ANNOUNCE: yap-0.0 - yet another prelude

Paterson, Ross R.Paterson at
Wed Aug 10 15:53:04 CEST 2011

Yet another restructuring of the Prelude numeric classes on algebraic lines, proposed for a revision of the Haskell Prelude:

It is less ambitious and more simplistic than other algebraic class hierarchies, but it aims to preserve backward compatibility for clients of the existing classes, and avoids multiple parameter type classes.  Of course defaulting is affected (this would be fixed if this proposal became part of the language) and definitions of instances will be different (but this is where the existing hierarchy is most problematic).  The core of the package is the new class hierarchy, but it also has some example instances, including for the existing types Complex and Ratio.  It is simplistic, but enough to allow fields like Ratio (Polynomial (Ratio (Complex Integer))).

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