planet-mitchell-0.0.0: Planet Mitchell

Safe HaskellSafe
LanguageHaskell2010

Read

Synopsis

Documentation

class Read a where #

Parsing of Strings, producing values.

Derived instances of Read make the following assumptions, which derived instances of Show obey:

  • If the constructor is defined to be an infix operator, then the derived Read instance will parse only infix applications of the constructor (not the prefix form).
  • Associativity is not used to reduce the occurrence of parentheses, although precedence may be.
  • If the constructor is defined using record syntax, the derived Read will parse only the record-syntax form, and furthermore, the fields must be given in the same order as the original declaration.
  • The derived Read instance allows arbitrary Haskell whitespace between tokens of the input string. Extra parentheses are also allowed.

For example, given the declarations

infixr 5 :^:
data Tree a =  Leaf a  |  Tree a :^: Tree a

the derived instance of Read in Haskell 2010 is equivalent to

instance (Read a) => Read (Tree a) where

        readsPrec d r =  readParen (d > app_prec)
                         (\r -> [(Leaf m,t) |
                                 ("Leaf",s) <- lex r,
                                 (m,t) <- readsPrec (app_prec+1) s]) r

                      ++ readParen (d > up_prec)
                         (\r -> [(u:^:v,w) |
                                 (u,s) <- readsPrec (up_prec+1) r,
                                 (":^:",t) <- lex s,
                                 (v,w) <- readsPrec (up_prec+1) t]) r

          where app_prec = 10
                up_prec = 5

Note that right-associativity of :^: is unused.

The derived instance in GHC is equivalent to

instance (Read a) => Read (Tree a) where

        readPrec = parens $ (prec app_prec $ do
                                 Ident "Leaf" <- lexP
                                 m <- step readPrec
                                 return (Leaf m))

                     +++ (prec up_prec $ do
                                 u <- step readPrec
                                 Symbol ":^:" <- lexP
                                 v <- step readPrec
                                 return (u :^: v))

          where app_prec = 10
                up_prec = 5

        readListPrec = readListPrecDefault

Why do both readsPrec and readPrec exist, and why does GHC opt to implement readPrec in derived Read instances instead of readsPrec? The reason is that readsPrec is based on the ReadS type, and although ReadS is mentioned in the Haskell 2010 Report, it is not a very efficient parser data structure.

readPrec, on the other hand, is based on a much more efficient ReadPrec datatype (a.k.a "new-style parsers"), but its definition relies on the use of the RankNTypes language extension. Therefore, readPrec (and its cousin, readListPrec) are marked as GHC-only. Nevertheless, it is recommended to use readPrec instead of readsPrec whenever possible for the efficiency improvements it brings.

As mentioned above, derived Read instances in GHC will implement readPrec instead of readsPrec. The default implementations of readsPrec (and its cousin, readList) will simply use readPrec under the hood. If you are writing a Read instance by hand, it is recommended to write it like so:

instance Read T where
  readPrec     = ...
  readListPrec = readListPrecDefault

Minimal complete definition

readsPrec | readPrec

Methods

readsPrec #

Arguments

:: Int

the operator precedence of the enclosing context (a number from 0 to 11). Function application has precedence 10.

-> ReadS a 

attempts to parse a value from the front of the string, returning a list of (parsed value, remaining string) pairs. If there is no successful parse, the returned list is empty.

Derived instances of Read and Show satisfy the following:

That is, readsPrec parses the string produced by showsPrec, and delivers the value that showsPrec started with.

readList :: ReadS [a] #

The method readList is provided to allow the programmer to give a specialised way of parsing lists of values. For example, this is used by the predefined Read instance of the Char type, where values of type String should be are expected to use double quotes, rather than square brackets.

readPrec :: ReadPrec a #

Proposed replacement for readsPrec using new-style parsers (GHC only).

readListPrec :: ReadPrec [a] #

Proposed replacement for readList using new-style parsers (GHC only). The default definition uses readList. Instances that define readPrec should also define readListPrec as readListPrecDefault.

Instances
Read Bool

Since: base-2.1

Instance details

Defined in GHC.Read

Read Char

Since: base-2.1

Instance details

Defined in GHC.Read

Read Double

Since: base-2.1

Instance details

Defined in GHC.Read

Read Float

Since: base-2.1

Instance details

Defined in GHC.Read

Read Int

Since: base-2.1

Instance details

Defined in GHC.Read

Read Int8

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int16

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int32

Since: base-2.1

Instance details

Defined in GHC.Int

Read Int64

Since: base-2.1

Instance details

Defined in GHC.Int

Read Integer

Since: base-2.1

Instance details

Defined in GHC.Read

Read Natural

Since: base-4.8.0.0

Instance details

Defined in GHC.Natural

Read Ordering

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word

Since: base-4.5.0.0

Instance details

Defined in GHC.Read

Read Word8

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word16

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word32

Since: base-2.1

Instance details

Defined in GHC.Read

Read Word64

Since: base-2.1

Instance details

Defined in GHC.Read

Read ()

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS () #

readList :: ReadS [()] #

readPrec :: ReadPrec () #

readListPrec :: ReadPrec [()] #

Read ByteString 
Instance details

Defined in Data.ByteString.Internal

Read ByteString 
Instance details

Defined in Data.ByteString.Lazy.Internal

Read Scientific

Supports the skipping of parentheses and whitespaces. Example:

> read " ( ((  -1.0e+3 ) ))" :: Scientific
-1000.0

(Note: This Read instance makes internal use of scientificP to parse the floating-point number.)

Instance details

Defined in Data.Scientific

Read Value 
Instance details

Defined in Data.Aeson.Types.Internal

Read DotNetTime 
Instance details

Defined in Data.Aeson.Types.Internal

Read Color 
Instance details

Defined in System.Console.ANSI.Types

Read ColorIntensity 
Instance details

Defined in System.Console.ANSI.Types

Read ConsoleLayer 
Instance details

Defined in System.Console.ANSI.Types

Read BlinkSpeed 
Instance details

Defined in System.Console.ANSI.Types

Read Underlining 
Instance details

Defined in System.Console.ANSI.Types

Read ConsoleIntensity 
Instance details

Defined in System.Console.ANSI.Types

Read SGR 
Instance details

Defined in System.Console.ANSI.Types

Read Void

Reading a Void value is always a parse error, considering Void as a data type with no constructors.

Since: base-4.8.0.0

Instance details

Defined in Data.Void

Read RTSStats 
Instance details

Defined in GHC.Stats

Read GCDetails 
Instance details

Defined in GHC.Stats

Read ByteOrder 
Instance details

Defined in GHC.ByteOrder

Read Version 
Instance details

Defined in Data.Version

Read CDev 
Instance details

Defined in System.Posix.Types

Read CIno 
Instance details

Defined in System.Posix.Types

Read CMode 
Instance details

Defined in System.Posix.Types

Read COff 
Instance details

Defined in System.Posix.Types

Read CPid 
Instance details

Defined in System.Posix.Types

Read CSsize 
Instance details

Defined in System.Posix.Types

Read CGid 
Instance details

Defined in System.Posix.Types

Read CNlink 
Instance details

Defined in System.Posix.Types

Read CUid 
Instance details

Defined in System.Posix.Types

Read CCc 
Instance details

Defined in System.Posix.Types

Read CSpeed 
Instance details

Defined in System.Posix.Types

Read CTcflag 
Instance details

Defined in System.Posix.Types

Read CRLim 
Instance details

Defined in System.Posix.Types

Read CBlkSize 
Instance details

Defined in System.Posix.Types

Read CBlkCnt 
Instance details

Defined in System.Posix.Types

Read CClockId 
Instance details

Defined in System.Posix.Types

Read CFsBlkCnt 
Instance details

Defined in System.Posix.Types

Read CFsFilCnt 
Instance details

Defined in System.Posix.Types

Read CId 
Instance details

Defined in System.Posix.Types

Read CKey 
Instance details

Defined in System.Posix.Types

Read Fd 
Instance details

Defined in System.Posix.Types

Read ExitCode 
Instance details

Defined in GHC.IO.Exception

Read BufferMode 
Instance details

Defined in GHC.IO.Handle.Types

Read Newline 
Instance details

Defined in GHC.IO.Handle.Types

Read NewlineMode 
Instance details

Defined in GHC.IO.Handle.Types

Read SeekMode 
Instance details

Defined in GHC.IO.Device

Read All 
Instance details

Defined in Data.Semigroup.Internal

Read Any 
Instance details

Defined in Data.Semigroup.Internal

Read Fixity 
Instance details

Defined in GHC.Generics

Read Associativity 
Instance details

Defined in GHC.Generics

Read SourceUnpackedness 
Instance details

Defined in GHC.Generics

Read SourceStrictness 
Instance details

Defined in GHC.Generics

Read DecidedStrictness 
Instance details

Defined in GHC.Generics

Read SomeSymbol

Since: base-4.7.0.0

Instance details

Defined in GHC.TypeLits

Read SomeNat

Since: base-4.7.0.0

Instance details

Defined in GHC.TypeNats

Read CChar 
Instance details

Defined in Foreign.C.Types

Read CSChar 
Instance details

Defined in Foreign.C.Types

Read CUChar 
Instance details

Defined in Foreign.C.Types

Read CShort 
Instance details

Defined in Foreign.C.Types

Read CUShort 
Instance details

Defined in Foreign.C.Types

Read CInt 
Instance details

Defined in Foreign.C.Types

Read CUInt 
Instance details

Defined in Foreign.C.Types

Read CLong 
Instance details

Defined in Foreign.C.Types

Read CULong 
Instance details

Defined in Foreign.C.Types

Read CLLong 
Instance details

Defined in Foreign.C.Types

Read CULLong 
Instance details

Defined in Foreign.C.Types

Read CBool 
Instance details

Defined in Foreign.C.Types

Read CFloat 
Instance details

Defined in Foreign.C.Types

Read CDouble 
Instance details

Defined in Foreign.C.Types

Read CPtrdiff 
Instance details

Defined in Foreign.C.Types

Read CSize 
Instance details

Defined in Foreign.C.Types

Read CWchar 
Instance details

Defined in Foreign.C.Types

Read CSigAtomic 
Instance details

Defined in Foreign.C.Types

Read CClock 
Instance details

Defined in Foreign.C.Types

Read CTime 
Instance details

Defined in Foreign.C.Types

Read CUSeconds 
Instance details

Defined in Foreign.C.Types

Read CSUSeconds 
Instance details

Defined in Foreign.C.Types

Read CIntPtr 
Instance details

Defined in Foreign.C.Types

Read CUIntPtr 
Instance details

Defined in Foreign.C.Types

Read CIntMax 
Instance details

Defined in Foreign.C.Types

Read CUIntMax 
Instance details

Defined in Foreign.C.Types

Read WordPtr 
Instance details

Defined in Foreign.Ptr

Read IntPtr 
Instance details

Defined in Foreign.Ptr

Read IOMode 
Instance details

Defined in GHC.IO.IOMode

Read Lexeme

Since: base-2.1

Instance details

Defined in GHC.Read

Read GeneralCategory 
Instance details

Defined in GHC.Read

Read ShortByteString 
Instance details

Defined in Data.ByteString.Short.Internal

Read IntSet 
Instance details

Defined in Data.IntSet.Internal

Read XdgDirectory 
Instance details

Defined in System.Directory

Read FileType 
Instance details

Defined in System.Directory.Internal.Common

Read Permissions 
Instance details

Defined in System.Directory.Internal.Common

Read Verbosity 
Instance details

Defined in Gauge.Main.Options

Read MatchType 
Instance details

Defined in Gauge.Main.Options

Read Mode 
Instance details

Defined in Gauge.Main.Options

Read DisplayMode 
Instance details

Defined in Gauge.Main.Options

Read Config 
Instance details

Defined in Gauge.Main.Options

Read DatatypeVariant 
Instance details

Defined in Language.Haskell.TH.Datatype

Read Half 
Instance details

Defined in Numeric.Half

Read Seed 
Instance details

Defined in Hedgehog.Internal.Seed

Read Size 
Instance details

Defined in Hedgehog.Internal.Range

Read Pos 
Instance details

Defined in Text.Megaparsec.Pos

Read SourcePos 
Instance details

Defined in Text.Megaparsec.Pos

Read IntMultiSet 
Instance details

Defined in Data.IntMultiSet

Read AddrInfoFlag 
Instance details

Defined in Network.Socket

Read NameInfoFlag 
Instance details

Defined in Network.Socket

Read SocketType 
Instance details

Defined in Network.Socket.Types

Read Family 
Instance details

Defined in Network.Socket.Types

Read PortNumber 
Instance details

Defined in Network.Socket.Types

Read Greediness 
Instance details

Defined in Text.Regex.Applicative.Types

Read FPFormat 
Instance details

Defined in Data.Text.Lazy.Builder.RealFloat

Read ShortText 
Instance details

Defined in Data.Text.Short.Internal

Read UUID 
Instance details

Defined in Data.UUID.Types.Internal

Read UnpackedUUID 
Instance details

Defined in Data.UUID.Types.Internal

Read Weight 
Instance details

Defined in Weigh

Read Direction 
Instance details

Defined in Data.Graph.Inductive.Query.MaxFlow2

Methods

readsPrec :: Int -> ReadS Direction #

readList :: ReadS [Direction] #

readPrec :: ReadPrec Direction #

readListPrec :: ReadPrec [Direction] #

Class () (Read a) 
Instance details

Defined in Data.Constraint

Methods

cls :: Read a :- () #

a :=> (Read (Dict a)) 
Instance details

Defined in Data.Constraint

Methods

ins :: a :- Read (Dict a) #

() :=> (Read Bool) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Bool #

() :=> (Read Char) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Char #

() :=> (Read Int) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Int #

() :=> (Read Natural) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Natural #

() :=> (Read Ordering) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Ordering #

() :=> (Read Word) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read Word #

() :=> (Read ()) 
Instance details

Defined in Data.Constraint

Methods

ins :: () :- Read () #

Read a => Read [a]

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS [a] #

readList :: ReadS [[a]] #

readPrec :: ReadPrec [a] #

readListPrec :: ReadPrec [[a]] #

Read a => Read (Maybe a)

Since: base-2.1

Instance details

Defined in GHC.Read

(Integral a, Read a) => Read (Ratio a)

Since: base-2.1

Instance details

Defined in GHC.Read

Read p => Read (Par1 p) 
Instance details

Defined in GHC.Generics

Read a => Read (Approximate a) 
Instance details

Defined in Data.Approximate.Type

Read a => Read (Complex a) 
Instance details

Defined in Data.Complex

HasResolution a => Read (Fixed a)

Since: base-4.3.0.0

Instance details

Defined in Data.Fixed

Read a => Read (Min a) 
Instance details

Defined in Data.Semigroup

Read a => Read (Max a) 
Instance details

Defined in Data.Semigroup

Read a => Read (First a) 
Instance details

Defined in Data.Semigroup

Read a => Read (Last a) 
Instance details

Defined in Data.Semigroup

Read m => Read (WrappedMonoid m) 
Instance details

Defined in Data.Semigroup

Read a => Read (Option a) 
Instance details

Defined in Data.Semigroup

Read a => Read (ZipList a) 
Instance details

Defined in Control.Applicative

Read a => Read (Identity a)

This instance would be equivalent to the derived instances of the Identity newtype if the runIdentity field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Identity

Read a => Read (First a) 
Instance details

Defined in Data.Monoid

Read a => Read (Last a) 
Instance details

Defined in Data.Monoid

Read a => Read (Dual a) 
Instance details

Defined in Data.Semigroup.Internal

Read a => Read (Sum a) 
Instance details

Defined in Data.Semigroup.Internal

Read a => Read (Product a) 
Instance details

Defined in Data.Semigroup.Internal

Read a => Read (Down a)

Since: base-4.7.0.0

Instance details

Defined in Data.Ord

Read a => Read (NonEmpty a) 
Instance details

Defined in GHC.Read

(Read s, FoldCase s) => Read (CI s) 
Instance details

Defined in Data.CaseInsensitive.Internal

a => Read (Dict a) 
Instance details

Defined in Data.Constraint

Read e => Read (IntMap e) 
Instance details

Defined in Data.IntMap.Internal

Read vertex => Read (SCC vertex)

Since: containers-0.5.9

Instance details

Defined in Data.Graph

Methods

readsPrec :: Int -> ReadS (SCC vertex) #

readList :: ReadS [SCC vertex] #

readPrec :: ReadPrec (SCC vertex) #

readListPrec :: ReadPrec [SCC vertex] #

Read a => Read (Tree a) 
Instance details

Defined in Data.Tree

Read a => Read (Seq a) 
Instance details

Defined in Data.Sequence.Internal

Read a => Read (ViewL a) 
Instance details

Defined in Data.Sequence.Internal

Read a => Read (ViewR a) 
Instance details

Defined in Data.Sequence.Internal

(Read a, Ord a) => Read (Set a) 
Instance details

Defined in Data.Set.Internal

Read a => Read (DList a) 
Instance details

Defined in Data.DList

(Ord a, Read a) => Read (Heap a) 
Instance details

Defined in Data.Heap

(Read a, Prim a) => Read (Vector a) 
Instance details

Defined in Data.Vector.Primitive

(Read a, Storable a) => Read (Vector a) 
Instance details

Defined in Data.Vector.Storable

(Eq a, Hashable a, Read a) => Read (HashSet a) 
Instance details

Defined in Data.HashSet

Read a => Read (Vector a) 
Instance details

Defined in Data.Vector

(Floating a, Read a) => Read (Log a) 
Instance details

Defined in Numeric.Log

Read t => Read (ErrorItem t) 
Instance details

Defined in Text.Megaparsec.Error

Read e => Read (ErrorFancy e) 
Instance details

Defined in Text.Megaparsec.Error

(Read a, Ord a) => Read (MultiSet a) 
Instance details

Defined in Data.MultiSet

Read a => Read (SmallArray a) 
Instance details

Defined in Data.Primitive.SmallArray

Read a => Read (Array a) 
Instance details

Defined in Data.Primitive.Array

Read a => Read (Bound a) 
Instance details

Defined in Data.Semilattice.Bound

Read a => Read (Order a) 
Instance details

Defined in Data.Semilattice.Order

Read a => Read (Meeting a) 
Instance details

Defined in Data.Semilattice.Meet

Read a => Read (GreaterThan a) 
Instance details

Defined in Data.Semilattice.Meet

Read a => Read (Joining a) 
Instance details

Defined in Data.Semilattice.Join

Read a => Read (LessThan a) 
Instance details

Defined in Data.Semilattice.Join

Read b => Read (GroupEdges b) 
Instance details

Defined in Data.Graph.Inductive.Graph

Methods

readsPrec :: Int -> ReadS (GroupEdges b) #

readList :: ReadS [GroupEdges b] #

readPrec :: ReadPrec (GroupEdges b) #

readListPrec :: ReadPrec [GroupEdges b] #

Read a => Read (FromListCounting a) 
Instance details

Defined in Data.Graph.Inductive.PatriciaTree

Methods

readsPrec :: Int -> ReadS (FromListCounting a) #

readList :: ReadS [FromListCounting a] #

readPrec :: ReadPrec (FromListCounting a) #

readListPrec :: ReadPrec [FromListCounting a] #

Read a => Read (DFSTree a) 
Instance details

Defined in Data.Graph.Inductive.Query.ArtPoint

Methods

readsPrec :: Int -> ReadS (DFSTree a) #

readList :: ReadS [DFSTree a] #

readPrec :: ReadPrec (DFSTree a) #

readListPrec :: ReadPrec [DFSTree a] #

Read a => Read (LOWTree a) 
Instance details

Defined in Data.Graph.Inductive.Query.ArtPoint

Methods

readsPrec :: Int -> ReadS (LOWTree a) #

readList :: ReadS [LOWTree a] #

readPrec :: ReadPrec (LOWTree a) #

readListPrec :: ReadPrec [LOWTree a] #

Read a => Read (Forest a) 
Instance details

Defined in Data.Heap

Methods

readsPrec :: Int -> ReadS (Forest a) #

readList :: ReadS [Forest a] #

readPrec :: ReadPrec (Forest a) #

readListPrec :: ReadPrec [Forest a] #

Read a => Read (Tree a) 
Instance details

Defined in Data.Heap

Methods

readsPrec :: Int -> ReadS (Tree a) #

readList :: ReadS [Tree a] #

readPrec :: ReadPrec (Tree a) #

readListPrec :: ReadPrec [Tree a] #

(Read a) :=> (Read (Complex a)) 
Instance details

Defined in Data.Constraint

Methods

ins :: Read a :- Read (Complex a) #

(Read a) :=> (Read [a]) 
Instance details

Defined in Data.Constraint

Methods

ins :: Read a :- Read [a] #

(Read a) :=> (Read (Maybe a)) 
Instance details

Defined in Data.Constraint

Methods

ins :: Read a :- Read (Maybe a) #

(Read a) :=> (Read (Identity a)) 
Instance details

Defined in Data.Constraint

Methods

ins :: Read a :- Read (Identity a) #

(Read a) :=> (Read (Const a b)) 
Instance details

Defined in Data.Constraint

Methods

ins :: Read a :- Read (Const a b) #

(Read a, Read b) => Read (Either a b) 
Instance details

Defined in Data.Either

Read (V1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

Read (U1 p)

Since: base-4.9.0.0

Instance details

Defined in GHC.Generics

(Read a, Read b) => Read (a, b)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b) #

readList :: ReadS [(a, b)] #

readPrec :: ReadPrec (a, b) #

readListPrec :: ReadPrec [(a, b)] #

(Read e, Read i) => Read (Report e i) 
Instance details

Defined in Text.Earley.Parser.Internal

(Eq k, Hashable k, Read k, Read e) => Read (HashMap k e) 
Instance details

Defined in Data.HashMap.Base

(Ord k, Read k, Read e) => Read (Map k e) 
Instance details

Defined in Data.Map.Internal

Methods

readsPrec :: Int -> ReadS (Map k e) #

readList :: ReadS [Map k e] #

readPrec :: ReadPrec (Map k e) #

readListPrec :: ReadPrec [Map k e] #

(Ix a, Read a, Read b) => Read (Array a b)

Since: base-2.1

Instance details

Defined in GHC.Read

(Read a, Read b) => Read (Arg a b) 
Instance details

Defined in Data.Semigroup

Methods

readsPrec :: Int -> ReadS (Arg a b) #

readList :: ReadS [Arg a b] #

readPrec :: ReadPrec (Arg a b) #

readListPrec :: ReadPrec [Arg a b] #

Read (Proxy t)

Since: base-4.7.0.0

Instance details

Defined in Data.Proxy

(Read1 m, Read a) => Read (MaybeT m a) 
Instance details

Defined in Control.Monad.Trans.Maybe

(Read a, Read b) => Read (Gr a b) 
Instance details

Defined in Data.Graph.Inductive.PatriciaTree

Methods

readsPrec :: Int -> ReadS (Gr a b) #

readList :: ReadS [Gr a b] #

readPrec :: ReadPrec (Gr a b) #

readListPrec :: ReadPrec [Gr a b] #

(Read a, Read b) => Read (Heap a b) 
Instance details

Defined in Data.Graph.Inductive.Internal.Heap

Methods

readsPrec :: Int -> ReadS (Heap a b) #

readList :: ReadS [Heap a b] #

readPrec :: ReadPrec (Heap a b) #

readListPrec :: ReadPrec [Heap a b] #

(Read1 f, Read a) => Read (Cofree f a) 
Instance details

Defined in Control.Comonad.Cofree

(Read1 f, Read a) => Read (Free f a) 
Instance details

Defined in Control.Monad.Free

Methods

readsPrec :: Int -> ReadS (Free f a) #

readList :: ReadS [Free f a] #

readPrec :: ReadPrec (Free f a) #

readListPrec :: ReadPrec [Free f a] #

(Read p, Read a) => Read (Entry p a) 
Instance details

Defined in Data.Heap

(Functor f, Read (f a)) => Read (Yoneda f a) 
Instance details

Defined in Data.Functor.Yoneda

(Read t, Read e, Ord t, Ord e) => Read (ParseError t e) 
Instance details

Defined in Text.Megaparsec.Error

(Integral a, Read a) :=> (Read (Ratio a)) 
Instance details

Defined in Data.Constraint

Methods

ins :: (Integral a, Read a) :- Read (Ratio a) #

(Read a, Read b) :=> (Read (a, b)) 
Instance details

Defined in Data.Constraint

Methods

ins :: (Read a, Read b) :- Read (a, b) #

(Read a, Read b) :=> (Read (Either a b)) 
Instance details

Defined in Data.Constraint

Methods

ins :: (Read a, Read b) :- Read (Either a b) #

Read (f p) => Read (Rec1 f p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (Rec1 f p) #

readList :: ReadS [Rec1 f p] #

readPrec :: ReadPrec (Rec1 f p) #

readListPrec :: ReadPrec [Rec1 f p] #

(Read a, Read b, Read c) => Read (a, b, c)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c) #

readList :: ReadS [(a, b, c)] #

readPrec :: ReadPrec (a, b, c) #

readListPrec :: ReadPrec [(a, b, c)] #

Read a => Read (Const a b)

This instance would be equivalent to the derived instances of the Const newtype if the runConst field were removed

Since: base-4.8.0.0

Instance details

Defined in Data.Functor.Const

Read (f a) => Read (Alt f a) 
Instance details

Defined in Data.Semigroup.Internal

Methods

readsPrec :: Int -> ReadS (Alt f a) #

readList :: ReadS [Alt f a] #

readPrec :: ReadPrec (Alt f a) #

readListPrec :: ReadPrec [Alt f a] #

Coercible a b => Read (Coercion a b)

Since: base-4.7.0.0

Instance details

Defined in Data.Type.Coercion

a ~ b => Read (a :~: b)

Since: base-4.7.0.0

Instance details

Defined in Data.Type.Equality

Methods

readsPrec :: Int -> ReadS (a :~: b) #

readList :: ReadS [a :~: b] #

readPrec :: ReadPrec (a :~: b) #

readListPrec :: ReadPrec [a :~: b] #

Read (p a a) => Read (Join p a) 
Instance details

Defined in Data.Bifunctor.Join

Methods

readsPrec :: Int -> ReadS (Join p a) #

readList :: ReadS [Join p a] #

readPrec :: ReadPrec (Join p a) #

readListPrec :: ReadPrec [Join p a] #

Read (p (Fix p a) a) => Read (Fix p a) 
Instance details

Defined in Data.Bifunctor.Fix

Methods

readsPrec :: Int -> ReadS (Fix p a) #

readList :: ReadS [Fix p a] #

readPrec :: ReadPrec (Fix p a) #

readListPrec :: ReadPrec [Fix p a] #

(Read1 f, Read a) => Read (IdentityT f a) 
Instance details

Defined in Control.Monad.Trans.Identity

(Read e, Read1 m, Read a) => Read (ExceptT e m a) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

readsPrec :: Int -> ReadS (ExceptT e m a) #

readList :: ReadS [ExceptT e m a] #

readPrec :: ReadPrec (ExceptT e m a) #

readListPrec :: ReadPrec [ExceptT e m a] #

Read (gr a b) => Read (OrdGr gr a b) 
Instance details

Defined in Data.Graph.Inductive.Graph

Methods

readsPrec :: Int -> ReadS (OrdGr gr a b) #

readList :: ReadS [OrdGr gr a b] #

readPrec :: ReadPrec (OrdGr gr a b) #

readListPrec :: ReadPrec [OrdGr gr a b] #

(Read a, Read (f b)) => Read (FreeF f a b) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

readsPrec :: Int -> ReadS (FreeF f a b) #

readList :: ReadS [FreeF f a b] #

readPrec :: ReadPrec (FreeF f a b) #

readListPrec :: ReadPrec [FreeF f a b] #

(Read1 f, Read1 m, Read a) => Read (FreeT f m a) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

readsPrec :: Int -> ReadS (FreeT f m a) #

readList :: ReadS [FreeT f m a] #

readPrec :: ReadPrec (FreeT f m a) #

readListPrec :: ReadPrec [FreeT f m a] #

(Read a, Read (f b)) => Read (CofreeF f a b) 
Instance details

Defined in Control.Comonad.Trans.Cofree

Methods

readsPrec :: Int -> ReadS (CofreeF f a b) #

readList :: ReadS [CofreeF f a b] #

readPrec :: ReadPrec (CofreeF f a b) #

readListPrec :: ReadPrec [CofreeF f a b] #

Read (w (CofreeF f a (CofreeT f w a))) => Read (CofreeT f w a) 
Instance details

Defined in Control.Comonad.Trans.Cofree

Methods

readsPrec :: Int -> ReadS (CofreeT f w a) #

readList :: ReadS [CofreeT f w a] #

readPrec :: ReadPrec (CofreeT f w a) #

readListPrec :: ReadPrec [CofreeT f w a] #

(Read e, Read1 m, Read a) => Read (ErrorT e m a) 
Instance details

Defined in Control.Monad.Trans.Error

Methods

readsPrec :: Int -> ReadS (ErrorT e m a) #

readList :: ReadS [ErrorT e m a] #

readPrec :: ReadPrec (ErrorT e m a) #

readListPrec :: ReadPrec [ErrorT e m a] #

(Read1 f, Read a) => Read (Backwards f a) 
Instance details

Defined in Control.Applicative.Backwards

Read b => Read (Tagged s b) 
Instance details

Defined in Data.Tagged

Read c => Read (K1 i c p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (K1 i c p) #

readList :: ReadS [K1 i c p] #

readPrec :: ReadPrec (K1 i c p) #

readListPrec :: ReadPrec [K1 i c p] #

(Read (f p), Read (g p)) => Read ((f :+: g) p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :+: g) p) #

readList :: ReadS [(f :+: g) p] #

readPrec :: ReadPrec ((f :+: g) p) #

readListPrec :: ReadPrec [(f :+: g) p] #

(Read (f p), Read (g p)) => Read ((f :*: g) p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :*: g) p) #

readList :: ReadS [(f :*: g) p] #

readPrec :: ReadPrec ((f :*: g) p) #

readListPrec :: ReadPrec [(f :*: g) p] #

(Read a, Read b, Read c, Read d) => Read (a, b, c, d)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d) #

readList :: ReadS [(a, b, c, d)] #

readPrec :: ReadPrec (a, b, c, d) #

readListPrec :: ReadPrec [(a, b, c, d)] #

(Read1 f, Read1 g, Read a) => Read (Product f g a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Product

Methods

readsPrec :: Int -> ReadS (Product f g a) #

readList :: ReadS [Product f g a] #

readPrec :: ReadPrec (Product f g a) #

readListPrec :: ReadPrec [Product f g a] #

(Read1 f, Read1 g, Read a) => Read (Sum f g a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Sum

Methods

readsPrec :: Int -> ReadS (Sum f g a) #

readList :: ReadS [Sum f g a] #

readPrec :: ReadPrec (Sum f g a) #

readListPrec :: ReadPrec [Sum f g a] #

a ~~ b => Read (a :~~: b)

Since: base-4.10.0.0

Instance details

Defined in Data.Type.Equality

Methods

readsPrec :: Int -> ReadS (a :~~: b) #

readList :: ReadS [a :~~: b] #

readPrec :: ReadPrec (a :~~: b) #

readListPrec :: ReadPrec [a :~~: b] #

Read (f p) => Read (M1 i c f p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS (M1 i c f p) #

readList :: ReadS [M1 i c f p] #

readPrec :: ReadPrec (M1 i c f p) #

readListPrec :: ReadPrec [M1 i c f p] #

Read (f (g p)) => Read ((f :.: g) p) 
Instance details

Defined in GHC.Generics

Methods

readsPrec :: Int -> ReadS ((f :.: g) p) #

readList :: ReadS [(f :.: g) p] #

readPrec :: ReadPrec ((f :.: g) p) #

readListPrec :: ReadPrec [(f :.: g) p] #

(Read a, Read b, Read c, Read d, Read e) => Read (a, b, c, d, e)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e) #

readList :: ReadS [(a, b, c, d, e)] #

readPrec :: ReadPrec (a, b, c, d, e) #

readListPrec :: ReadPrec [(a, b, c, d, e)] #

(Read1 f, Read1 g, Read a) => Read (Compose f g a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Compose

Methods

readsPrec :: Int -> ReadS (Compose f g a) #

readList :: ReadS [Compose f g a] #

readPrec :: ReadPrec (Compose f g a) #

readListPrec :: ReadPrec [Compose f g a] #

Read (p a b) => Read (WrappedBifunctor p a b) 
Instance details

Defined in Data.Bifunctor.Wrapped

Read (g b) => Read (Joker g a b) 
Instance details

Defined in Data.Bifunctor.Joker

Methods

readsPrec :: Int -> ReadS (Joker g a b) #

readList :: ReadS [Joker g a b] #

readPrec :: ReadPrec (Joker g a b) #

readListPrec :: ReadPrec [Joker g a b] #

Read (p b a) => Read (Flip p a b) 
Instance details

Defined in Data.Bifunctor.Flip

Methods

readsPrec :: Int -> ReadS (Flip p a b) #

readList :: ReadS [Flip p a b] #

readPrec :: ReadPrec (Flip p a b) #

readListPrec :: ReadPrec [Flip p a b] #

Read (f a) => Read (Clown f a b) 
Instance details

Defined in Data.Bifunctor.Clown

Methods

readsPrec :: Int -> ReadS (Clown f a b) #

readList :: ReadS [Clown f a b] #

readPrec :: ReadPrec (Clown f a b) #

readListPrec :: ReadPrec [Clown f a b] #

(Read a, Read b, Read c, Read d, Read e, Read f) => Read (a, b, c, d, e, f)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f) #

readList :: ReadS [(a, b, c, d, e, f)] #

readPrec :: ReadPrec (a, b, c, d, e, f) #

readListPrec :: ReadPrec [(a, b, c, d, e, f)] #

(Read (p a b), Read (q a b)) => Read (Sum p q a b) 
Instance details

Defined in Data.Bifunctor.Sum

Methods

readsPrec :: Int -> ReadS (Sum p q a b) #

readList :: ReadS [Sum p q a b] #

readPrec :: ReadPrec (Sum p q a b) #

readListPrec :: ReadPrec [Sum p q a b] #

(Read (f a b), Read (g a b)) => Read (Product f g a b) 
Instance details

Defined in Data.Bifunctor.Product

Methods

readsPrec :: Int -> ReadS (Product f g a b) #

readList :: ReadS [Product f g a b] #

readPrec :: ReadPrec (Product f g a b) #

readListPrec :: ReadPrec [Product f g a b] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g) => Read (a, b, c, d, e, f, g)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g) #

readList :: ReadS [(a, b, c, d, e, f, g)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g)] #

Read (f (p a b)) => Read (Tannen f p a b) 
Instance details

Defined in Data.Bifunctor.Tannen

Methods

readsPrec :: Int -> ReadS (Tannen f p a b) #

readList :: ReadS [Tannen f p a b] #

readPrec :: ReadPrec (Tannen f p a b) #

readListPrec :: ReadPrec [Tannen f p a b] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h) => Read (a, b, c, d, e, f, g, h)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h) #

readList :: ReadS [(a, b, c, d, e, f, g, h)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i) => Read (a, b, c, d, e, f, g, h, i)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i)] #

Read (p (f a) (g b)) => Read (Biff p f g a b) 
Instance details

Defined in Data.Bifunctor.Biff

Methods

readsPrec :: Int -> ReadS (Biff p f g a b) #

readList :: ReadS [Biff p f g a b] #

readPrec :: ReadPrec (Biff p f g a b) #

readListPrec :: ReadPrec [Biff p f g a b] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j) => Read (a, b, c, d, e, f, g, h, i, j)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k) => Read (a, b, c, d, e, f, g, h, i, j, k)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l) => Read (a, b, c, d, e, f, g, h, i, j, k, l)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m, Read n) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m, n)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m, n) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m, n)] #

(Read a, Read b, Read c, Read d, Read e, Read f, Read g, Read h, Read i, Read j, Read k, Read l, Read m, Read n, Read o) => Read (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)

Since: base-2.1

Instance details

Defined in GHC.Read

Methods

readsPrec :: Int -> ReadS (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

readList :: ReadS [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

readPrec :: ReadPrec (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) #

readListPrec :: ReadPrec [(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o)] #

type ReadS a = String -> [(a, String)] #

A parser for a type a, represented as a function that takes a String and returns a list of possible parses as (a,String) pairs.

Note that this kind of backtracking parser is very inefficient; reading a large structure may be quite slow (cf ReadP).

reads :: Read a => ReadS a #

equivalent to readsPrec with a precedence of 0.

readMaybe :: Read a => String -> Maybe a #

Parse a string using the Read instance. Succeeds if there is exactly one valid result.

>>> readMaybe "123" :: Maybe Int
Just 123
>>> readMaybe "hello" :: Maybe Int
Nothing

Since: base-4.6.0.0

readEither :: Read a => String -> Either String a #

Parse a string using the Read instance. Succeeds if there is exactly one valid result. A Left value indicates a parse error.

>>> readEither "123" :: Either String Int
Right 123
>>> readEither "hello" :: Either String Int
Left "Prelude.read: no parse"

Since: base-4.6.0.0

readParen :: Bool -> ReadS a -> ReadS a #

readParen True p parses what p parses, but surrounded with parentheses.

readParen False p parses what p parses, but optionally surrounded with parentheses.

readsData :: (String -> ReadS a) -> Int -> ReadS a #

readsData p d is a parser for datatypes where each alternative begins with a data constructor. It parses the constructor and passes it to p. Parsers for various constructors can be constructed with readsUnary, readsUnary1 and readsBinary1, and combined with mappend from the Monoid class.

Since: base-4.9.0.0

readData :: ReadPrec a -> ReadPrec a #

readData p is a parser for datatypes where each alternative begins with a data constructor. It parses the constructor and passes it to p. Parsers for various constructors can be constructed with readUnaryWith and readBinaryWith, and combined with '(|)' from the Alternative class.

Since: base-4.10.0.0

readsUnaryWith :: (Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t #

readsUnaryWith rp n c n' matches the name of a unary data constructor and then parses its argument using rp.

Since: base-4.9.0.0

readUnaryWith :: ReadPrec a -> String -> (a -> t) -> ReadPrec t #

readUnaryWith rp n c' matches the name of a unary data constructor and then parses its argument using rp.

Since: base-4.10.0.0

readsBinaryWith :: (Int -> ReadS a) -> (Int -> ReadS b) -> String -> (a -> b -> t) -> String -> ReadS t #

readsBinaryWith rp1 rp2 n c n' matches the name of a binary data constructor and then parses its arguments using rp1 and rp2 respectively.

Since: base-4.9.0.0

readBinaryWith :: ReadPrec a -> ReadPrec b -> String -> (a -> b -> t) -> ReadPrec t #

readBinaryWith rp1 rp2 n c' matches the name of a binary data constructor and then parses its arguments using rp1 and rp2 respectively.

Since: base-4.10.0.0

class Read1 (f :: * -> *) where #

Lifting of the Read class to unary type constructors.

Both liftReadsPrec and liftReadPrec exist to match the interface provided in the Read type class, but it is recommended to implement Read1 instances using liftReadPrec as opposed to liftReadsPrec, since the former is more efficient than the latter. For example:

instance Read1 T where
  liftReadPrec     = ...
  liftReadListPrec = liftReadListPrecDefault

For more information, refer to the documentation for the Read class.

Since: base-4.9.0.0

Minimal complete definition

liftReadsPrec | liftReadPrec

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a) #

readsPrec function for an application of the type constructor based on readsPrec and readList functions for the argument type.

Since: base-4.9.0.0

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [f a] #

readList function for an application of the type constructor based on readsPrec and readList functions for the argument type. The default implementation using standard list syntax is correct for most types.

Since: base-4.9.0.0

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (f a) #

readPrec function for an application of the type constructor based on readPrec and readListPrec functions for the argument type.

Since: base-4.10.0.0

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [f a] #

readListPrec function for an application of the type constructor based on readPrec and readListPrec functions for the argument type.

The default definition uses liftReadList. Instances that define liftReadPrec should also define liftReadListPrec as liftReadListPrecDefault.

Since: base-4.10.0.0

Instances
Read1 []

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS [a] #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [[a]] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [a] #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [[a]] #

Read1 Maybe

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Maybe a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Maybe a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Maybe a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Maybe a] #

Read1 Identity

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Identity a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Identity a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Identity a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Identity a] #

Read1 NonEmpty

Since: base-4.10.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (NonEmpty a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [NonEmpty a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (NonEmpty a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [NonEmpty a] #

Read1 IntMap

Since: containers-0.5.9

Instance details

Defined in Data.IntMap.Internal

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (IntMap a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [IntMap a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (IntMap a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [IntMap a] #

Read1 SCC

Since: containers-0.5.9

Instance details

Defined in Data.Graph

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (SCC a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [SCC a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (SCC a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [SCC a] #

Read1 Tree

Since: containers-0.5.9

Instance details

Defined in Data.Tree

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Tree a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Tree a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Tree a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Tree a] #

Read1 Seq

Since: containers-0.5.9

Instance details

Defined in Data.Sequence.Internal

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Seq a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Seq a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Seq a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Seq a] #

Read1 Vector 
Instance details

Defined in Data.Vector

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Vector a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Vector a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Vector a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Vector a] #

Read1 SmallArray

Since: primitive-0.6.4.0

Instance details

Defined in Data.Primitive.SmallArray

Read1 Array

Since: primitive-0.6.4.0

Instance details

Defined in Data.Primitive.Array

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Array a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Array a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Array a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Array a] #

Read a => Read1 (Either a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (Either a a0) #

liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [Either a a0] #

liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (Either a a0) #

liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [Either a a0] #

Read a => Read1 ((,) a)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (a, a0) #

liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [(a, a0)] #

liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (a, a0) #

liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [(a, a0)] #

(Eq k, Hashable k, Read k) => Read1 (HashMap k) 
Instance details

Defined in Data.HashMap.Base

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (HashMap k a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [HashMap k a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (HashMap k a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [HashMap k a] #

(Ord k, Read k) => Read1 (Map k)

Since: containers-0.5.9

Instance details

Defined in Data.Map.Internal

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Map k a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Map k a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Map k a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Map k a] #

Read1 (Proxy :: * -> *)

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] #

Read1 m => Read1 (MaybeT m) 
Instance details

Defined in Control.Monad.Trans.Maybe

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (MaybeT m a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [MaybeT m a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (MaybeT m a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [MaybeT m a] #

Read1 f => Read1 (Cofree f) 
Instance details

Defined in Control.Comonad.Cofree

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Cofree f a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Cofree f a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Cofree f a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Cofree f a] #

Read1 f => Read1 (Free f) 
Instance details

Defined in Control.Monad.Free

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Free f a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Free f a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Free f a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Free f a] #

(Read1 f, Functor f) => Read1 (Yoneda f) 
Instance details

Defined in Data.Functor.Yoneda

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Yoneda f a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Yoneda f a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Yoneda f a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Yoneda f a] #

Read a => Read1 (Const a :: * -> *)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (Const a a0) #

liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [Const a a0] #

liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (Const a a0) #

liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [Const a a0] #

Read1 f => Read1 (IdentityT f) 
Instance details

Defined in Control.Monad.Trans.Identity

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (IdentityT f a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [IdentityT f a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (IdentityT f a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [IdentityT f a] #

(Read e, Read1 m) => Read1 (ExceptT e m) 
Instance details

Defined in Control.Monad.Trans.Except

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ExceptT e m a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [ExceptT e m a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (ExceptT e m a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ExceptT e m a] #

(Read1 f, Read a) => Read1 (FreeF f a) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

liftReadsPrec :: (Int -> ReadS a0) -> ReadS [a0] -> Int -> ReadS (FreeF f a a0) #

liftReadList :: (Int -> ReadS a0) -> ReadS [a0] -> ReadS [FreeF f a a0] #

liftReadPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec (FreeF f a a0) #

liftReadListPrec :: ReadPrec a0 -> ReadPrec [a0] -> ReadPrec [FreeF f a a0] #

(Read1 f, Read1 m) => Read1 (FreeT f m) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (FreeT f m a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [FreeT f m a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (FreeT f m a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [FreeT f m a] #

(Read e, Read1 m) => Read1 (ErrorT e m) 
Instance details

Defined in Control.Monad.Trans.Error

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ErrorT e m a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [ErrorT e m a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (ErrorT e m a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [ErrorT e m a] #

Read1 f => Read1 (Backwards f) 
Instance details

Defined in Control.Applicative.Backwards

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Backwards f a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Backwards f a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Backwards f a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Backwards f a] #

Read1 (Tagged s) 
Instance details

Defined in Data.Tagged

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Tagged s a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Tagged s a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Tagged s a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Tagged s a] #

(Read1 f, Read1 g) => Read1 (Product f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Product

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Product f g a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Product f g a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Product f g a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Product f g a] #

(Read1 f, Read1 g) => Read1 (Sum f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Sum

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Sum f g a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Sum f g a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Sum f g a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Sum f g a] #

(Read1 f, Read1 g) => Read1 (Compose f g)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Compose

Methods

liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Compose f g a) #

liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Compose f g a] #

liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Compose f g a) #

liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Compose f g a] #

readsPrec1 :: (Read1 f, Read a) => Int -> ReadS (f a) #

Lift the standard readsPrec and readList functions through the type constructor.

Since: base-4.9.0.0

readPrec1 :: (Read1 f, Read a) => ReadPrec (f a) #

Lift the standard readPrec and readListPrec functions through the type constructor.

Since: base-4.10.0.0

liftReadListDefault :: Read1 f => (Int -> ReadS a) -> ReadS [a] -> ReadS [f a] #

A possible replacement definition for the liftReadList method. This is only needed for Read1 instances where liftReadListPrec isn't defined as liftReadListPrecDefault.

Since: base-4.10.0.0

liftReadListPrecDefault :: Read1 f => ReadPrec a -> ReadPrec [a] -> ReadPrec [f a] #

A possible replacement definition for the liftReadListPrec method, defined using liftReadPrec.

Since: base-4.10.0.0

class Read2 (f :: * -> * -> *) where #

Lifting of the Read class to binary type constructors.

Both liftReadsPrec2 and liftReadPrec2 exist to match the interface provided in the Read type class, but it is recommended to implement Read2 instances using liftReadPrec2 as opposed to liftReadsPrec2, since the former is more efficient than the latter. For example:

instance Read2 T where
  liftReadPrec2     = ...
  liftReadListPrec2 = liftReadListPrec2Default

For more information, refer to the documentation for the Read class. @since 4.9.0.0

Minimal complete definition

liftReadsPrec2 | liftReadPrec2

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (f a b) #

readsPrec function for an application of the type constructor based on readsPrec and readList functions for the argument types.

Since: base-4.9.0.0

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [f a b] #

readList function for an application of the type constructor based on readsPrec and readList functions for the argument types. The default implementation using standard list syntax is correct for most types.

Since: base-4.9.0.0

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (f a b) #

readPrec function for an application of the type constructor based on readPrec and readListPrec functions for the argument types.

Since: base-4.10.0.0

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [f a b] #

readListPrec function for an application of the type constructor based on readPrec and readListPrec functions for the argument types.

The default definition uses liftReadList2. Instances that define liftReadPrec2 should also define liftReadListPrec2 as liftReadListPrec2Default.

Since: base-4.10.0.0

Instances
Read2 Either

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Either a b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Either a b] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Either a b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Either a b] #

Read2 (,)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (a, b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [(a, b)] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (a, b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [(a, b)] #

Read2 (Const :: * -> * -> *)

Since: base-4.9.0.0

Instance details

Defined in Data.Functor.Classes

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Const a b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Const a b] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Const a b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Const a b] #

Read1 f => Read2 (FreeF f) 
Instance details

Defined in Control.Monad.Trans.Free

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (FreeF f a b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [FreeF f a b] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (FreeF f a b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [FreeF f a b] #

Read2 (Tagged :: * -> * -> *) 
Instance details

Defined in Data.Tagged

Methods

liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Tagged a b) #

liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Tagged a b] #

liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Tagged a b) #

liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Tagged a b] #

readsPrec2 :: (Read2 f, Read a, Read b) => Int -> ReadS (f a b) #

Lift the standard readsPrec function through the type constructor.

Since: base-4.9.0.0

readPrec2 :: (Read2 f, Read a, Read b) => ReadPrec (f a b) #

Lift the standard readPrec function through the type constructor.

Since: base-4.10.0.0

liftReadList2Default :: Read2 f => (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [f a b] #

A possible replacement definition for the liftReadList2 method. This is only needed for Read2 instances where liftReadListPrec2 isn't defined as liftReadListPrec2Default.

Since: base-4.10.0.0

liftReadListPrec2Default :: Read2 f => ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [f a b] #

A possible replacement definition for the liftReadListPrec2 method, defined using liftReadPrec2.

Since: base-4.10.0.0