Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC Commits: b5d29ab8 by Brandon Chinn at 2026-08-25T18:42:08-04:00 Add Data.RealFloat and Infinity/NegInfinity/NaN pattern synonyms (#26961) - - - - - 6 changed files: - libraries/base/base.cabal.in - libraries/base/changelog.md - + libraries/base/src/Data/RealFloat.hs - testsuite/tests/interface-stability/base-exports.stdout - testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs - testsuite/tests/interface-stability/base-exports.stdout-mingw32 Changes: ===================================== libraries/base/base.cabal.in ===================================== @@ -117,6 +117,7 @@ Library , Data.Monoid , Data.Ord , Data.Proxy + , Data.RealFloat , Data.STRef , Data.STRef.Strict , Data.String ===================================== libraries/base/changelog.md ===================================== @@ -9,6 +9,8 @@ * Introduce `Data.Double` and `Data.Float` modules. ([CLC proposal #378](https://github.com/haskell/core-libraries-committee/issues/378)) * Change `Generically a`'s `Monoid` definition to require a `Semigroup` constraint, and define its `mconcat` using `(<>)` from that constraint. ([CLC proposal #413](https://github.com/haskell/core-libraries-committee/issues/413)) * Add `withEmptyCallStack` to `GHC.Stack`. ([CLC proposal #428](https://github.com/haskell/core-libraries-committee/issues/428)) + * Add new `Data.RealFloat` module re-exporting `RealFloat` from `GHC.Float` ([CLC proposal #394](https://github.com/haskell/core-libraries-committee/issues/394)) + * Add `Infinity`, `NegInfinity`, and `NaN` pattern synonyms to `Data.RealFloat` ([CLC proposal #394](https://github.com/haskell/core-libraries-committee/issues/394)) ## 4.23.0.0 *TBA* * Add `System.IO.hGetNewlineMode`. ([CLC proposal #370](https://github.com/haskell/core-libraries-committee/issues/370)) ===================================== libraries/base/src/Data/RealFloat.hs ===================================== @@ -0,0 +1,59 @@ +{-# LANGUAGE CPP #-} +{-# LANGUAGE PatternSynonyms #-} +{-# LANGUAGE Safe #-} +{-# LANGUAGE ViewPatterns #-} + +-- | +-- +-- Module : Data.RealFloat +-- Copyright : (c) The University of Glasgow 2026 +-- License : BSD-style (see the file libraries/base/LICENSE) +-- +-- Maintainer : libraries@haskell.org +-- Stability : stable +-- Portability : portable +-- + +module Data.RealFloat ( + RealFloat (..), + + -- * Infinity + NaN + pattern Infinity, + pattern NegInfinity, + pattern NaN, +) where + +import Data.Bool (Bool (..), (&&)) +import GHC.Internal.Data.Ord ((<), (>)) +import GHC.Internal.Float (RealFloat (..)) +import GHC.Internal.Real ((/)) +#if __GLASGOW_HASKELL__ >= 1001 +import qualified GHC.Essentials as Rebindable +#endif + +pattern Infinity :: (RealFloat a) => a +pattern Infinity <- ((\x -> isInfinite x && x > 0) -> True) where Infinity = 1/0 + +-- | Negative infinity +-- +-- Provided for convenience. Could also use the following instead: +-- * Pattern matching: @(negate -> Infinity)@ +-- * Expressions: @-Infinity@ +pattern NegInfinity :: (RealFloat a) => a +pattern NegInfinity <- ((\x -> isInfinite x && x < 0) -> True) where NegInfinity = -1/0 + +-- | A pattern synonym for NaN values. +-- +-- Note: Per IEEE 754, NaN is never equal to itself, thus these two snippets +-- have different behavior: +-- +-- @ +-- -- foo1 NaN == "a" +-- foo1 NaN = "a" +-- foo1 _ = "b" +-- +-- -- foo2 NaN == "b" +-- foo2 x = if x == NaN then "a" else "b" +-- @ +pattern NaN :: (RealFloat a) => a +pattern NaN <- (isNaN -> True) where NaN = 0/0 ===================================== testsuite/tests/interface-stability/base-exports.stdout ===================================== @@ -1626,6 +1626,29 @@ module Data.Ratio where denominator :: forall a. Ratio a -> a numerator :: forall a. Ratio a -> a +module Data.RealFloat where + -- Safety: Safe + pattern Infinity :: forall a. RealFloat a => a + pattern NaN :: forall a. RealFloat a => a + pattern NegInfinity :: forall a. RealFloat a => a + type RealFloat :: * -> Constraint + class (GHC.Internal.Real.RealFrac a, GHC.Internal.Float.Floating a) => RealFloat a where + floatRadix :: a -> GHC.Internal.Bignum.Integer.Integer + floatDigits :: a -> GHC.Internal.Types.Int + floatRange :: a -> (GHC.Internal.Types.Int, GHC.Internal.Types.Int) + decodeFloat :: a -> (GHC.Internal.Bignum.Integer.Integer, GHC.Internal.Types.Int) + encodeFloat :: GHC.Internal.Bignum.Integer.Integer -> GHC.Internal.Types.Int -> a + exponent :: a -> GHC.Internal.Types.Int + significand :: a -> a + scaleFloat :: GHC.Internal.Types.Int -> a -> a + isNaN :: a -> GHC.Internal.Types.Bool + isInfinite :: a -> GHC.Internal.Types.Bool + isDenormalized :: a -> GHC.Internal.Types.Bool + isNegativeZero :: a -> GHC.Internal.Types.Bool + isIEEE :: a -> GHC.Internal.Types.Bool + atan2 :: a -> a -> a + {-# MINIMAL floatRadix, floatDigits, floatRange, decodeFloat, encodeFloat, isNaN, isInfinite, isDenormalized, isNegativeZero, isIEEE #-} + module Data.STRef where -- Safety: Safe type role STRef nominal representational ===================================== testsuite/tests/interface-stability/base-exports.stdout-javascript-unknown-ghcjs ===================================== @@ -1626,6 +1626,29 @@ module Data.Ratio where denominator :: forall a. Ratio a -> a numerator :: forall a. Ratio a -> a +module Data.RealFloat where + -- Safety: Safe + pattern Infinity :: forall a. RealFloat a => a + pattern NaN :: forall a. RealFloat a => a + pattern NegInfinity :: forall a. RealFloat a => a + type RealFloat :: * -> Constraint + class (GHC.Internal.Real.RealFrac a, GHC.Internal.Float.Floating a) => RealFloat a where + floatRadix :: a -> GHC.Internal.Bignum.Integer.Integer + floatDigits :: a -> GHC.Internal.Types.Int + floatRange :: a -> (GHC.Internal.Types.Int, GHC.Internal.Types.Int) + decodeFloat :: a -> (GHC.Internal.Bignum.Integer.Integer, GHC.Internal.Types.Int) + encodeFloat :: GHC.Internal.Bignum.Integer.Integer -> GHC.Internal.Types.Int -> a + exponent :: a -> GHC.Internal.Types.Int + significand :: a -> a + scaleFloat :: GHC.Internal.Types.Int -> a -> a + isNaN :: a -> GHC.Internal.Types.Bool + isInfinite :: a -> GHC.Internal.Types.Bool + isDenormalized :: a -> GHC.Internal.Types.Bool + isNegativeZero :: a -> GHC.Internal.Types.Bool + isIEEE :: a -> GHC.Internal.Types.Bool + atan2 :: a -> a -> a + {-# MINIMAL floatRadix, floatDigits, floatRange, decodeFloat, encodeFloat, isNaN, isInfinite, isDenormalized, isNegativeZero, isIEEE #-} + module Data.STRef where -- Safety: Safe type role STRef nominal representational ===================================== testsuite/tests/interface-stability/base-exports.stdout-mingw32 ===================================== @@ -1626,6 +1626,29 @@ module Data.Ratio where denominator :: forall a. Ratio a -> a numerator :: forall a. Ratio a -> a +module Data.RealFloat where + -- Safety: Safe + pattern Infinity :: forall a. RealFloat a => a + pattern NaN :: forall a. RealFloat a => a + pattern NegInfinity :: forall a. RealFloat a => a + type RealFloat :: * -> Constraint + class (GHC.Internal.Real.RealFrac a, GHC.Internal.Float.Floating a) => RealFloat a where + floatRadix :: a -> GHC.Internal.Bignum.Integer.Integer + floatDigits :: a -> GHC.Internal.Types.Int + floatRange :: a -> (GHC.Internal.Types.Int, GHC.Internal.Types.Int) + decodeFloat :: a -> (GHC.Internal.Bignum.Integer.Integer, GHC.Internal.Types.Int) + encodeFloat :: GHC.Internal.Bignum.Integer.Integer -> GHC.Internal.Types.Int -> a + exponent :: a -> GHC.Internal.Types.Int + significand :: a -> a + scaleFloat :: GHC.Internal.Types.Int -> a -> a + isNaN :: a -> GHC.Internal.Types.Bool + isInfinite :: a -> GHC.Internal.Types.Bool + isDenormalized :: a -> GHC.Internal.Types.Bool + isNegativeZero :: a -> GHC.Internal.Types.Bool + isIEEE :: a -> GHC.Internal.Types.Bool + atan2 :: a -> a -> a + {-# MINIMAL floatRadix, floatDigits, floatRange, decodeFloat, encodeFloat, isNaN, isInfinite, isDenormalized, isNegativeZero, isIEEE #-} + module Data.STRef where -- Safety: Safe type role STRef nominal representational View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b5d29ab8ca1a520511394af84adf9739... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b5d29ab8ca1a520511394af84adf9739... 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