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Diffstat (limited to 'third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Classes.hs')
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diff --git a/third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Classes.hs b/third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Classes.hs new file mode 100644 index 0000000000..bda1749643 --- /dev/null +++ b/third_party/bazel/rules_haskell/examples/transformers/legacy/pre711/Data/Functor/Classes.hs @@ -0,0 +1,529 @@ +{-# LANGUAGE CPP #-} +#if __GLASGOW_HASKELL__ >= 702 +{-# LANGUAGE Safe #-} +#endif +#if __GLASGOW_HASKELL__ >= 708 +{-# LANGUAGE DeriveDataTypeable #-} +{-# LANGUAGE StandaloneDeriving #-} +#endif +----------------------------------------------------------------------------- +-- | +-- Module : Data.Functor.Classes +-- Copyright : (c) Ross Paterson 2013 +-- License : BSD-style (see the file LICENSE) +-- +-- Maintainer : R.Paterson@city.ac.uk +-- Stability : experimental +-- Portability : portable +-- +-- Liftings of the Prelude classes 'Eq', 'Ord', 'Read' and 'Show' to +-- unary and binary type constructors. +-- +-- These classes are needed to express the constraints on arguments of +-- transformers in portable Haskell. Thus for a new transformer @T@, +-- one might write instances like +-- +-- > instance (Eq1 f) => Eq1 (T f) where ... +-- > instance (Ord1 f) => Ord1 (T f) where ... +-- > instance (Read1 f) => Read1 (T f) where ... +-- > instance (Show1 f) => Show1 (T f) where ... +-- +-- If these instances can be defined, defining instances of the base +-- classes is mechanical: +-- +-- > instance (Eq1 f, Eq a) => Eq (T f a) where (==) = eq1 +-- > instance (Ord1 f, Ord a) => Ord (T f a) where compare = compare1 +-- > instance (Read1 f, Read a) => Read (T f a) where readsPrec = readsPrec1 +-- > instance (Show1 f, Show a) => Show (T f a) where showsPrec = showsPrec1 +-- +----------------------------------------------------------------------------- + +module Data.Functor.Classes ( + -- * Liftings of Prelude classes + -- ** For unary constructors + Eq1(..), eq1, + Ord1(..), compare1, + Read1(..), readsPrec1, + Show1(..), showsPrec1, + -- ** For binary constructors + Eq2(..), eq2, + Ord2(..), compare2, + Read2(..), readsPrec2, + Show2(..), showsPrec2, + -- * Helper functions + -- $example + readsData, + readsUnaryWith, + readsBinaryWith, + showsUnaryWith, + showsBinaryWith, + -- ** Obsolete helpers + readsUnary, + readsUnary1, + readsBinary1, + showsUnary, + showsUnary1, + showsBinary1, + ) where + +import Control.Applicative (Const(Const)) +import Data.Functor.Identity (Identity(Identity)) +import Data.Monoid (mappend) +#if MIN_VERSION_base(4,7,0) +import Data.Proxy (Proxy(Proxy)) +#endif +#if __GLASGOW_HASKELL__ >= 708 +import Data.Typeable +#endif +import Text.Show (showListWith) + +-- | Lifting of the 'Eq' class to unary type constructors. +class Eq1 f where + -- | Lift an equality test through the type constructor. + -- + -- The function will usually be applied to an equality function, + -- but the more general type ensures that the implementation uses + -- it to compare elements of the first container with elements of + -- the second. + liftEq :: (a -> b -> Bool) -> f a -> f b -> Bool + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Eq1 +#endif + +-- | Lift the standard @('==')@ function through the type constructor. +eq1 :: (Eq1 f, Eq a) => f a -> f a -> Bool +eq1 = liftEq (==) + +-- | Lifting of the 'Ord' class to unary type constructors. +class (Eq1 f) => Ord1 f where + -- | Lift a 'compare' function through the type constructor. + -- + -- The function will usually be applied to a comparison function, + -- but the more general type ensures that the implementation uses + -- it to compare elements of the first container with elements of + -- the second. + liftCompare :: (a -> b -> Ordering) -> f a -> f b -> Ordering + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Ord1 +#endif + +-- | Lift the standard 'compare' function through the type constructor. +compare1 :: (Ord1 f, Ord a) => f a -> f a -> Ordering +compare1 = liftCompare compare + +-- | Lifting of the 'Read' class to unary type constructors. +class Read1 f where + -- | 'readsPrec' function for an application of the type constructor + -- based on 'readsPrec' and 'readList' functions for the argument type. + liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> 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. + liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [f a] + liftReadList rp rl = readListWith (liftReadsPrec rp rl 0) + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Read1 +#endif + +-- | Read a list (using square brackets and commas), given a function +-- for reading elements. +readListWith :: ReadS a -> ReadS [a] +readListWith rp = + readParen False (\r -> [pr | ("[",s) <- lex r, pr <- readl s]) + where + readl s = [([],t) | ("]",t) <- lex s] ++ + [(x:xs,u) | (x,t) <- rp s, (xs,u) <- readl' t] + readl' s = [([],t) | ("]",t) <- lex s] ++ + [(x:xs,v) | (",",t) <- lex s, (x,u) <- rp t, (xs,v) <- readl' u] + +-- | Lift the standard 'readsPrec' and 'readList' functions through the +-- type constructor. +readsPrec1 :: (Read1 f, Read a) => Int -> ReadS (f a) +readsPrec1 = liftReadsPrec readsPrec readList + +-- | Lifting of the 'Show' class to unary type constructors. +class Show1 f where + -- | 'showsPrec' function for an application of the type constructor + -- based on 'showsPrec' and 'showList' functions for the argument type. + liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> + Int -> f a -> ShowS + + -- | 'showList' function for an application of the type constructor + -- based on 'showsPrec' and 'showList' functions for the argument type. + -- The default implementation using standard list syntax is correct + -- for most types. + liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> + [f a] -> ShowS + liftShowList sp sl = showListWith (liftShowsPrec sp sl 0) + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Show1 +#endif + +-- | Lift the standard 'showsPrec' and 'showList' functions through the +-- type constructor. +showsPrec1 :: (Show1 f, Show a) => Int -> f a -> ShowS +showsPrec1 = liftShowsPrec showsPrec showList + +-- | Lifting of the 'Eq' class to binary type constructors. +class Eq2 f where + -- | Lift equality tests through the type constructor. + -- + -- The function will usually be applied to equality functions, + -- but the more general type ensures that the implementation uses + -- them to compare elements of the first container with elements of + -- the second. + liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> f a c -> f b d -> Bool + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Eq2 +#endif + +-- | Lift the standard @('==')@ function through the type constructor. +eq2 :: (Eq2 f, Eq a, Eq b) => f a b -> f a b -> Bool +eq2 = liftEq2 (==) (==) + +-- | Lifting of the 'Ord' class to binary type constructors. +class (Eq2 f) => Ord2 f where + -- | Lift 'compare' functions through the type constructor. + -- + -- The function will usually be applied to comparison functions, + -- but the more general type ensures that the implementation uses + -- them to compare elements of the first container with elements of + -- the second. + liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> + f a c -> f b d -> Ordering + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Ord2 +#endif + +-- | Lift the standard 'compare' function through the type constructor. +compare2 :: (Ord2 f, Ord a, Ord b) => f a b -> f a b -> Ordering +compare2 = liftCompare2 compare compare + +-- | Lifting of the 'Read' class to binary type constructors. +class Read2 f where + -- | 'readsPrec' function for an application of the type constructor + -- based on 'readsPrec' and 'readList' functions for the argument types. + liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> + (Int -> ReadS b) -> ReadS [b] -> Int -> 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. + liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> + (Int -> ReadS b) -> ReadS [b] -> ReadS [f a b] + liftReadList2 rp1 rl1 rp2 rl2 = + readListWith (liftReadsPrec2 rp1 rl1 rp2 rl2 0) + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Read2 +#endif + +-- | Lift the standard 'readsPrec' function through the type constructor. +readsPrec2 :: (Read2 f, Read a, Read b) => Int -> ReadS (f a b) +readsPrec2 = liftReadsPrec2 readsPrec readList readsPrec readList + +-- | Lifting of the 'Show' class to binary type constructors. +class Show2 f where + -- | 'showsPrec' function for an application of the type constructor + -- based on 'showsPrec' and 'showList' functions for the argument types. + liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> + (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> f a b -> ShowS + + -- | 'showList' function for an application of the type constructor + -- based on 'showsPrec' and 'showList' functions for the argument types. + -- The default implementation using standard list syntax is correct + -- for most types. + liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> + (Int -> b -> ShowS) -> ([b] -> ShowS) -> [f a b] -> ShowS + liftShowList2 sp1 sl1 sp2 sl2 = + showListWith (liftShowsPrec2 sp1 sl1 sp2 sl2 0) + +#if __GLASGOW_HASKELL__ >= 708 +deriving instance Typeable Show2 +#endif + +-- | Lift the standard 'showsPrec' function through the type constructor. +showsPrec2 :: (Show2 f, Show a, Show b) => Int -> f a b -> ShowS +showsPrec2 = liftShowsPrec2 showsPrec showList showsPrec showList + +-- Instances for Prelude type constructors + +instance Eq1 Maybe where + liftEq _ Nothing Nothing = True + liftEq _ Nothing (Just _) = False + liftEq _ (Just _) Nothing = False + liftEq eq (Just x) (Just y) = eq x y + +instance Ord1 Maybe where + liftCompare _ Nothing Nothing = EQ + liftCompare _ Nothing (Just _) = LT + liftCompare _ (Just _) Nothing = GT + liftCompare comp (Just x) (Just y) = comp x y + +instance Read1 Maybe where + liftReadsPrec rp _ d = + readParen False (\ r -> [(Nothing,s) | ("Nothing",s) <- lex r]) + `mappend` + readsData (readsUnaryWith rp "Just" Just) d + +instance Show1 Maybe where + liftShowsPrec _ _ _ Nothing = showString "Nothing" + liftShowsPrec sp _ d (Just x) = showsUnaryWith sp "Just" d x + +instance Eq1 [] where + liftEq _ [] [] = True + liftEq _ [] (_:_) = False + liftEq _ (_:_) [] = False + liftEq eq (x:xs) (y:ys) = eq x y && liftEq eq xs ys + +instance Ord1 [] where + liftCompare _ [] [] = EQ + liftCompare _ [] (_:_) = LT + liftCompare _ (_:_) [] = GT + liftCompare comp (x:xs) (y:ys) = comp x y `mappend` liftCompare comp xs ys + +instance Read1 [] where + liftReadsPrec _ rl _ = rl + +instance Show1 [] where + liftShowsPrec _ sl _ = sl + +instance Eq2 (,) where + liftEq2 e1 e2 (x1, y1) (x2, y2) = e1 x1 x2 && e2 y1 y2 + +instance Ord2 (,) where + liftCompare2 comp1 comp2 (x1, y1) (x2, y2) = + comp1 x1 x2 `mappend` comp2 y1 y2 + +instance Read2 (,) where + liftReadsPrec2 rp1 _ rp2 _ _ = readParen False $ \ r -> + [((x,y), w) | ("(",s) <- lex r, + (x,t) <- rp1 0 s, + (",",u) <- lex t, + (y,v) <- rp2 0 u, + (")",w) <- lex v] + +instance Show2 (,) where + liftShowsPrec2 sp1 _ sp2 _ _ (x, y) = + showChar '(' . sp1 0 x . showChar ',' . sp2 0 y . showChar ')' + +instance (Eq a) => Eq1 ((,) a) where + liftEq = liftEq2 (==) + +instance (Ord a) => Ord1 ((,) a) where + liftCompare = liftCompare2 compare + +instance (Read a) => Read1 ((,) a) where + liftReadsPrec = liftReadsPrec2 readsPrec readList + +instance (Show a) => Show1 ((,) a) where + liftShowsPrec = liftShowsPrec2 showsPrec showList + +instance Eq2 Either where + liftEq2 e1 _ (Left x) (Left y) = e1 x y + liftEq2 _ _ (Left _) (Right _) = False + liftEq2 _ _ (Right _) (Left _) = False + liftEq2 _ e2 (Right x) (Right y) = e2 x y + +instance Ord2 Either where + liftCompare2 comp1 _ (Left x) (Left y) = comp1 x y + liftCompare2 _ _ (Left _) (Right _) = LT + liftCompare2 _ _ (Right _) (Left _) = GT + liftCompare2 _ comp2 (Right x) (Right y) = comp2 x y + +instance Read2 Either where + liftReadsPrec2 rp1 _ rp2 _ = readsData $ + readsUnaryWith rp1 "Left" Left `mappend` + readsUnaryWith rp2 "Right" Right + +instance Show2 Either where + liftShowsPrec2 sp1 _ _ _ d (Left x) = showsUnaryWith sp1 "Left" d x + liftShowsPrec2 _ _ sp2 _ d (Right x) = showsUnaryWith sp2 "Right" d x + +instance (Eq a) => Eq1 (Either a) where + liftEq = liftEq2 (==) + +instance (Ord a) => Ord1 (Either a) where + liftCompare = liftCompare2 compare + +instance (Read a) => Read1 (Either a) where + liftReadsPrec = liftReadsPrec2 readsPrec readList + +instance (Show a) => Show1 (Either a) where + liftShowsPrec = liftShowsPrec2 showsPrec showList + +#if MIN_VERSION_base(4,7,0) +instance Eq1 Proxy where + liftEq _ _ _ = True + +instance Ord1 Proxy where + liftCompare _ _ _ = EQ + +instance Show1 Proxy where + liftShowsPrec _ _ _ _ = showString "Proxy" + +instance Read1 Proxy where + liftReadsPrec _ _ d = + readParen (d > 10) (\r -> [(Proxy, s) | ("Proxy",s) <- lex r ]) +#endif + +-- Instances for other functors defined in the base package + +instance Eq1 Identity where + liftEq eq (Identity x) (Identity y) = eq x y + +instance Ord1 Identity where + liftCompare comp (Identity x) (Identity y) = comp x y + +instance Read1 Identity where + liftReadsPrec rp _ = readsData $ + readsUnaryWith rp "Identity" Identity + +instance Show1 Identity where + liftShowsPrec sp _ d (Identity x) = showsUnaryWith sp "Identity" d x + +instance Eq2 Const where + liftEq2 eq _ (Const x) (Const y) = eq x y + +instance Ord2 Const where + liftCompare2 comp _ (Const x) (Const y) = comp x y + +instance Read2 Const where + liftReadsPrec2 rp _ _ _ = readsData $ + readsUnaryWith rp "Const" Const + +instance Show2 Const where + liftShowsPrec2 sp _ _ _ d (Const x) = showsUnaryWith sp "Const" d x + +instance (Eq a) => Eq1 (Const a) where + liftEq = liftEq2 (==) +instance (Ord a) => Ord1 (Const a) where + liftCompare = liftCompare2 compare +instance (Read a) => Read1 (Const a) where + liftReadsPrec = liftReadsPrec2 readsPrec readList +instance (Show a) => Show1 (Const a) where + liftShowsPrec = liftShowsPrec2 showsPrec showList + +-- Building blocks + +-- | @'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. +readsData :: (String -> ReadS a) -> Int -> ReadS a +readsData reader d = + readParen (d > 10) $ \ r -> [res | (kw,s) <- lex r, res <- reader kw s] + +-- | @'readsUnaryWith' rp n c n'@ matches the name of a unary data constructor +-- and then parses its argument using @rp@. +readsUnaryWith :: (Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t +readsUnaryWith rp name cons kw s = + [(cons x,t) | kw == name, (x,t) <- rp 11 s] + +-- | @'readsBinaryWith' rp1 rp2 n c n'@ matches the name of a binary +-- data constructor and then parses its arguments using @rp1@ and @rp2@ +-- respectively. +readsBinaryWith :: (Int -> ReadS a) -> (Int -> ReadS b) -> + String -> (a -> b -> t) -> String -> ReadS t +readsBinaryWith rp1 rp2 name cons kw s = + [(cons x y,u) | kw == name, (x,t) <- rp1 11 s, (y,u) <- rp2 11 t] + +-- | @'showsUnaryWith' sp n d x@ produces the string representation of a +-- unary data constructor with name @n@ and argument @x@, in precedence +-- context @d@. +showsUnaryWith :: (Int -> a -> ShowS) -> String -> Int -> a -> ShowS +showsUnaryWith sp name d x = showParen (d > 10) $ + showString name . showChar ' ' . sp 11 x + +-- | @'showsBinaryWith' sp1 sp2 n d x y@ produces the string +-- representation of a binary data constructor with name @n@ and arguments +-- @x@ and @y@, in precedence context @d@. +showsBinaryWith :: (Int -> a -> ShowS) -> (Int -> b -> ShowS) -> + String -> Int -> a -> b -> ShowS +showsBinaryWith sp1 sp2 name d x y = showParen (d > 10) $ + showString name . showChar ' ' . sp1 11 x . showChar ' ' . sp2 11 y + +-- Obsolete building blocks + +-- | @'readsUnary' n c n'@ matches the name of a unary data constructor +-- and then parses its argument using 'readsPrec'. +{-# DEPRECATED readsUnary "Use readsUnaryWith to define liftReadsPrec" #-} +readsUnary :: (Read a) => String -> (a -> t) -> String -> ReadS t +readsUnary name cons kw s = + [(cons x,t) | kw == name, (x,t) <- readsPrec 11 s] + +-- | @'readsUnary1' n c n'@ matches the name of a unary data constructor +-- and then parses its argument using 'readsPrec1'. +{-# DEPRECATED readsUnary1 "Use readsUnaryWith to define liftReadsPrec" #-} +readsUnary1 :: (Read1 f, Read a) => String -> (f a -> t) -> String -> ReadS t +readsUnary1 name cons kw s = + [(cons x,t) | kw == name, (x,t) <- readsPrec1 11 s] + +-- | @'readsBinary1' n c n'@ matches the name of a binary data constructor +-- and then parses its arguments using 'readsPrec1'. +{-# DEPRECATED readsBinary1 "Use readsBinaryWith to define liftReadsPrec" #-} +readsBinary1 :: (Read1 f, Read1 g, Read a) => + String -> (f a -> g a -> t) -> String -> ReadS t +readsBinary1 name cons kw s = + [(cons x y,u) | kw == name, + (x,t) <- readsPrec1 11 s, (y,u) <- readsPrec1 11 t] + +-- | @'showsUnary' n d x@ produces the string representation of a unary data +-- constructor with name @n@ and argument @x@, in precedence context @d@. +{-# DEPRECATED showsUnary "Use showsUnaryWith to define liftShowsPrec" #-} +showsUnary :: (Show a) => String -> Int -> a -> ShowS +showsUnary name d x = showParen (d > 10) $ + showString name . showChar ' ' . showsPrec 11 x + +-- | @'showsUnary1' n d x@ produces the string representation of a unary data +-- constructor with name @n@ and argument @x@, in precedence context @d@. +{-# DEPRECATED showsUnary1 "Use showsUnaryWith to define liftShowsPrec" #-} +showsUnary1 :: (Show1 f, Show a) => String -> Int -> f a -> ShowS +showsUnary1 name d x = showParen (d > 10) $ + showString name . showChar ' ' . showsPrec1 11 x + +-- | @'showsBinary1' n d x y@ produces the string representation of a binary +-- data constructor with name @n@ and arguments @x@ and @y@, in precedence +-- context @d@. +{-# DEPRECATED showsBinary1 "Use showsBinaryWith to define liftShowsPrec" #-} +showsBinary1 :: (Show1 f, Show1 g, Show a) => + String -> Int -> f a -> g a -> ShowS +showsBinary1 name d x y = showParen (d > 10) $ + showString name . showChar ' ' . showsPrec1 11 x . + showChar ' ' . showsPrec1 11 y + +{- $example +These functions can be used to assemble 'Read' and 'Show' instances for +new algebraic types. For example, given the definition + +> data T f a = Zero a | One (f a) | Two a (f a) + +a standard 'Read1' instance may be defined as + +> instance (Read1 f) => Read1 (T f) where +> liftReadsPrec rp rl = readsData $ +> readsUnaryWith rp "Zero" Zero `mappend` +> readsUnaryWith (liftReadsPrec rp rl) "One" One `mappend` +> readsBinaryWith rp (liftReadsPrec rp rl) "Two" Two + +and the corresponding 'Show1' instance as + +> instance (Show1 f) => Show1 (T f) where +> liftShowsPrec sp _ d (Zero x) = +> showsUnaryWith sp "Zero" d x +> liftShowsPrec sp sl d (One x) = +> showsUnaryWith (liftShowsPrec sp sl) "One" d x +> liftShowsPrec sp sl d (Two x y) = +> showsBinaryWith sp (liftShowsPrec sp sl) "Two" d x y + +-} |