReadList ∷ (Int → ReadS a) → ReadS [a] → ReadS [Proxy a] # liftReadPrec ∷ ReadPrec a → ReadPrec [a] → ReadPrec (Proxy a) # liftReadListPrec ∷ ReadPrec a → ReadPrec [a] → ReadPrec [Proxy a] #
Show1 (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Classes Methods liftShowsPrec ∷ (Int → a → ShowS) → ([a] → ShowS) → Int → Proxy a → ShowS # liftShowList ∷ (Int → a → ShowS) → ([a] → ShowS) → [Proxy a] → ShowS #
Contravariant (Proxy ∷ Type → Type)
Instance details Defined in Data.Functor.Contravariant Methods contramap ∷ (a' → a) → Proxy a → Proxy a' # (>$) ∷ b → Proxy b → Proxy a #
Traversable (Proxy ∷ Type → Type)	Since: base-4.7.0.0
Instance details Defined in Data.Traversable Methods traverse ∷ Applicative f ⇒ (a → f b) → Proxy a → f (Proxy b) # sequenceA ∷ Applicative f ⇒ Proxy (f a) → f (Proxy a) # mapM ∷ Monad m ⇒ (a → m b) → Proxy a → m (Proxy b) # sequence ∷ Monad m ⇒ Proxy (m a) → m (Proxy a) #
Alternative (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Proxy Methods empty ∷ Proxy a # (<\|>) ∷ Proxy a → Proxy a → Proxy a # some ∷ Proxy a → Proxy [a] # many ∷ Proxy a → Proxy [a] #
Applicative (Proxy ∷ Type → Type)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods pure ∷ a → Proxy a # (<>) ∷ Proxy (a → b) → Proxy a → Proxy b # liftA2 ∷ (a → b → c) → Proxy a → Proxy b → Proxy c # (>) ∷ Proxy a → Proxy b → Proxy b # (<*) ∷ Proxy a → Proxy b → Proxy a #
Functor (Proxy ∷ Type → Type)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods fmap ∷ (a → b) → Proxy a → Proxy b # (<$) ∷ a → Proxy b → Proxy a #
Monad (Proxy ∷ Type → Type)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods (>>=) ∷ Proxy a → (a → Proxy b) → Proxy b # (>>) ∷ Proxy a → Proxy b → Proxy b # return ∷ a → Proxy a #
MonadPlus (Proxy ∷ Type → Type)	Since: base-4.9.0.0
Instance details Defined in Data.Proxy Methods mzero ∷ Proxy a # mplus ∷ Proxy a → Proxy a → Proxy a #
NFData1 (Proxy ∷ Type → Type)	Since: deepseq-1.4.3.0
Instance details Defined in Control.DeepSeq Methods liftRnf ∷ (a → ()) → Proxy a → () #
Hashable1 (Proxy ∷ Type → Type)
Instance details Defined in Data.Hashable.Class Methods liftHashWithSalt ∷ (Int → a → Int) → Int → Proxy a → Int Source #
Align (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods nil ∷ Proxy a Source #
Repeat (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods repeat ∷ a → Proxy a Source #
Semialign (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods align ∷ Proxy a → Proxy b → Proxy (These a b) Source # alignWith ∷ (These a b → c) → Proxy a → Proxy b → Proxy c Source #
Unalign (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods unalign ∷ Proxy (These a b) → (Proxy a, Proxy b) Source # unalignWith ∷ (c → These a b) → Proxy c → (Proxy a, Proxy b) Source #
Unzip (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods unzipWith ∷ (c → (a, b)) → Proxy c → (Proxy a, Proxy b) Source # unzip ∷ Proxy (a, b) → (Proxy a, Proxy b) Source #
Zip (Proxy ∷ Type → Type)
Instance details Defined in Data.Semialign.Internal Methods zip ∷ Proxy a → Proxy b → Proxy (a, b) Source # zipWith ∷ (a → b → c) → Proxy a → Proxy b → Proxy c Source #
Monoid (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods mempty ∷ Proxy s # mappend ∷ Proxy s → Proxy s → Proxy s # mconcat ∷ [Proxy s] → Proxy s #
Semigroup (Proxy s)	Since: base-4.9.0.0
Instance details Defined in Data.Proxy Methods (<>) ∷ Proxy s → Proxy s → Proxy s # sconcat ∷ NonEmpty (Proxy s) → Proxy s # stimes ∷ Integral b ⇒ b → Proxy s → Proxy s #
Bounded (Proxy t)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods minBound ∷ Proxy t # maxBound ∷ Proxy t #
Enum (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods succ ∷ Proxy s → Proxy s # pred ∷ Proxy s → Proxy s # toEnum ∷ Int → Proxy s # fromEnum ∷ Proxy s → Int # enumFrom ∷ Proxy s → [Proxy s] # enumFromThen ∷ Proxy s → Proxy s → [Proxy s] # enumFromTo ∷ Proxy s → Proxy s → [Proxy s] # enumFromThenTo ∷ Proxy s → Proxy s → Proxy s → [Proxy s] #
Generic (Proxy t)
Instance details Defined in GHC.Generics Associated Types type Rep (Proxy t) ∷ Type → Type # Methods from ∷ Proxy t → Rep (Proxy t) x # to ∷ Rep (Proxy t) x → Proxy t #
Ix (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods range ∷ (Proxy s, Proxy s) → [Proxy s] # index ∷ (Proxy s, Proxy s) → Proxy s → Int # unsafeIndex ∷ (Proxy s, Proxy s) → Proxy s → Int # inRange ∷ (Proxy s, Proxy s) → Proxy s → Bool # rangeSize ∷ (Proxy s, Proxy s) → Int # unsafeRangeSize ∷ (Proxy s, Proxy s) → Int #
Read (Proxy t)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods readsPrec ∷ Int → ReadS (Proxy t) # readList ∷ ReadS [Proxy t] # readPrec ∷ ReadPrec (Proxy t) # readListPrec ∷ ReadPrec [Proxy t] #
Show (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods showsPrec ∷ Int → Proxy s → ShowS # show ∷ Proxy s → String # showList ∷ [Proxy s] → ShowS #
NFData (Proxy a)	Since: deepseq-1.4.0.0
Instance details Defined in Control.DeepSeq Methods rnf ∷ Proxy a → () #
Eq (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods (==) ∷ Proxy s → Proxy s → Bool # (/=) ∷ Proxy s → Proxy s → Bool #
Ord (Proxy s)	Since: base-4.7.0.0
Instance details Defined in Data.Proxy Methods compare ∷ Proxy s → Proxy s → Ordering # (<) ∷ Proxy s → Proxy s → Bool # (<=) ∷ Proxy s → Proxy s → Bool # (>) ∷ Proxy s → Proxy s → Bool # (>=) ∷ Proxy s → Proxy s → Bool # max ∷ Proxy s → Proxy s → Proxy s # min ∷ Proxy s → Proxy s → Proxy s #
Hashable (Proxy a)
Instance details Defined in Data.Hashable.Class Methods hashWithSalt ∷ Int → Proxy a → Int Source # hash ∷ Proxy a → Int Source #
Serialise (Proxy a)	Since: serialise-0.2.0.0
Instance details Defined in Codec.Serialise.Class Methods encode ∷ Proxy a → Encoding Source # decode ∷ Decoder s (Proxy a) Source # encodeList ∷ [Proxy a] → Encoding Source # decodeList ∷ Decoder s [Proxy a] Source #
type Rep1 (Proxy ∷ k → Type)	Since: base-4.6.0.0
Instance details Defined in GHC.Generics type Rep1 (Proxy ∷ k → Type) = D1 ('MetaData "Proxy" "Data.Proxy" "base" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 ∷ k → Type))
type Rep (Proxy t)	Since: base-4.6.0.0
Instance details Defined in GHC.Generics type Rep (Proxy t) = D1 ('MetaData "Proxy" "Data.Proxy" "base" 'False) (C1 ('MetaCons "Proxy" 'PrefixI 'False) (U1 ∷ Type → Type))