Changes from Haskell 1.3 to Haskell 1.4

• List comprehensions have been generalized to arbitrary monads. (See Section 3.1.1 ).
• Import and export of class methods and constructors is no longer restricted to `all or nothing' as previously. Any subset of class methods or data constructors may be selected for import or export. Methods and constructors are now entities in their own right. (See Section 5.1.1).
• The defaulting rule now applies to type variables affected by the monomorphism restriction. (All implementations already do this - this officially sanctions the existing practice). (See Section 4.3.4).
• Qualified names may now be used as field names in patterns and updates.
• Ord is no longer a superclass of Enum. Some of the default methods for Enum have changed.
• Context restrictions on newtype declarations have been relaxed. (See section 4.2.3).
• The Prelude is now more explicit about some instances for Read and Show.
• The fixity of >>= has changed.
• The report is more explicit about context reduction problems. (See Section 4.5.3).
• Ratio and Rational have been added to the export list of the prelude.
• We're now using Unicode. See Lexical Structure.
• There's an extra warning about character IO (see Input/Output)

Haskell 1.4 is generally compatible with 1.3 - most of these changes are upward compatible. You may have problems with type signatures containing Enum if Ord instances are also used - you must add an explicit Ord context now that Enum does not imply Ord. The change in the fixity of >>= may also lead to incompatiblity. Instances which rely on the defaults in the class Enum may break.