GHC 7.8.1

April 2014GHC 7.8.1Mailing list: GHC 7.8.1 releasedRelease notes for GHC 7.8.1

New language extensions:

• AllowAmbiguousTypes
• EmptyCase
• JavaScriptFFI
• NegativeLiterals
• NullaryTypeClasses
• NumDecimals
• OverloadedLists
• PatternSynonyms
• RoleAnnotations

Changes regarding the Typeable class:

• There is a new language extension,Automatically deriving Typeable instances in GHC 7.8 AutoDeriveTypeable, which instructs the compiler to automatically generate an instance of the Typeable class for every type. This extension flag will quickly become irrelevant in GHC 7.10 when auto-deriving becomes the default behavior.
• Hand-written Typeable instances are no longer permitted.
• Typeable can still be derived with the DeriveDataTypeable extension enabled.

Introduced the MINIMAL pragma.

GHCi now disables the monomorphism restriction by default.

Changes to generalized newtype deriving:

• It is now based on the new Coercible class.
• The notion of roles is introduced.Roles in GHC 7.8
• These changes will be described in Safe, zero-cost coercions for Haskell.

This GHC version corresponds to base version 4.7.0.0.base-4.7.0.0

• New: Data.Bool.bool :: a -> a -> Bool -> a, the catamorphism for Bool